Interventional endoscopy




Stricture dilation



Mouen Khashab
François Cessot
Sanjay Jagannath




  • Summary



  • Introduction 155


  • 1

    Clinical and endoscopic assessment 155


  • 2

    Equipment 157


  • 3

    Endoscopic techniques 157


  • 4

    Complications 161



Key Points





  • Apply the ‘rule of 3’ as a guideline when using bougie dilation to dilate esophageal strictures.



  • Do not perform pneumatic dilation in achalasia patients who are not fit for surgery because if perforation occurs, it may require surgical management. Alternative therapeutic options, such as Botox injection, may be better choices.



  • Esophageal dilation in the setting of eosinophilic esophagitis (EE) carries a high risk for deep tears and esophageal perforation. Dysphagia due to EE is best treated with topical steroids.



  • Use an upper endoscope for high-grade left-sided colonic strictures and a pediatric colonoscope for more proximal strictures.




Introduction


Strictures, both benign and malignant, occur in all regions of the gastrointestinal (GI) tract, but are most common in the esophagus. Dilation of benign strictures is considered definitive therapy, while dilation of malignant strictures is considered palliative therapy, primarily because the response to dilation is short-lived. Malignant strictures are dilated primarily to aid in the successful completion of other endoscopic procedures such as palliative stent placement or endoscopic ultrasonographic tumor staging.


An understanding of the various tools and techniques used to perform safe and effective GI stricture dilation is essential because: (1) strictures are commonly encountered in daily practice and (2) potential serious complications can occur when performing stricture dilation.



Clinical and endoscopic assessment



Esophageal strictures





  • Esophagogastroduodenoscopy (EGD) should be the initial diagnostic test in patients who (1) present with dysphagia consistent with an esophageal obstruction; (2) are at least 40 years of age with new onset dysphagia, and (3) in any patient with dysphagia and alarm symptoms (e.g. odynophagia, weight loss, anemia, etc).



  • Box 1 depicts the etiologies of mechanical esophageal obstruction.



    Box 1

    Causes of esophageal strictures





    • Peptic injury.



    • Schatzki’s ring.



    • Esophageal webs.



    • Esophageal cancer.



    • Corrosive injury.



    • Radiation therapy.



    • Esophageal surgery.



    • Eosinophilic esophagitis.



    • Sclerotherapy.



    • Photodynamic therapy (PDT).



    • Endoscopic mucosal resection (EMR).



    • Radiofrequency ablation (RFA).



    • Cryotherapy.



    • Sclerotherapy.



    • Infectious esophagitis.



    • Pill-induced esophagitis.





  • Anticoagulants should be discontinued for the procedure, based on existing recommendations (see Ch. 1 ).



  • The risk of bacteremia after esophageal bougienage is 12–22%, which is less than that associated with brushing of teeth. Antibiotic prophylaxis solely to prevent infectious endocarditis is not recommended prior to luminal stricture dilation.



  • Patients should fast for at least 4 h prior to the procedure, and ideally 8 h for patients who have eaten food. In certain clinical scenarios, such as achalasia dilation, patients should fast for longer time periods (see below).



  • Strictures are anatomically classified into simple or complex strictures. Complex strictures have at least one of the following features: asymmetry, diameter ≤12 mm, or inability to pass the endoscope. Complex strictures that are long or too tight to allow passage of an endoscope can be safely dilated under fluoroscopic guidance.



  • The esophageal mucosa should be examined for endoscopic features of eosinophilic esophagitis (EE). Esophageal dilation in the setting of EE carries a high risk for deep tears and esophageal perforation. Dysphagia in the setting of EE responds well to topical steroid therapy, and dilation may not be necessary.



  • For patients who complain of dysphagia, but do not have an endoscopically visible stricture, empiric esophageal dilation is discouraged. This technique has not been shown to be clinically effective. In addition, the patients may have undiagnosed EE, and dilation in this clinical scenario carries an extremely high risk of complication.



Clinical Tips





  • Patients with achalasia may need a prolonged fast prior to dilation because of a higher risk of aspiration due to esophageal stasis.



  • Look for endoscopic features of eosinophilic esophagitis: ringed esophagus and mucosal furrows. If EE is suspected, a total of five biopsy specimens must be obtained from the proximal and distal esophagus.



  • Do not perform empiric dilation for esophageal dysphagia when a stricture is not identified: it is clinically ineffective and has the potential risk of serious complications.



  • Biopsy specimens of the stricture should be obtained to exclude malignancy when the clinical presentation (such as rapid progression of dysphagia or significant weight loss) or the endoscopic appearance (such as the presence of a mass) is suggestive.



  • Biopsy specimens of a stricture to rule out occult malignancy should be obtained in patients with strictures that are refractory to dilation.





Gastric, pyloric, and small bowel strictures





  • Non-esophageal upper GI (UGI) strictures occur most commonly at the pylorus and manifest as gastric outlet obstruction. Etiologies of gastric or pyloric strictures are illustrated in Box 2 . Peptic ulcer disease (PUD) is the most common cause of gastric outlet obstruction.



    Box 2

    Causes of non-esophageal upper GI strictures





    • Peptic ulcer disease.



    • Corrosive injury.



    • Crohn’s disease.



    • Radiation therapy.



    • Postoperative.





  • Endoscopic dilation of UGI strictures due to Crohn’s disease often do not respond long term due to the high recurrence rate.



  • The use of fluoroscopy is advocated for strictures that cannot be traversed with the scope.



  • Roux-en-Y gastrojejunal bypass (RYGB) is one of the most common surgeries performed today for the treatment of morbid obesity. Gastrojejunal stomas are generally 10–12 mm in diameter. Anastomotic strictures are defined as stomas with diameter <10 mm and occur in 3–28% of these patients.



Clinical Tips





  • History of non-steroidal anti-inflammatory drugs (NSAIDs) intake needs to be elucidated in these patients and Helicobacter pylori infection needs to be ruled out.



  • Prolonged gastric outlet obstruction may result in gastric atony. Response to endoscopic therapy is not immediate in these patients.



  • Suspicious strictures must be biopsied to rule out malignancy.





Ileocolonic and colonic strictures





  • Etiologies of ileocolonic and colonic strictures are depicted in Box 3 . The most common site for these strictures is at surgical anastomoses.



    Box 3

    Causes of ileocolonic and colonic strictures





    • Postoperative.



    • Crohn’s disease.



    • Radiation injury.



    • NSAID colopathy.



    • Diverticular disease.



    • Ischemia.



    • Malignancy.





  • Dilation of colonic strictures should only be performed if the patient is symptomatic.



  • NSAID colopathy most commonly manifest in the right colon and may lead to colonic strictures with a pathgnomonic ‘diaphragm type’ appearance.




Equipment





  • Diagnostic upper endoscope



  • Pediatric colonoscope (for proximal colonic strictures)



  • Dilators ( Table 1 )



    Table 1

    Esophageal dilators





























    Mercury or tungsten-filled bougies Wire-guided polyvinyl bougies Balloon dilators
    Dilator type Maloney
    Hurst
    Savary
    American Endoscopy
    Celestin
    Through the scope (TTS)
    Controlled radial expansion (CRE) TTS
    Characteristics Maloney has tapered tip and Hurst has blunt tip Passed over a guidewire
    Available diameters 5–20 mm (15–60 French)
    May pass over a guidewire
    Available length 3–8 cm and diameter 6–20 mm (18–60 French)
    Advantages Blind self-home dilation performed by patients Widely available
    Inexpensive
    Relatively safe
    Widely available
    TTS
    Relatively safe
    Disadvantages Higher perforation rate with blind passage Endoscope needs to be removed before introducing the dilator Expensive



  • Guidewires



  • Fluoroscopy



  • Achalasia Rigiflex balloon dilator.




Endoscopic techniques



General principles



Dilation using bougies





  • Bougies exert both shearing and radial force and dilate progressively from the proximal to the distal end of the stricture ( Fig. 1 ).




    Figure 1


    Radial and longitudinal forces. Bougies are associated with longitudinal dilation forces (A), while balloon dilation is associated with radial dilation forces (B).



  • The initial dilator size chosen should equal the estimated diameter of the stricture.



  • Apply the ‘rule of 3’: Use no more than three dilators successively larger than the first dilator to meet moderate resistance when passed. This rule is a general guideline, and physicians should use their clinical discretion when dilating strictures.



  • Savary dilation involves passage of spring-tipped guidewire via the working channel of the endoscope, followed by withdrawal of the endoscope while leaving the guidewire in place ( Fig. 2 ).




    Figure 2


    Bougies.



  • If the stricture is not traversable by the endoscope, then the guidewire is passed through the stricture under fluoroscopic guidance, with the tip of the endoscope placed just above the stricture. The endoscope is then withdrawn leaving the guidewire in place. One should not advance the guidewire if firm resistance is met.



  • A conservative approach to dilation is recommended to reduce the risk of perforation. Patients are usually brought back in 1–2 weeks for repeat sessions to achieve sufficient dilation.



Clinical Tips





  • Do not try to accomplish too much dilating in one setting.



  • Apply the ‘rule of 3’ as a guideline when using bougie dilation. Use no more than three dilators successively larger than the first dilator to meet moderate resistance when passed.





Dilation using balloons





  • Balloons exert radial force only and the force is applied simultaneously to the entire length of the stricture ( Fig. 1 ).



  • The ‘rule of 3’ does not apply to balloon dilators.



  • There are multiple TTS balloons that are available in either single or multiple diameters. The balloons may be passed with or without wire guidance ( Fig. 3 ).




    Figure 3


    Ballon dilation. Balloons can also be placed on a guidewire outside the endoscope (A). Through the scope (TTS) esophageal balloonscan be non-wire guided (B) or wire guided (C).



  • The balloon is advanced through the working channel of an endoscope and then through the stricture under direct endoscopic visualization ( Figs 4, 5 ).




    Figure 4


    Balloon dilation. Syringe gun, manometer and balloon (A).Through the scope (TTS) balloon (B), and following inflation (C). TTS balloon is inserted into the operating channel (D).



    Figure 5


    Dilation of an esophageal stricture with a balloon. (A) Peptic stricture. (B) The balloon is placed across the stricture – note the ‘waist’ (arrow). (C) Note the obliteration of the waist following successful dilation. (D) Endoscopic image of the stricture during balloon dilation. (E) Following dilation: note the presence of several mucosal tears (white arrows).



  • The balloon should remain inflated for 30–60 s although the optimal duration is not known.



  • Fluoroscopic and wire guidance may be used for tight strictures that are not traversable with the endoscope.



  • Most widely used balloons are the controlled radial expansion (CRE) TTS balloons, which have three different inflation steps that achieve graded dilation.



Clinical Tips





  • It is of the utmost importance to maintain balloon position through the stricture during balloon inflation. The proximal portion of the catheter remaining outside of the endoscope should be held firmly against the endoscope using the endoscopist’s left little finger in order to prevent the balloon from slipping out of the stricture as it is inflated. Failure to do so may cause the balloon to slip out of the stricture and only part of the stricture may be dilated. In general, a slow inflation of the balloon to anchor to its initial diameter will secure it in the stricture and minimize the risk of migration. In addition, use of the longer balloon will help to minimize slipping out of the stricture.



  • You cannot apply the ‘rule of 3’ to balloon dilation.



  • Inflate the balloon using water and with radiologic product of contrast rather than air, because liquid is less compressible than gas in tight strictures.





Esophageal strictures





  • No difference in outcome has been observed between bougie and balloon dilation.



  • Schatzki’s rings are best treated with passage of single large diameter bougie (16–20 mm) to achieve rupture of the ring. Although most patients experience symptom relief after dilation, dysphagia recurs in 90% of patients within 3 years. Repeat dilation is advised on a needed basis. There is some evidence that acid suppression may prevent recurrence of Schatzki’s rings.



  • Webs occur in the upper and mid-esophagus and respond well to bougie dilation.



    Warning!


    Do not mistake eosinophilic esophagitis for multiple esophageal webs. These are different pathologies. Eosinophilic esophagitis carries a high risk of perforation, especially if dilation is performed with a single large diameter bougie.




  • Peptic strictures may be treated with bougienage (using the ‘rule of 3’) or balloon dilation. Patients should be placed on proton pump inhibitor (PPI) therapy and strictures will recur in as few as 30% of these patients.



  • Corrosive strictures require more dilation sessions and are associated with a higher recurrence rate as compared to peptic strictures. The use of bougies seems most suitable for these strictures.



  • Anastomotic strictures are common after esophagectomy, and are most commonly treated with balloon dilation.



  • Radiation-induced strictures are best treated with bougie dilation.



  • Injection of steroids into benign recurrent or refractory esophageal strictures may improve the outcome of dilation.



    Clinical Tips


    Steroid injection technique


    The procedure involves using 200 mg of triamcinolone (40 mg/mL). Using a standard sclerotherapy catheter, 1 mL aliquots are injected into the distal margin of the stricture in a four-quadrant fashion.




  • Dilation of malignant strictures provides only temporary relief of dysphagia that lasts from a few days to 2 weeks and it may be performed using either bougie or balloon dilation. Dilation is usually performed to allow passage of echoendoscope to perform tumor staging, stent placement, or laser therapy.



  • ASGE guidelines for the performance of esophageal dilation are summarized in Box 4 .



Box 4

ASGE guidelines for the performance of esophageal dilation





  • Fluoroscopy can be used when using non-wire guided dilators during dilation of complex esophageal strictures or in patients with a tortuous esophagus.



  • Bougie and balloon dilators are equally effective in patients with esophageal strictures.



  • The ‘rule of 3’ should be followed when dilation of esophageal strictures is performed with bougie dilators.



  • Steroid injection into recurrent or refractory benign esophageal strictures may improve the outcome after esophageal dilation.



  • Administration of PPIs is effective in preventing recurrence of esophageal strictures and the need for repeat esophageal dilation.




Clinical Tips





  • If you are not sure if the stricture is peptic or a Schatzki’s ring, treat it as a peptic stricture by using the ‘rule of 3’.



  • Remember that you only need to dilate the stricture to 13–15 mm diameter to relieve dysphagia.



  • PPI therapy improves outcome of peptic stricture dilation. This may also apply to Schatzki’s rings.





Achalasia





  • A thorough EGD examination is performed first to clear the esophagus of luminal contents, exclude esophageal or proximal gastric cancer (causing secondary achalasia), determine the extent of esophageal tortuosity, and identify the presence and localization of a hiatal hernia for appropriate localization of the LES fluoroscopically.



  • Pneumatic dilation is performed using Rigiflex balloon dilators with balloon diameters of 30 mm, 35 mm, or 40 mm.



  • Dilation is generally performed over a guidewire under fluoroscopic guidance initially using a 30 mm balloon. Non-fluoroscopically guided dilation using endoscopic visualization alone is feasible and can be performed safely in expert hands.



  • The balloon is first inflated to 3 pounds per square inch (PSI) to confirm appropriate localization of the balloon and looking for a waist in its center. The balloon is then inflated slowly up to a limit of 10 PSI. Complete obliteration of the waist should be noted fluoroscopically.



  • A water-soluble contrast esophagram should be obtained after the patient has awakened to rule out procedural perforation.



  • Fluoroscopy before and after dilatation should be performed to check for the presence of air in the mediastinum. If this is present it suggests that a perforation has occurred.



  • If the initial treatment is unsuccessful, repeat dilation with a larger balloon may be performed at a later setting.



  • Patients usually require 2–3 dilations over a 5-year period to remain in symptomatic remission.



  • Gastroesophageal reflux disease develops in some patients after pneumatic dilation, but it responds readily to PPI therapy.



  • ASGE guidelines for the performance of pneumatic dilation in achalasia are summarized in Box 5 .



Box 5

ASGE guidelines for the performance of pneumatic dilation in achalasia





  • Pneumatic dilation with large-diameter balloons is effective for the treatment of achalasia.



  • Botulinum toxin therapy is the preferred endoscopic treatment for achalasia in poor operative and non-operative patients.




Clinical Tips





  • Do not exceed a balloon pressure of 10 PSI because of an increased chance of perforation above this limit.



  • Do not perform pneumatic dilation in achalasia patients who are not fit for surgery because if perforation occurs, it may require surgical management. Alternative therapeutic options, such as Botox injection, may be better choices (see below).





Gastric/pyloric strictures





  • Pyloric strictures are mostly treated with balloon dilation although successful treatment using Savary dilators has also been reported in the literature.



  • A non-surgical approach for the treatment of these strictures is associated with high failure or recurrence rate. Repeat dilations every 1–2 weeks may be required to try to avoid surgery.



  • Long fibrous Crohn’s strictures are best treated surgically.



  • Pyloric strictures that are not traversable and those that are long and extend to the C loop of the duodenum are best dilated by passing the balloon over a guidewire under fluoroscopic guidance.



  • Gastrojejunal anastomotic strictures in RYGB patients can be treated effectively by using either balloon or bougie dilators. Dilation to 15 mm only is recommended to avoid weight regain.




Small intestinal/colonic strictures





  • Use an upper endoscope for high-grade left-sided strictures and a pediatric colonoscope for more proximal strictures. Enteroscopy (push or balloon) can be used to access and dilate strictures beyond the reach of an upper endoscope or colonoscope.



  • These strictures are usually treated using balloon dilators. Bougie dilation may be suitable for distal colonic or rectal strictures.



  • There is data to suggest that dilating colonic strictures to a diameter larger than 51 French is associated with better outcome. Large diameter balloons (up to 25 mm in size) are available for the treatment of colonic anastomotic strictures.



    Clinical Tip


    Most Crohn’s strictures occur at previous surgical anastomoses, although de novo stricture may occur and are also amenable to balloon dilation. However, only symptomatic strictures need to be treated!




  • Once the stricture is dilated allowing passage of the endoscope, the remaining proximal colon should be examined to evaluate for more proximal strictures. If there is any concern for malignancy, the stricture should be biopsied.



  • Colocolonic anastomotic strictures can be dilated to 15–18 mm in one treatment setting. In the setting of ileal or neo-terminal strictures, the initial dilation is taken to 10–12 mm. If there is no symptomatic response, a second dilation to 15 mm is undertaken during a later session. Strictures stemming from Crohn’s disease, diverticulitis, ischemia, or radiation therapy are rarely taken past 10–12 mm during the first treatment session.



Clinical Tip


If the colonic stricture cannot be traversed with an endoscope, fluoroscopy is used. Placement of the balloon over a guidewire is helpful for high-grade strictures and those associated with an end-to-side anastomosis. If difficulty is encountered in passing the guidewire across the stricture, a more flexible hydrophilic 0.021 or 0.035 mm ERCP guidewire may be helpful. In the case of near total colonic obstruction, a standard ERCP catheter may be placed over the guidewire and standard contrast will be used to determine the length and geometry of the stricture.




Complications





  • The most serious complication of esophageal dilation is perforation which occurs in 0.1–0.4% of procedures ( Box 6 ).



    Box 6

    Esophageal perforation





    • Occurs in 0.1–0.4% of patients undergoing dilation.



    • Risk is higher in complex strictures and radiation induced strictures.



    • Perforation should be suspected with symptoms and signs of fever, tachycardia, persistent pain, dyspnea or subcutaneous crepitus.



    • Confirm diagnosis with water-soluble contrast esophagram or contrast chest CT.



    • Many patients may be managed conservatively with nasogastric tube placement and intravenous antibiotics.



    • Some perforations are amenable to treatment with placement of an esophageal stent.





  • The published rate of perforation following dilation of malignant esophageal strictures is 10%. However, the actual rate in the hands of experienced endoscopists may be as low as 1–2%.



  • The risk of perforation with balloon dilation in achalasia is in the range of 3–4% with a mortality of <1%.



  • Perforation rate of 4–7% is reported in small series of balloon dilation of pyloric stenosis.



  • Most series describing colonic stricture dilation depicted a complication rate of about 5%.



Further Reading


  • Borotto E, Gaudric M, Danel B, et. al.: Risk factors of oesophageal perforation during pneumatic dilatation for achalasia. Gut 1996; 39: pp. 9-12.
  • Hernandez LV, Jacobson JW, Harris MS: Comparison among the perforation rates of Maloney, balloon, and savary dilation of esophageal strictures. Gastrointest Endosc 2000; 51: pp. 460-462.
  • Kochhar R, Makharia GK: Usefulness of intralesional triamcinolone in treatment of benign esophageal strictures. Gastrointest Endosc 2002; 56: pp. 829-834.
  • Kuwada SK, Alexander GL: Long-term outcome of endoscopic dilation of nonmalignant pyloric stenosis. Gastrointest Endosc 1995; 41: pp. 15-17.
  • Lemberg B, Vargo JJ: Balloon dilation of colonic strictures. Am J Gastroenterol 2007; 102: pp. 2123-2125.
  • Pereira-Lima JC, Ramires RP, Zamin I, et. al.: Endoscopic dilation of benign esophageal strictures: report on 1043 procedures. Am J Gastroenterol 1999; 94: pp. 1497-1501.
  • Sgouros SN, Bergele C, Mantides A: Eosinophilic esophagitis in adults: what is the clinical significance?. Endoscopy 2006; 38: pp. 515-520.



  • Emergency endoscopy in benign gastrointestinal obstruction



    Mouen Khashab
    Anne Le Sidaner
    Sanjay Jagannath




    • Summary



    • Introduction 162


    • 1

      Volvulus 162


    • 2

      Acute colonic pseudo-obstruction 165



    Key Points





    • Patients with acute gastric volvulus may present with Borchardt’s triad of pain, unproductive retching, and the inability to pass a nasogastric tube.



    • Acute endoscopic reduction of gastric volvulus can be performed using the alpha-loop maneuver.



    • An initial attempt at endoscopic detorsion can be followed in stable patients with sigmoid volvulus. Placement of a decompression tube decreases early recurrence.



    • Majority of patients with acute colonic pseudo-obstruction (ACPO) respond to neostigmine therapy. Placement of a decompression tube decreases recurrence.



    • Patients with ACPO who fail medical and endoscopic therapy should undergo surgical therapy.




    Information about the emergency management of gastroduodenal or colonic obstruction due to stricture or malignancy can be found in Chapter 7.3 .


    Introduction


    Gastroduodenal and colonic obstructions are common clinical entities treated by gastroenterologists and surgeons. It is critical to recognize those disease states that are better treated endoscopically and thus avoid the morbidity and mortality of a more invasive approach, e.g. surgery. Gastrointestinal obstruction may result from either mechanical cause or failure of intestinal motility in the absence of obstructing lesions (ileus, pseudo-obstruction). The obstruction should be classified as simple or strangulated, depending on whether there is absence or presence of intestinal ischemia, respectively. Strangulated obstructions have worse outcomes and treatment is generally surgical. Interventional gastroenterologists play a crucial role in the management of simple obstructions.



    Volvulus



    Gastric volvulus


    Gastric volvulus is a rare, potentially life-threatening entity that occurs when the stomach twists upon itself ( Fig. 1 ). By definition, gastric volvulus is rotation of the entire or part of the stomach more than 180°. It is supra-diaphragmatic and associated with a paraesophageal or a mixed diaphragmatic hernia in two-thirds of the cases, and is subdiaphragmatic in the remaining one third. The volvulus is organoaxial in 60% of cases where the axis passes through the gastroesophageal and gastropyloric junctions, and mesenteroaxial in 40% of cases where the axis bisects the lesser and greater curvatures.




    Figure 1


    Barium contrast study showing organoaxial gastric volvulus (arrow).


    Gastric volvulus can present as: (1) transient event with mild short-lived upper abdominal symptoms; (2) chronic volvulus with mild and non-specific symptoms such as dysphagia, hiccups, early satiety, bloating, heartburn, and upper abdominal discomfort, with symptoms being worse after meals; or (3) acute gastric volvulus which presents with sudden onset of severe pain in the upper abdomen or lower chest and unproductive retching. Some patients present with Borchardt’s triad of pain, unproductive retching, and the inability to pass a nasogastric tube.


    Although strangulation is more common in organoaxial volvulus, it only occurs in 5–28% of these cases due to the rich blood supply of the stomach. Mesenteroaxial volvulus usually causes incomplete obstruction that may be intermittent in nature.


    If gastric volvulus is associated with a diaphragmatic hernia, physical examination may reveal evidence of the stomach in the left chest. Chest X-ray will reveal a gas-filled viscus in the chest. The diagnosis is usually confirmed with a barium upper gastrointestinal study. Upper endoscopy will show twisting of gastric folds at the point of torsion.



    Warning!





    • EGD should be avoided if there is suspicion of gastric ischemia or perforation, such as in patients with rebound abdominal tenderness.



    • If EGD is performed, the endoscope should be advanced forward gently and air insufflation should be kept to a minimum.




    Acute gastric volvulus carries a high mortality risk if not recognized early. Early diagnosis and surgical correction remain the mainstays of therapy. Nonetheless, gastroenterologists still play a crucial role in the diagnosis and management of acute and chronic gastric volvulus.




    • Chronic gastric volvulus presents with mild and non-specific symptoms. The endoscopist performing the EGD can recognize the presence of twisted gastric folds, which establishes the diagnosis.



    • An endoscopist may diagnose acute gastric volvulus when performing upper endoscopy on a patient with more severe and acute symptoms. Stomach decompression with a nasogastric tube may be attempted. Reduction of an acute volvulus may be achieved with this intervention alone.



      Clinical Tip


      Placement of a nasogastric tube in acute gastric volvulus may be unsuccessful in patients with organoaxial rotation due to complete obstruction at the cardia.




    • The gastric mucosa should be inspected carefully for signs of ischemia and necrosis. The examination should be aborted if these signs are present because such patients are at higher risk of perforation with air insufflation.



    • If signs of gastric infarction are not present, acute endoscopic reduction of the volvulus may be considered using the alpha-loop maneuver, which should be performed under fluoroscopic guidance.



      Clinical Tips


      The alpha-loop maneuver ( Fig. 2 )





      • The endoscope is slowly advanced through the narrow lumen formed by the twisted gastric folds of the fundus or body into the antrum. Once the antrum is entered, a J-turn maneuver is performed to confirm the passage of the endoscope through the gastric volvulus.



      • The endoscope is then withdrawn back into the fundus. The endoscope is retroflexed and advanced with gentle pressure in the proximal stomach to form an alpha-loop. The tip of the endoscope is passed anterior to the retroflexed portion and re-advanced through the narrowed lumen into the antrum.



      • The endoscope is then torqued in a clockwise manner to allow untwisting of the alpha-loop and reduction of the gastric volvulus.




      Figure 2


      Alpha-loop maneuver. (A) An Olympus magnetic imager showing an alpha loop and (B,C) the reduction of the volvulus, with straightening of the colonoscope.




    • In surgically fit patients, semi-elective laparoscopic gastropexy should follow the reduction of gastric torsion after the patient is stabilized. Associated diaphragmatic hernias should also be repaired.



    • In surgically unfit patients, simple endoscopic gastropexy may be performed by placement of one or two percutaneous gastrostomy (PEG) tubes.



    • A management algorithm for patients with gastric volvulus is illustrated in Figure 3 .




      Figure 3


      Management algorithm for patients with acute gastric volvulus.




    Colonic volvulus


    Colonic volvulus is the third most frequent cause of large bowel obstruction after neoplasms and diverticulitis. Whereas colonic neoplasms and diverticulitis usually result in an open-loop obstruction where the lumen is occluded at a single point along the bowel segment, colonic volvulus occurs when a colonic segment becomes twisted on its mesenteric axis and occludes both ends of the bowel segment resulting in a closed-loop obstruction ( Fig. 4 ). The mesentery gets trapped and the blood supply to the bowel segment becomes strangulated, potentially leading to gut ischemia, necrosis and perforation. Delay in diagnosis and decompression compromises viability of the bowel and is a major cause of mortality.




    Figure 4


    (A) Plain AXR showing grossly distended loop of sigmoid colon. (B) Contrast radiology shows typical ‘bird’s beak’ occlusion at site of volvulus (arrow).


    The sigmoid colon ( Fig. 4 ) and cecum ( Fig. 5 ) are the most frequent sites of colonic volvulus, accounting for 75% and 22% of all cases, respectively. Patients with acute colonic volvulus present most commonly with acute abdominal distension and may have other non-specific symptoms of abdominal pain, nausea, vomiting, and constipation. The diagnosis of colonic volvulus can be made with plain abdominal films (supine and upright) or water-soluble contrast enemas in 85% of the cases.



    Clinical Tips





    • The use of barium as the contrast medium during contrast enema studies in patients with suspected colonic volvulus is discouraged because of risk of severe peritonitis in case of bowel perforation.



    • A contrast-enema study may occasionally cause volvulus detorsion.





    Figure 5


    Cecal volvulus. (A) Contrast enema study showing a cecal volvulus. (B) Reduction of the cecal volvulus with rectal tube inserted.


    Acute colonic volvulus should be managed on an emergent basis. Patients with colonic necrosis/perforation should be managed surgically. A more conservative approach with an initial attempt at endoscopic detorsion and decompression can be followed in more stable patients ( Fig. 6 ). The benefits of such a strategy are:




    • Avoid emergency surgery on an un-prepped colon with risk of field contamination



    • Avoid colostomy and its associated morbidity and mortality



    • Improve quality of life by avoiding colostomy



    • Allow a one stage semi-elective surgery with the possibility of a laparoscopic approach



    • Assess the viability of colonic mucosa.



    Clinical Tips


    Endoscopic treatment of colonic volvulus





    • Consult with your surgical colleagues before any attempt at endoscopic management of colonic volvulus.



    • Avoid excessive air insufflation to minimize risk of perforation.



    • Consider using carbon dioxide, if available, for colonic insufflation.



    • Examination should be aborted if there is any evidence of colonic gangrene (e.g. the presence of bloody effluent in the colonic lumen is an indication of bowel gangrene); detorsion should be avoided in these cases as it can precipitate an irreversible septic shock.



    • The volvulus should be traversed slowly with a flexible endoscope in the usual manner. A gush of stool is expected after successful detorsion.



    • Place a decompression tube over a guidewire to decompress the distended colon and to decrease the early recurrence risk. Early recurrence rate is unacceptably high without tube placement. The tube should be placed on low intermittent suction and should be flushed with 20–30 mL of water or normal saline solution every 6 hours to maintain patency.



    • Perform supine and upright abdominal radiography to confirm successful detorsion and to exclude pneumoperitoneum.



    • Endoscopic treatment of colonic volvulus is only a temporizing measure.




    Warning!


    Endoscopic management of cecal volvulus is less well defined than sigmoid volvulus because of a lower success rate (<33%) and a heightened cecal perforation rate because of the thinned-wall cecum.




    Figure 6


    Endoscopic view of a sigmoid volvulus. (A) Before reduction. (B) Following endoscopic reduction.


    Colonic segmental resection and primary anastomosis is considered the treatment modality of choice of colonic volvulus after successful endoscopic detorsion. Non-resectional techniques such as colonopexy and colonostomy carry a substantial risk of recurrence, but may be considered in high-risk patients.



    Acute colonic pseudo-obstruction


    Acute colonic pseudo-obstruction, also known as Ogilvie’s syndrome, is a disorder characterized by massive colonic dilation in the absence of colon obstruction. This definition excludes toxic colitis, which occurs in the setting of severe colitis secondary to inflammatory bowel disease or infection. It occurs most often in the setting of surgery and severe medical illnesses, and thus is a disorder of institutionalized patients. Acute colonic pseudo-obstruction is believed to result from autonomic imbalance with suppressed large bowel parasympathetic tone. This results in decreased colonic motility, accumulation of gas and fluid in the colon, increased intraluminal pressure, colonic distension and rising wall tension. Wall tension is highest in the cecum where the colonic diameter is the largest. This may result in the impediment of cecal capillary circulation and lead to ischemia, gangrene, and subsequent perforation. Plain abdominal radiographs show diffuse dilatation of the colon. A cutoff in the colonic gas is often seen at the hepatic flexure, splenic flexure, or sigmoid region with minimal air distal to the cutoff (collapsed left colon). Unlike toxic colitis, preserved haustral markings, smooth inner colonic contour, and thin colonic wall are present. In contrast to mechanical obstruction, air fluid levels are absent and distension is gaseous ( Figs 7, 8 ). Water-soluble contrast enema is usually needed to rule out a true mechanical obstruction.



    Clinical Tips





    • Radiographic contrast enemas are frequently needed in patients with acute colonic pseudo-obstruction to rule out mechanical obstruction.



    • Avoid using barium as the contrast medium because of peritonitis risk if perforation occurs.



    • The use of water-soluble contrast enema has a therapeutic effect in some patients by stimulating colonic motility, which sometimes speeds recovery.



    • There is a small risk of colonic perforation with the use of enemas in patients with acute colonic pseudo-obstruction.



    • Computed tomography scan may be needed in some patients to rule out a true mechanical obstruction.



    • Clostridium difficile infection should be excluded with appropriate stool testing.





    Figure 7


    Acute colonic pseudo-obstruction. (A) A large dilated loop of bowel (white arrows). (B) A colonic decompression tube (white arrow) has been inserted as far as the splenic flexure.



    Figure 8


    Acute colonic pseudo-obstruction. (A) A plain abdominal film with evidence of large bowel dilation due to pseudo-obstruction. (B) A rectal decompression tube. (C) Insertion of the tube parallel to the colonoscope.


    Therapy of acute colonic pseudo-obstruction can be divided into conservative treatment and active interventions. Conservative measures should be tried for 24–48 h, after which the condition usually resolves in most patients (at least in 75% of cases). Active interventions should be implemented if the disease progresses or does not respond to conservative measures.



    Box 1

    Treatment of acute colonic pseudo-obstruction: conservative measures





    • Patients should be kept nothing by mouth.



    • Nasogastric decompression should be initiated.



    • Test for and correct any electrolyte imbalance (in particular potassium, magnesium, calcium, and phosphorus).



    • Test for and treat thyroid dysfunction.



    • Discontinue or minimize offending drugs, such as narcotics and anticholinergics, if possible.



    • Mobilize patients out of bed if feasible.



    • Manage concurrent illnesses.



    • Obtain abdominal radiographs once every 12–24 h to follow cecal diameter.



    • Serial abdominal examinations should be performed to assess for tenderness, worsening abdominal distension and signs of peritonitis.



    • Water-soluble contrast enemas may be tried to liquefy the stool and stimulate colon motility.




    Warning!





    • Conservative treatment alone should only be implemented when pain and abdominal distension are not extreme, and cecal diameter is <12 cm.



    • Conservative treatment alone should be tried for a maximum of 48 hours in patients with tolerable symptoms because perforation risk increases significantly after 4–5 days.




    Active interventions, including treatment with neostigmine and/or colonoscopic decompression, should be considered in patients who do not respond to a maximum of 48 h of conservative therapy, those with extreme abdominal pain, and those with cecal diameter >12 cm.


    Neostigmine, an anticholinesterase parasympathomimetic agent, is usually the first medical agent tried in patients who do not have any contraindications to its use.



    Box 2

    Facts about neostigmine





    • Three placebo-controlled double-bind randomized trials have documented the effectiveness of neostigmine.



    • The majority of patients (80–90%) will respond to neostigmine with prompt evacuation of flatus and/or stool and a reduction in abdominal distension.



    • It is given as a 2 mg intravenous dose. The dose may be repeated every 3 (or more) hours in case of recurrence.



    • It has a low side-effect profile but potential serious side-effects, such as bronchospasm, bradycardia, hypotension, and seizures may occur. Side-effects are usually short lasting because of the short half-life of neostigmine.



    • Neostigmine should only be given under close cardiac monitoring (continuous EKG monitoring and intermittent blood pressure measurements for 30 min after the dose is given). Atropine should be immediately available and should be given only for severe, prolonged, or symptomatic bradycardia.



    • Other side-effects include salivation, nausea, vomiting, abdominal pain, restlessness, tremor, miosis, and sweating.



    • The elimination half-life is prolonged in patients with renal insufficiency.



    • Absolute contraindications to the use of neostigmine include the following: known hypersensitivity and mechanical urinary or intestinal obstruction. Relative contraindications include recent myocardial infarction, acidosis, asthma, bradycardia, peptic ulcer disease, and therapy with beta-blockers.




    Colonoscopic decompression with placement of decompression tube should be performed in patients who fail neostigmine treatment.



    Box 3

    Facts about colonoscopic decompression in patients with acute colonic pseudo-obstruction





    • Colonoscopic examination aids in ruling out mechanical obstruction and signs of colonic ischemia or necrosis.



    • Decompression colonoscopy reduces colonic distension and prevents ischemia and perforation.



    • Air insufflation should be kept to a minimum and the use of carbon dioxide, if available, for insufflation is advisable.



    • Initial colonoscopic decompression is successful in about 70% of patients. In up to 40% of cases, the distension recurs requiring repeat colonoscopy.



    • After repeat colonoscopy, the overall clinical success rate increases to 73–85%.



    • Placement of a decompression tube in the right colon (proximal to the splenic flexure) increases the success rate to >90%.



    • Decompression colonoscopy, although technically demanding, can be preformed safely with a reported mortality rate of 1% and a morbidity rate of 3% (mainly perforation risk).



    • It is debatable if colonoscopy should be aborted if signs of colonic ischemia are present.



    • Placement of a decompression tube has been shown to decrease recurrence rate.



    • Colon preps/enemas are not needed because the stool remaining in the colon is usually liquefied and the colonic lumen is distended.



    • Each colonic segment should be decompressed as soon as it is entered with the colonoscope.



    • Cecal intubation is desired (if possible) for cecal examination and complete decompression.



    • A guidewire is placed through the working channel of the colonoscope and advanced to the cecum (or the most proximal point reached by the colonoscope). The endoscope is then withdrawn and the decompression tube is placed over the wire.



    • Fluoroscopy is needed for optimal tube placement to avoid the common problems of coiling of the tube and distal guidewire migration (which usually results in distal placement of the tube in the left colon).



    • The tube should be taped securely to the buttocks, placed on low intermittent suction, and flushed with water or saline every 6 hours to prevent clogging.



    • Daily abdominal radiographs should be obtained to follow colonic diameter and exclude pneumoperitoneum.




    Patients who fail medical and endoscopic treatment and those with signs of colonic perforation/necrosis should be treated surgically with cecostomy or colectomy. Figure 9 illustrates an algorithm suggested by the ASGE for treating patients with ACPO.




    Figure 9


    ASGE algorithm for managing patients with ACPO.


    Further Reading


  • Eisen GM, Baron TH, Dominitz JA, et. al.: Acute colonic pseudo-obstruction. Gastrointest Endosc 2002; 56: pp. 789-792.
  • Godshall D, Mossallam U, Rosenbaum R: Gastric volvulus: case report and review of the literature. J Emerg Med 1999; 17: pp. 837-840.
  • Loftus CG, Harewood GC, Baron TH: Assessment of predictors of response to neostigmine for acute colonic pseudo-obstruction. Am J Gastroenterol 2002; 97: pp. 3118-3122.
  • Madiba TE, Thomson SR: The management of cecal volvulus. Dis Colon Rectum 2002; 45: pp. 264-267.
  • Ponec RJ, Saunders MD, Kimmey MB: Neostigmine for the treatment of acute colonic pseudo-obstruction. N Engl J Med 1999; 341: pp. 137-141.
  • Renzulli P, Maurer CA, Netzer P, Buchler MW: Preoperative colonoscopic derotation is beneficial in acute colonic volvulus. Dig Surg 2002; 19: pp. 223-229.
  • Tejler G, Jiborn H: Volvulus of the cecum. Report of 26 cases and review of the literature. Dis Colon Rectum 1988; 31: pp. 445-449.
  • Tsang TK, Walker R, Yu DJ: Endoscopic reduction of gastric volvulus: the alpha-loop maneuver. Gastrointest Endosc 1995; 42: pp. 244-248.



  • Esophageal, duodenal and colorectal stenting



    Mouen Khashab
    Jean-Christophe Létard
    Jean Marc Canard
    Sanjay Jagannath




    • Summary



    • Introduction 168


    • 1

      General principles 168


    • 2

      Esophageal stenting 169


    • 3

      Duodenal stenting 173


    • 4

      Colonic stenting 175



    Key Points





    • Covered self-expandable metal stents (SEMS) resist tumor ingrowth, may be removable, and have a higher incidence of migration. Uncovered SEMS are non-removable, migrate less often, but tumor ingrowth occurs frequently.



    • The various esophageal SEMS are equivalent in technical success, efficacy, and complication rates when used for malignant strictures.



    • Patients with malignant gastric outlet obstruction and short life expectancy are best treated with endoscopic stenting.



    • Main indications for colonic stenting are bridge to surgery in patients with colorectal cancer who present with colonic obstruction and palliation of inoperable malignant colorectal obstruction.




    Introduction


    Advances in interventional endoscopy over the last two decades have made an immense impact on clinical care. One such advance is the endoscopic placement of stents for the treatment and palliation of benign and malignant strictures involving the esophagus, duodenum, and colorectal regions of the gastrointestinal tract.


    Esophageal cancer is one of the most lethal malignancies in the Western world. The incidence of esophageal cancer is rising at a faster rate as compared to any other GI cancer, and fewer than 50% of cases are curable and the 5-year survival rate is only 5–10%. For these reasons, palliative treatment of esophageal cancer remains an essential part of its management. Palliative esophageal surgery is associated with unacceptably high morbidity and mortality; it has largely been replaced by chemoradiation, brachytherapy, and/or endoscopic therapy. Among the available endoscopic techniques, endoluminal stenting is the most commonly employed because of its efficacy and wide availability.


    Tumors involving the gastric outlet or the duodenum cause symptoms and signs of gastric outlet obstruction. Neoplasms that most commonly result in gastric outlet obstruction include pancreatic cancer, gastric cancer, carcinoid tumor, and metastases from other primary malignancies. Multiple studies have shown that palliative stent placement for unresectable tumors, as compared with palliative surgery, is more efficacious, cost-effective, and is associated with less morbidity and mortality.


    Colorectal cancer, the third leading cause of new cancer diagnoses in the USA, often presents with partial or complete colon obstruction. Colorectal stenting has been used effectively for both palliation of malignant obstruction and as a bridge to curative surgery.


    This aim of this chapter is to describe the general principles of GI luminal stenting and to focus on the use of endoscopically placed stents to treat benign and malignant obstruction of the esophagus, duodenum, and colon.



    General principles





    • Two broad categories of stents exist currently: self-expandable metal stents (SEMS), and self-expandable plastic stents (SEPS). In the past, semi-rigid plastic stents were used, but were associated with a higher complication rate, longer hospital stay, and worse clinical outcome when compared to SEMS and SEPS. Semi-rigid plastic stents are no longer used.



    • Several manufacturers retail SEMS designed specifically for esophageal, duodenal, biliary, or colonic placement. These products differ in their physical properties and characteristics (length, diameter, flared endings, shortening during expansion, rigidity, material, radial expansive force, removability, and delivery systems).



    • Covered and uncovered SEMS are available. Covered SEMS are designed to resist tumor ingrowth, while uncovered SEMS embed into the stricture and surrounding tissue. Fully covered SEMS ( Fig. 1 ) may be removable, but have a higher incidence of migration. Uncovered SEMS are non-removable, migrate less often, but tumor ingrowth occurs frequently.




      Figure 1


      Fully covered SEMS. (A) Patient with multiple esophageal strictures, which were resistant to repeat dilation. (B) Fully covered esophageal stent inserted across the stricture. (C) Fluoroscopic image.



    • Covered stents offer better long-term palliation for malignant disease than uncovered stents.



    • One self-expandable plastic stent (Polyflex, Boston Scientific, Natick, MA) is available for esophageal use. This stent does not embed into the tissue and is approved by the US Food and Drug Administration (FDA) for benign disease and removability.



    • All self-expandable stents may be placed with high rates of technical success with fluoroscopic guidance.




    Esophageal stenting



    General concepts





    • Of patients with esophageal cancer, 50–60% present with surgically unresectable disease



    • Dysphagia is the most distressing symptom



    • Dilation only transiently improves dysphagia and carries a significant risk of perforation



    • Dilation is primarily used as an adjunct treatment for stenting



    • Stenting provides rapid relief of dysphagia



    • All esophageal SEMS are covered



    • The three most commonly studied SEMS are: Ultraflex, Wallstent, and Z-stent. Other stents exist



    • The Polyflex stent is FDA-approved for the palliation of malignant diseases and for the treatment of benign diseases of the esophagus



    • Currently available esophageal stents are not placed through the scope.




    FDA-approved expandable esophageal stents ( Table 1 )



    Ultraflex stent





    • Ultraflex stent is partially coated (with a polyurethane membrane lining the middle of the stent while the proximal and distal 1.5 cm is uncovered).



    • It has an easy-to-use delivery system which is 5.3 mm in diameter and can be deployed from the proximal to the distal end or vice-versa.



    • The flared proximal end reduces the risk of food pocket formation between the stent and the wall and anchors the stent to the esophageal wall.



    • The stent can theoretically be repositioned, if necessary, by means of a wire at its upper end.



    • It is slow to expand (encouraging the patient to start eating again cautiously and gradually).



    • Expansion is occasionally incomplete, requiring balloon dilation, which is not always effective. Perforation is rare.



    • The Ultraflex stent has no bare metal edges and is less traumatic to the mucosa compared to the Wallstent.



    Clinical Tips


    Among all SEMS, the Ultraflex stent produces the least radial expansive force which, in theory, may be clinically relevant:




    • Decreased risk of fistula formation



    • Decreased risk of perforation



    • Diminished efficacy (less relief from dysphagia).




    Table 1

    FDA-approved expandable esophageal stents



































































    Stent type Manufacturer Material Covering Deployment diameter (mm) Release system Degree of shortening Features
    Ultraflex Boston Scientific Nitinol Partial or uncovered 18, 22 Proximal or distal 30–40% Proximal flared end, no bare metal ends
    Wallstent II Boston Scientific Cobalt-based alloy Partial 20 Distal 20–30% Flared ends, bare metal ends, reconstrainable
    Z-stent Cook Endoscopy Stainless steel Full or partial 18 Distal None Flared ends
    Z-stent with Dua Antireflux Valve Cook Endoscopy Stainless steel Full 18 Distal None Windsock on distal end to prevent gastroesophageal reflux when placed across gastroesophageal junction
    Alimaxx-E Alveolus Nitinol Full (internally lined) 18, 22 Distal None Internally lined
    Polyflex Boston Scientific Polyester/silicone Full 16, 18, 21 Distal 30–40% Proximal flared end, approved for removability



    Wallstent II





    • This stent is partially coated with bare proximal and distal ends (2 cm on each end).



    • It is easy to place and can be repositioned during the procedure. The stent can be recaptured as long as <50% of the stent has been deployed.



    • The stent may foreshorten after deployment.



    • The stent exerts a high radial force which may translate into better dysphagia relief, but increased post-procedural pain.



    • It appears ideal for patients with advanced lesions.




    Z-stent





    • This stent is available as fully coated or partially coated with exposed flanges.



    • The delivery system is rigid, and stent assembly is more complicated than other commercially available SEMS.



    • A Z-stent with a ‘Dua’ antireflux valve is available for lesions that extend across the gastroesophageal junction (GEJ). The antireflux valve is an 8 cm extension of the polyurethane coating beyond the distal stent border. This polyurethane ‘windsock’ creates a one-way valve that shuts, with a rise in intragastric pressure, by collapsing on itself. With further increase in intragastric pressure, the valve can invert to allow vomiting or belching and returns, following a sip of water, to the intragastric position.




    Alimaxx-E stent





    • This is a relatively new stent and data are limited.



    • The delivery system (7.4 mm in diameter) is easy to use.



    • It is the only SEMS that is completely covered with a biocompatible membrane.



    • The Alimaxx-E stent is the only SEMS in which removability is included in the guidelines for use (not FDA-approved yet).



    • To remove the stent, grasp with suture, which is located at the proximal end of the stent, with a rat-tooth forceps. Then, apply firm, continuous traction by pulling on the endoscope in order to ‘peel’ the stent off the esophageal wall, and thus facilitate relatively atraumatic repositioning or removal.




    Polyflex stent





    • This is the only available SEPS ( Fig. 2 ).




      Figure 2


      Polyflex. This is the same patient as in Figure 1 , with multiple esophageal strictures (A). The strictures were dilated (B) and a Polyflex stent inserted (C). However, this migrated into the stomach (D) necessitating removal and insertion of an fully covered removable SEMS.



    • The delivery system (diameter of 13 mm) is cumbersome. As such, Polyflex deployment frequently requires predeployment stricture dilation to 12–14 mm.



    • It is the only stent approved for treatment of benign diseases of the esophagus and for removability (up to 9 months after placement).




    Technique of stent placement





    • The Ultraflex, Alimaxx-E, and Polyflex stents may be placed endoscopically without fluoroscopic guidance; however, fluoroscopic guidance is commonly used.



      Clinical Tips





      • If a stricture is not traversable with a standard endoscope, a pediatric endoscope (6 mm diameter) may be used, if available.



      • If the stricture is not traversable with the endoscope, stent placement must be performed under fluoroscopic guidance.



      • The stricture needs to be dilated to allow passage of the delivery system (usually to a diameter of 9–10 mm and not exceeding 12–14 mm).



      • If an endoscope cannot be passed beyond the stricture, the length and geometry of the stricture can be defined using a balloon and water insoluble contrast.





    • The proximal and distal borders of the tumor are marked by endoscopic clips, injection of contrast material using sclerotherapy needle, or placement of external radio-opaque markers ( Fig. 3 ).



      Clinical Tip


      It is best to have the patient in supine position when external markers are placed, for optimal fluoroscopic visualization. Keep patient in same position during stent deployment.






      Figure 3


      Insertion of esophageal stent. (A) Placement of radio-opaque marker and guide wire. (B) Measure distance of proximal and distal tumor margins from the teeth. (C) Delivery system through the stenosis. (D) Distal stent deployment. (E) The system is withdrawn. (F) Stent deployed.



    • A stiff guidewire is positioned in the stomach through the stenosis.



    • The scope is withdrawn.



    • The delivery system with the stent is passed to the stomach over a stiff guidewire. The system is then withdrawn and the stent deployed with the assistance of fluoroscopy, so that the markings on the stent indicate that placement will be with at least a 2 cm margin proximal and distal to the marked tumor margins.



    • Repeat endoscopic examination may be done to confirm the proximal end of the stent is above the proximal tumor margin.



      Clinical Tips





      • Avoid traversing the stent after deploying it because of migration risk, as the stent has not fully expanded. Full stent expansion takes about 48 h.



      • It is crucial to choose the proper stent length that will bridge the entire tumor. This may be accomplished by measuring the tumor length endoscopically or fluoroscopically.



      • Remember that the chosen stent should be 2–4 cm longer than the stricture to allow for a 1–2 cm margin above and below the stricture proximal and distal margins. This allows for the covered portion of the stent to cover the stricture, thus reducing tumor ingrowth.





    • More than one stent may be needed to cover long strictures. The second stent is placed in the same manner and positioned such that the two stents overlap for a distance of about 1–2 cm.



      Clinical Tip


      Do not leave an excessive length of stent in the stomach because of the risk of gastric ulceration and bleeding when the stent rubs against the opposite gastric wall.




    • If deployment is suboptimal based on fluoroscopic appearance, the stent may be dilated using a TTS balloon.



    • Prescribe pain medications and proton pump inhibitor therapy before patient is discharged. Patients should also be advised on specific nutritional guidelines ( Box 1 ).



    Box 1

    Nutritional guidelines following esophageal stent placement





    • Have liquids for the first 24 h as the stent has not fully expanded.



    • Chew all food properly and avoid dense and fibrous foods.



    • Eat 5–6 small meals per day if needed.



    • Eat slowly and take small bites.



    • Sit upright while eating.



    • Drink fluids in between meals if one feels ‘full’ with meals.



    • Remain in an upright position at least 30–60 min after eating.



    • If food ever feels ‘stuck’ in your throat, take sips of Coca-Cola. One may repeat this throughout the day, especially before and after meals.





    Stent retrieval techniques





    • The most commonly used method for retrieving stents is to grasp the proximal end of the stent with forceps or endoscopic snares, and then to pull out the endoscope, stent, and forceps/snare as one unit. Injury to the gastric or esophageal mucosa may occur and an overtube or a retrieval hood can be used to minimize this.



    • The stent may be removed using a regular upper endoscope. Some endoscopists prefer using the double-channel therapeutic endoscope with two rat-tooth forceps or a rat-tooth forceps and a snare for stent removal.




    Outcome data (efficacy)





    • Technical success rates for placement of esophageal SEMS is close to 100%. Placement of SEPS (Polyflex) is more cumbersome and the technical success rate is reportedly lower than that of SEMS (approximately 85%).



    • Rapid and prolonged improvement of dysphagia occurs in the majority of patients.



    • Polyflex has higher migration rates compared to SEMS, especially when placed across the GE junction.



    • Migration rates are higher with benign disease (30–70%) and efficacy is significantly lower. Some studies report long-term improvement in as few as 6% of patients.



    • Although the Alimaxx-E stent is not FDA-approved for removability, it is the only SEMS that has an indication for removability. It is currently being widely used to treat both malignant and benign diseases of the esophagus. The stent appears easier to remove if it has been in place for a shorter period of time (e.g. 4–6 weeks).



    Box 2

    Take home points





    • Newer stents (SEMS and SEPS) are superior to the obsolete semi-rigid plastic stents.



    • The various SEMS are equivalent in technical success, efficacy, and complication rates when used for malignant strictures.



    • The choice of a particular SEMS depends on device availability, familiarity and personal preference.



    • SEPS is approved for removability.



    • Benign strictures of the esophagus may be treated with either the Polyflex or the Alimaxx-E stents.



    • Migration rates are higher when treating benign strictures.





    Fistula formation





    • This typically occurs between the esophagus and the respiratory tract. Most common etiologies include esophageal carcinoma, bronchogenic carcinoma, radiation therapy, laser therapy, and esophageal stents. This latter occurrence is due to pressure necrosis at the edge of a previously placed SEMS (due to high radial expansive force).



    • Endoscopic placement of a covered SEMS is currently the primary and preferred form of therapy of malignant esophagorespiratory fistula with clinical success rates of 80–100%.



    • Patients with persistent ERF may benefit from parallel stent placement: placement of a stent in the esophagus in combination with another stent in the trachea and/or bronchi.




    Parallel stent placement





    • As mentioned above, this may be performed for non-healing esophagorespiratory fistula.



    • Esophageal cancer may invade/encroach the trachea causing dyspnea. In addition, mediastinal tumors causing extrinsic esophageal compression may also cause tracheal/bronchial compression. These patients are best treated with parallel stent placement because of risk of respiratory compromise. Place the tracheal or bronchial stent first.



    • Proximal esophageal stents may compress the trachea. A low index of suspicion for tracheal compression is advocated in these patients, especially if they develop dyspnea.



    • Complications, including fatal complications, occur more commonly with parallel stent placement because of tissue necrosis caused by the radial expansive force of both stents.




    Proximal esophageal carcinoma





    • Several small studies have shown that placing esophageal stents very close to the upper esophageal sphincter is feasible. The rate of efficacy is decreased, and there is a greater incidence of foreign body and globus sensation (8%) compared to more distal stents.



    • If one chooses to place a stent in the cervical esophagus, close to the upper esophageal sphincter, choose a stent with the following favourable characteristics:




      • Minimal to no foreshortening and a proximal release system to ensure precise deployment



      • Small body diameter of 18 mm or less to minimize globus sensation



      • Compliant characteristics in order to conform to the proximal esophageal anatomy



      • 1–2 mm should be left between the upper esophageal sphincter and the proximal margin of the stent.





    Extrinsic compression





    • Esophageal stents have been used for palliation of malignant esophageal obstruction due to extrinsic lesions with favorable results.



    • The degree of clinical improvement in such is significantly less than that in patients with malignant esophageal obstruction due to intrinsic lesions.




    Complications


    Early (or procedure-related) complications of esophageal stent placement occur in 10% of procedures and consist of chest pain, aspiration pneumonia, stent misplacement (can be minimized by choosing a stent 4 cm longer than the length of the stricture) and perforation. Late complications occur in 35–45% of patients and consist of gastrointestinal bleeding, development of ERF, stent migration, food bolus impaction, gastroesophageal reflux, and tumor overgrowth at either end of the stent. Stents placed across the gastroesophageal junction have higher complication rates when compared to stents placed in the mid-esophagus. In like manner, there is a statistically significant increased rate of life-threatening complications and associated increased mortality rate when placing stents in patients with a prior history of chemotherapy or radiotherapy. It appears that tissue integrity is compromised with administration of chemotherapy or radiation therapy, and this predisposes SEMS patients to a higher risk of life-threatening complications. Tumor ingrowth is a late complication that has been reduced with the advent of silicone or polyurethane covering, but unfortunately at the risk of increased stent migration (16% migration rate for covered SEMS vs 4% for uncovered SEMS). Treatment options for management of tumor ingrowth include laser therapy, injection therapy, electrocoagulation, photodynamic therapy, argon plasma coagulator, and placement of an overlapping second SEMS.



    Clinical Tips





    • When placing a stent across the gastroesophageal junction, choose a large diameter stent to decrease migration risk.



    • An antireflux stent may be useful.





    Duodenal stenting



    General concepts





    • Patients with gastric outlet obstruction were historically treated with gastrojejunostomy with or without choledochojejunostomy.



    • A recent systematic review of palliative stent placement versus open or laparoscopic gastrojejunostomy for the treatment of patients with malignant gastric outlet obstruction suggested that endoscopic treatment is the preferred modality in patients with short life expectancy (<6 months).



    • The two FDA-approved duodenal stents are uncovered and can be placed through the working channel of a therapeutic endoscope (need a working channel ≥3.8 mm).



    • It is frequently not possible to traverse the stricture with the endoscope since a therapeutic endoscope is usually warranted.



    • Duodenal stents are best placed under fluoroscopic guidance.



    • There is usually no need to aggressively dilate the stricture in order to minimize risk of perforation.



    • Duodenal stents are not used for benign disease.



    • Patients with malignant duodenal obstruction often have or are at risk for biliary obstruction. Consider placing a biliary SEMS prophylactically before placing a duodenal SEMS.



    • Duodenal strictures are dilated (18–22 mm) only if biliary drainage is to be performed, since access to the papilla requires the use of a large diameter therapeutic duodenoscope.




    FDA-approved expandable duodenal stents


    See Table 2 .



    Table 2

    FDA-approved expandable duodenal stents




























    Stent type Manufacturer Material Covering Deployment diameter (mm) Degree of shortening Features
    Wallstent Enteral Boston Scientific Cobalt-based alloy Uncovered 20, 22 40–50% TTS delivery, reconstrainable
    Wallflex Enteral duodenal Boston Scientific Nitinol Uncovered 22 30–40% Proximal flaring, TTS delivery, reconstrainable



    Technique of stent placement





    • The insertion procedure of a duodenal stent is similar to that of an esophageal stent ( Figs 4, 5 ).




      Figure 4


      Insertion of duodenal stent.



      Figure 5


      Duodenal stenting. Tumor ingrowth in a previously placed duodenal stent. A wire is placed across the stent under (A) endoscopic and (B) fluoroscopic guidance. A second, followed by a third stent is deployed (C). (D) The final radiographic image with three duodenal stents.

      (Courtesy of Dr Ian Penman.)



    • Patients with gastric outlet obstruction have high gastric residuals and suction of gastric contents should be performed if possible, to minimize aspiration risk and optimize visualization.



    • Patients should be in supine or prone position to optimize fluoroscopic visualization.



    • If a patient is deemed high risk for aspiration, consider endotracheal intubation prior to stent placement.



      Clinical Tips





      • The status of the biliary tree should be assessed before gastroduodenal stent placement.



      • Placement of SEMS across the papilla will render endoscopic biliary access difficult, if not impossible.





    • If the tumor is located in the proximal duodenum without involvement of the papilla, a stent that is long enough to cross the lesion should be chosen, but not excessively long which will prevent access to the papilla. Therefore, accurate assessment of the length and location of the malignant stricture is important.



    • The stricture may then be accessed with a standard biliary balloon catheter over a guidewire under fluoroscopic guidance. Injecting dye through the stricture may help delineate the length, geometry, and extension of the stricture.



    • The selected stent should be about 4 cm longer than the stricture.



    • Prior to discharge, patients should be advised to advance from liquids to solids as tolerated and to avoid leafy vegetables, which may result in stent occlusion.



    Clinical Tips





    • An expandable metal biliary stent should be placed before the duodenal stent is placed if there is known or impending biliary obstruction.



    • To treat biliary obstruction after placement of a duodenal stent, a percutaneous transhepatic approach is usually required.



    • Stenting of both the duodenum and the bile duct is the non-surgical equivalent of a traditional double surgical bypass (gastrojejunostomy and choledochojejunostomy).





    Outcome data (efficacy) and complications


    One systematic review that included 606 patients summarized the published evidence of the effectiveness and safety of gastroduodenal stenting. Technical success and clinical success were achieved in 97% and 89% of patients, respectively. There was no procedure-related mortality and serious complications (bleeding and perforation) were observed in 1.2% of patients. In addition, migration and obstruction (primarily due to tumor ingrowth) occurred in 5% and 18% of patients, respectively.


    Jejunal stents may also be placed. These can sometimes be placed with a pediatric colonoscope; however, augmented enteroscopy with double balloon, single balloon or spiral enteroscope ( Fig. 6 ) provide a stable platform for stent insertion.




    Figure 6


    Jejunal stent insertion using spiral enteroscopy. (A) Small-bowel obstruction with tumor. (B) Deployment of SEMS using Endo-Ease Discovery overtube. (C) Endoscopic image of deployed SEMS. (D) Radiographic image of deployed SEMS.

    (Courtesy of Dr Anne Marie Lennon, from Lennon AM, Chandrasekhara V, Shin EJ, Okolo PI. Spiral-enteroscopy-assisted enteral stent placement for palliation of malignant small-bowel obstruction. Gastrointestinal Endoscopy 2010; 71(2): 422-425.)



    Colonic stenting



    General concepts





    • All four FDA-approved colonic stents are SEMS.



    • All colonic stents currently in use are uncovered because the use of covered stents in the colon is associated with an unacceptably high migration rate.



    • Two SEMS can be placed through the scope (TTS) and the other two are non-TTS.



    • Few data exist on the use of colonic stents for the treatment of benign diseases of the colon.



    • Main indications for colonic stenting are:




      • Bridge to surgery in patients with colorectal cancer (CRC) who present with total or subtotal colonic obstruction.



      • Palliation of inoperable malignant colorectal obstruction.



      Box 3

      Rationale for colorectal stenting as a bridge to surgery





      • Of patients with CRC, 7–29% present with or develop colorectal obstruction.



      • Field contamination hazard exists with emergency surgery.



      • Patients are usually malnourished and have dilated colons, both of which increase the surgical risk.



      • Avoid colostomy: colostomy management is cumbersome to some patients, it worsens QoL, and its closure has significant morbidity and mortality of 37% and 7%, respectively.



      • Avoids multistep surgery.



      • Possible laparoscopic approach.



      • Preoperative colonoscopy to clear the colon of synchronous tumors and more proximal strictures.





    • Smaller diameter stents are appropriate for proximal colonic stenting because the stool is still liquefied and smaller diameter stents may carry a lower perforation risk. Larger diameter stents are more appropriate for distal colonic strictures to prevent solid stool impaction within the stent lumen



    • Enema preps suffice for patients with total colonic obstruction or distal colonic obstruction. All other patients require standard colonoscopy preparation.




    FDA-approved expandable colonic stents


    Table 3 .



    Table 3

    FDA-approved expandable colonic stents












































    Stent type Manufacturer Material Covering Deployment diameter (mm) Degree of shortening Features
    Ultraflex Precision Colonic Boston Scientific Nitinol Uncovered 25 25% Non-TTS, non-reconstrainable, proximal flaring
    Wallstent Enteral Boston Scientific Cobalt-based alloy Uncovered 20, 22 40–50% TTS delivery, reconstrainable
    Wallflex Enteral Colonic Boston Scientific Nitinol Uncovered 22, 25 30–40% TTS delivery, reconstrainable, proximal flaring
    Colonic Z-Stent Cook Endoscopy Stainless steel Uncovered 25 None Non-TTS



    Technique of stent placement ( Figs 7, 8 )





    • Placement of colonic stents is more technically demanding than esophageal and gastroduodenal stents. Endoscopic placement alone can be performed for traversable strictures. Because of the frequent complexity of colonic strictures, colonic angulations, and the presence of stool, the use of fluoroscopic guidance is advocated.



    • For endoscopic placement alone, a small calibre endoscope is used to traverse the stricture. The stricture can be carefully dilated to 12–14 mm if needed. The geometry and length of the stricture are then determined with the endoscope. Subsequently, the guidewire is placed through the stricture and the scope is withdrawn. Only non-TTS stents may be used since TTS stents do not fit into the therapeutic channel of a small calibre endoscope. The stent is then placed over the guidewire, the endoscope is positioned just distal to the lesion, and the stent is deployed under endoscopic guidance.



    • Combined endoscopic and fluoroscopic placement obviates passage of the endoscope across the stricture. A therapeutic channel endoscope and a TTS-stent may be used. A biliary balloon catheter is passed through the stricture over a stiff guidewire and water-soluble dye is injected to delineate the geometry and length of the stricture. The stent is then placed under endoscopic and fluoroscopic guidance as described previously.



    • The stent chosen should be 4 cm longer than the stricture.



    Clinical Tips





    • If the stricture lies within or close to an angulation, then the ends of the stent may be oriented towards the colonic wall after deployment, preventing adequate passage of fecal material through the stent. If this occurrence is anticipated, then it may be preferable to use a longer stent than expected to ensure that the ends of the stent are directed towards the lumen.



    • TTS-stents should be used for right sided lesions.





    Figure 7


    Insertion of colonic stent.



    Figure 8


    Colonic stent insertion. (A) Malignant colonic obstruction (B) that was palliated with placement of a self-expandable metal stent.



    Outcome data (efficacy) and complications





    • Table 4 summarizes pooled analysis from a 14-year data collection that included 1198 patients.



      Table 4

      Pooled analysis of technical and clinical success rates



































      Group Patients ( n ) Cumulative (%)
      Technical success Overall 1198 93.2
      Bridge to surgery 407 91.9
      Palliative 791 93.3
      Clinical success Overall 1198 88.6
      Bridge to surgery 407 71.7
      Palliative 791 91



    • SEMS may be used effectively to treat patients with malignant rectal obstruction within 5 cm from the anal verge (anal pain occurs in 62% of patients).



    • SEMS may be used effectively to treat patients with malignant proximal colonic obstruction (technical success 95%, clinical success 85%).



    • Colonic stents are generally less effective for palliation of colorectal obstruction due to extrinsic malignant obstruction.



    Clinical Tips





    • SEMS may be used effectively to treat benign colorectal obstruction with relief of obstruction in 95% of cases.



    • Serious complications occur in about 40% of patients, most of which occur 7 or more days after stent placement.



    • If SEMS are used for benign colorectal disease, surgery should be planned soon after stent placement (bridging).



    • See Table 5 for colorectal stent complications.



      Table 5

      Preoperative and palliative colorectal stents complications ( n = 826)





















      Mortality 0.3%
      Morbidity 5–10%
      Perforation 3%
      Migration 9%
      Bleeding/pain/tenesmus 10%
      Re-obstruction 9% (tumor ingrowth/overgrowth 74%, fecal impaction 20%, migration 6%)




    Further Reading


  • Baerlocher MO, Asch MR, Dixon P, et. al.: Interdisciplinary Canadian guidelines on the use of metal stents in the gastrointestinal tract for oncological indications. Can Assoc Radiol J 2008; 59: pp. 107-122.
  • Baron TH: Expandable gastrointestinal stents. Gastroenterology 2007; 133: pp. 1407-1411.
  • Baron TH: Expandable metal stents for the treatment of cancerous obstruction of the gastrointestinal tract. N Engl J Med 2001; 344: pp. 1681-1687.
  • Dormann A, Meisner S, Verin N, et. al.: Self-expanding metal stents for gastroduodenal malignancies: systematic review of their clinical effectiveness. Endoscopy 2004; 36: pp. 543-550.
  • Eloubeidi MA, Lopes TL: Novel removable internally fully covered self-expanding metal esophageal stent: feasibility, technique of removal, and tissue response in humans. Am J Gastroenterol 2009; 104: pp. 1374-1381.
  • Mougey A, Adler DG: Esophageal stenting for the palliation of malignant dysphagia. J Support Oncol 2008; 6: pp. 267-273.
  • Nathwani RA, Kowalski T: Endoscopic stenting of esophageal cancer: the clinical impact. Curr Opin Gastroenterol 2007; 23: pp. 535-538.
  • Sebastian S, Johnston S, Geoghegan T, et. al.: Pooled analysis of the efficacy and safety of self-expanding metal stenting in malignant colorectal obstruction. Am J Gastroenterol 2004; 99: pp. 2051-2057.
  • Tierney W, Chuttani R, Croffie J, et. al.: Enteral stents. Gastrointest Endosc 2006; 63: pp. 920-926.



  • Argon plasma coagulation



    Vikesh K. Singh
    Jean Marc Canard




    • Summary


    • 1

      General principles 179


    • 2

      Equipment 179


    • 3

      Technique 179


    • 4

      Clinical applications 181


    • 5

      Complications 183



    Key Points





    • Argon plasma coagulation (APC) is a non-contact monopolar electrocoagulation technique.



    • APC probes can direct high frequency current towards tissue in a parallel or perpendicular fashion.



    • The depth of coagulation is dependent on the properties of the target tissue, the generator power setting, the distance between the probe and tissue, and duration of current application.



    • Power settings of 40–60 W and gas flow rates of 1 L/min are used for superficial hemostasis and ablation of vascular ectasias. Power settings of 70–90 W are used for tissue ablation.



    • APC is used for the treatment of gastric antral vascular ectasia, angiodysplasia, radiation proctopathy, and residual adenomatous tissue seen after piecemeal colonic polypectomy.





    General principles


    Argon plasma coagulation (APC) is a non-contact monopolar electrocoagulation technique, initially used for endoscopic applications in the digestive tract in 1994 by Grund and Farin. APC is used primarily for superficial hemostasis and tissue ablation.


    The probe of the delivery catheter contains a tungsten electrode through which a high frequency electric current is delivered to the target tissue using ionized argon gas (argon plasma). This results in the coagulation of the target tissue. The depth of coagulation is dependent on the power of the electrosurgical generator, the distance between the probe and the target tissue, and the duration of application. The physical properties of the treated tissue also affects the depth of tissue injury. Treated tissue demonstrates three zones of effect. The outermost zone, closest to the probe, is the dessication zone followed by the coagulation and devitalization zone ( Fig. 1 ).






    Figure 1


    (A) The argon beam follows the path of least electrical resistance and; therefore, will direct itself away from treated tissue to adjacent areas of untreated tissue. This property allows administration of current in both a perpendicular and parallel manner from the tip of the catheter probe. (B) Three zones of effect: (1) dessication (2) coagulation (3) devitalization.



    Equipment


    APC requires a monopolar electrosurgical generator, argon gas source, gas flow meter, flexible delivery catheter, foot activation pedal, and grounding pads.


    There are two manufacturers of APC generators (Conmed, Utica, NY and ERBE Electromedizen, Tubingen, Germany). Power can be adjusted between 0 and 150 W and gas flow rates between 0.5 and 7.0 L/min. The flexible delivery catheters are disposable and are available in a 1.5 mm, 2.3 mm, and 3.2 mm diameters with lengths of 220 cm and 300 cm. The most commonly used is the 2.3 mm diameter, 220 cm long catheter. The wider diameter catheters are used if a larger treatment area is required. The 300 cm catheters are used for treatment of lesions in the small bowel during push enteroscopy. Catheters can direct current in a parallel or ‘forward firing’ versus perpendicular or ‘side firing’ manner, in relation to the longitudinal axis of the catheter. The ‘side firing’ probe can be used for lesions which are difficult to access, such as those located behind a fold or around a sharply-angled corner ( Fig. 2 ). The foot activation pedal synchronizes delivery of the current and argon gas which ionizes the argon gas and allows current to be delivered to the target tissue.








    Figure 2


    Role of APC in areas which are difficult to access. (A) APC is very useful for treating areas in the retroflexed position. It has the advantage over other modalities of not damaging the endoscope. (B) APC of the cardia. (C) APC is useful for inaccessible blind areas, e.g. behind a fold.


    Grounding pads are required as APC is a monopolar coagulation technique necessitating that the current circuit is completed via a return electrode.



    Technique





    • Patients requiring colonic APC should be given a full bowel preparation prior to the procedure, even if therapy is to only be directed to the rectum because there is a risk of explosion. It is also imperative to aspirate the gas that is released in the colon during an APC procedure as failure to do so can result in colonic distension.



    • Apply the grounding pad. Care must be taken in patients with cardiac pacemakers and defibrillators when using APC. The grounding pad should always be placed away from these devices.



    • Check the generator and gas flow settings are appropriate for the desired indication prior to administering APC ( Table 1 ).



      Table 1

      APC setting


































      Indication Power setting (W) Flow rate (L/min) Tips
      Radiation proctopathy 40–60 1–1.5 If there is extensive hemorrhage, set power to 60 W and wash/suction blood before therapy
      GAVE 40–100 2.0
      Angiodysplasia 40–60 2.0 For cecal angiodysplasias, consider submucosal injection of 2–3 cc of saline and/or dilute epinephrine (1 : 200 000) with a power setting of 50 W and gas flow rate of 2 L/min prior to APC treatment. Application of pulses should be 1 s in duration
      Post polypectomy 40–65 0.8–2.0 Use 50 W with short application duration (1–2 s) for right colon and 60–65 W for left colon
      Tumor palliation a 70–90 2.0 Limit to those patients who are not good candidates for other palliative modalities

      a For example, in the treatment of occluded esophageal stent, palliation of obstruction in inoperable esophageal cancer or palliation of inoperable gastric cancer. Also when it is impossible to put a stent when the cancer is developed near or on the sphincter superior of the esophagus because the upper part of the stent can ‘avoid deglutition’.




    • Flush the probe before firing. This should be followed by test firing the probe before inserting the probe into the operating channel of the endoscope.



    • Insert the probe until it protrudes slightly from the operating channel with at least one black mark on the probe visible to prevent injury to the tip of the endoscope.



    • The probe should be kept 1–2 mm from the target tissue. If the probe is at a distance greater than this, ionization of the argon gas will not occur. Probe should initially touch the target tissue and then withdrawn prior to firing to ensure the proper distance.



    • Take care to make sure that an actively firing probe does not touch the mucosa, as this increases the risk of perforation and allows for the passage of non-ionized gas into open blood vessels.



    • Avoid repeatedly firing in the same area as this increases the risk of perforation.



    • If an increased distance is required between the probe and the target lesion, increasing the power, as opposed to the gas flow rate, will increase the length of ionized argon gas arc. Alternatively, a ‘side-firing’ probe can be used, particularly if the target lesion is located lateral to the probe or is behind a fold.



    • Avoid contact with the mesh from a metal stent as the wire may melt.



    • Avoid contact with a clip, as conduction of current can cause secondary perforation (particularly in the duodenum).



    Clinical Tips


    How to decrease risk of perforation





    • Always apply APC under direct visual control.



    • Start with multiple, short activations before using long activations.



    • Direct contact of the probe with the mucosa increases the risk of perforation and should be avoided.



    • Avoid repeated treatment of the same area.



    • Avoid excessive insufflation by asking the nurse to monitor for abdominal distension and suctioning regularly.



    • Limit the power of the generator to the level required for adequate coagulation of the target tissue.



    • Patients undergoing APC in the colon, even on the rectum, MUST have a full bowel preparation.



    • Avoid contact with clips to avoid secondary perforation.





    Clinical applications



    Radiation proctopathy


    APC has been shown to be an effective treatment for gastrointestinal bleeding associated with radiation proctopathy in several case series studies ( Fig. 3 ).




    • Patients must have a full bowel preparation, even if only treating the rectum, as there is an increased risk of explosion in an unprepared colon.



    • Care should be taken to avoid treatment close to the dentate line.



    • Power settings of 40–60 W and gas flow rates of 1–1.5 L/min have been evaluated.



    • Treatments are repeated every 1–2 months, with between 1 and 3 sessions usually required.




    Figure 3


    Radiation proctopathy. (A) Rectum with active bleeding from radiation proctopathy. (B) Following APC.


    Complications include post procedure pain, particularly when treatment is administered close to the dentate line. Rare complications which have been reported include transient urinary retention, rectovaginal fistula, and rectal strictures. There are currently no randomized prospective trials comparing APC with laser and medical therapies.



    Vascular lesions


    APC is an effective treatment for gastric antral vascular ectasia (GAVE) ( Fig. 4 ) and angiodysplasia ( Fig. 5 ), and prevents recurrent bleeding associated with these lesions.




    Figure 4


    Classic appearance of gastric antral vascular ectasia.



    Figure 5


    APC treatment of angiodysplasia. (A) Small angiodysplastic lesion before coagulation. (B) Following APC.


    GAVE ( Fig. 4 ) is an uncommon cause for upper gastrointestinal blood loss associated with cirrhosis and other chronic diseases ( Box 1 ). Involvement of the antrum can be patchy or diffuse. Patients often present with iron deficiency anemia. Improvements in hemoglobin levels and a decrease in transfusion requirements are seen in most patients. However, recurrence can be seen in 30–40% of patients between 20 and 30 months after therapy, which often requires further APC treatment.




    • Power settings between 40 and 100 W have been used.



    • Treatments are repeated every 1–2 months, with between 2 and 3 sessions usually required.



    Box 1

    Conditions associated with GAVE





    • Cirrhosis.



    • Collagen vascular disease (e.g. scleroderma).



    • Ischemic heart disease.



    • Chronic renal failure.



    • Pernicious anemia.



    • Bone marrow transplant recipients.




    Angiodysplasias ( Fig. 5 ) can be found throughout the gastrointestinal tract and are effectively treated with APC. Angiodysplasias can be found throughout the gastrointestinal tract and are effectively treated with APC.




    • The 300 cm probes will often be required to ablate angiodysplasias of the mid and distal small bowel during push enteroscopy.



    • Successful ablation of angiodysplasia(s) is indicated by the presence of a white coagulum after treatment.



    • APC treatment of diffuse angiodysplasias require moving a probe in an side-by-side and up-and-down arc which is commonly referred to as ‘painting’ the lesion with short, 1–2 s applications.



    • For cecal angiodysplasias, consider submucosal injection with saline and/or dilute epinephrine prior to treatment to reduce the risk of perforation.



    • APC therapy significantly improves hemoglobin values and is associated with lower rates of overt bleeding in about 85–90% of patients.




    Treatment of remnant polypoid tissue after piecemeal resection of large colonic polyps


    APC has been shown to be effective in devitalizing any remnant polypoid tissue at the rim and base of a piecemeal polypectomy site. Polyps which are large (>1.5 cm), flat, extended, and/or located behind a fold or an angulated area of the colon often require piecemeal resection techniques. Patients undergoing APC have been shown to have significantly fewer recurrences. Treatment should be focused along the rim of the polypectomy site but short applications at the base can also be used. However, there has only been one small randomized study demonstrating these results.



    Other applications


    APC has been used for palliative debulking of obstructive tumors of the esophagus ( Figs 6, 7 ), stomach, ampulla, and rectum ( Figs 8, 9 ). While symptomatic improvement is seen in >90% of patients, multiple treatment sessions are often required. While there have been few randomized studies, a large series of patients with obstructive esophageal and cardia tumors underwent APC with maintenance of luminal patency in 64% of patients until death.




    Figure 6


    APC for the palliative treatment of an esophageal tumor. Start at the most distal extent of the tumor and work proximally.



    Figure 7


    (A) Esophageal cancer pre-treatment. (B) APC treatment of the tumor. (C) Esophageal cancer following treatment.



    Figure 8


    Palliative treatment of a tumor in the sigmoid colon. Start at the most distal extent of the tumor to avoid coagulation in the wrong direction.



    Figure 9


    APC treatment for palliation of rectal cancer. (A) Rectal cancer pre treatment. (B) After the first session of APC. (C) Prior to commencing second session of APC. (D) Following second session. (E) Appearance during treatment. (F) Appearance after the session. (G) Appearance before the last session. (H) Last session of APC. (I) Scar with complete destruction. As a result of this example, YAG laser has been replaced with APC.


    APC has also been studied as therapy for bleeding peptic ulcers but concerns center on its inability to seal a bleeding vessel and the risk of precipitating further bleeding, especially from arteries >1 mm. Another potential role for APC in the future may be for shortening or trimming metal stents which have become displaced over time to prevent perforation or bleeding.



    Complications





    • Perforation can occur with APC (0.2% in one large study), particularly when treating lesions in the right colon. It is associated with increased power setting, long duration of application, and short probe to tissue distance.



    • Abdominal distension is not uncommon as even a few minutes of application can lead to significant quantities of argon gas release.



    • Colonic explosion has been described in patients who had not undergone a full bowel preparation or if a fermentable, sugar-containing laxative is used prior to the procedure.



    • APC can also cause a neuromuscular stimulation which can sometimes be painful.



    • Rare complications include transient urinary retention, rectovaginal fistula, rectal strictures and subcutaneous empyema.



    Further Reading


  • Canard JM, Fontaine H, Vedrenne B: Electrocoagulation par plasma d’Argon: première expérience française rapportée [Argon plasma electrocoagulation: first French experience reported]. Gastroenterol Clin Biol 1997; 21: pp. A36.
  • Canard JM, Vedrenne B: Clinical applications of Argon plasma coagulation in gastro-intestinal endoscopy: has the time come to replace the laser?. Endoscopy 2001; 33: pp. 353-357.
  • Canard JM, Vedrenne B, Bors G, et. al.: Résultats à long terme du traitement des rectites radiques hémorragiques par la coagulation au plasma d’Argon [Long-term results of the treatment of hemorrhagic radiation proctitis by argon plasma coagulation]. Gastroenterol Clin Biol 2003; 27: pp. 455-459.
  • Farin G, Grund KE: Technology of argon plasma coagulation with particular regard to endoscopic applications. Endosc Surg Allied Technol 1994; 2: pp. 71-77.
  • Dumot JA, Greenwald BD: Argon plasma coagulation, bipolar cautery, and cryotherapy: ABCs of ablative techniques. Endoscopy 2008; 40: pp. 1026-1032.
  • Ginsberg GG, Barkun AN, Bosco JJ, et. al.: The argon plasma coagulator. Gastrointest Endosc 2002; 55: pp. 807-810.
  • Manner H: Argon plasma coagulation therapy. Curr Opin Gastroenterol 2008; 24: pp. 612-616.
  • Morris ML, Tucker RD, Baron TH, et. al.: Electrosurgery in gastrointestinal endoscopy: principles to practice. Am J Gastroenterol 2009; 104: pp. 1563-1574.
  • Postgate A, Saunders B, Tjandra J, et. al.: Argon plasma coagulation in chronic radiation proctitis. Endoscopy 2007; 39: pp. 361-365.
  • Selinger CP, Ang YS: Gastric antral vascular ectasias (GAVE): an update on clinical presentation, pathophysiology, and treatment. Digestion 2008; 77: pp. 131-137.
  • Suzuki N, Arebi N, Saunders BP: A novel method of treating colonic angiodysplasias. Gastrointest Endosc 2006; 64: pp. 424-427.
  • Vargo JJ: Clinical applications of the argon plasma coagulator. Gastrointest Endosc 2004; 54: pp. 81-88.



  • Management of ingested foreign bodies



    Jean-Christophe Létard
    Marcel Happi Nono




    • Summary



    • Introduction 186


    • 1

      Clinical assessment 186


    • 2

      Imaging 186


    • 3

      Timing of endoscopy 187


    • 4

      Equipment 187


    • 5

      Endoscopy technique 188


    • 6

      Complications 190


    • 7

      Ingestion of toxins 190



    Key Points





    • 80–90% of foreign bodies and food bolus impactions pass spontaneously.



    • Always assess for perforation.



    • Drug packets should never be removed by endoscopy.



    • Have a low threshold for seeking anesthetic input to protect the airway.



    • Test the instrument you are going to use to remove the foreign body before performing endoscopy.




    Introduction


    Removal of foreign bodies is a common procedure for gastroenterologists. In the majority of cases the type of foreign body ingested can be determined by a careful history or by speaking to relatives or friends.


    The majority (80%) of foreign bodies are ingested by children, with a peak between the ages of 6 months to 3 years. Prisoners, psychiatric patients, alcoholics, patients with a history of digestive surgery or malformations (rings or webs) and edentulous elderly patients are at risk of foreign body ingestion.


    The commonest sites for obstruction are the glottis, valleculae, larynx, cricopharyngeal muscle, aortic arch, lower esophageal sphincter, pylorus, ileocecal valve or anus or at areas associated with pathology (i.e. esophageal stricture).


    Once in the stomach, most foreign bodies pass through the GI tract without complication within 1–2 weeks ( Box 1 ). Exceptions to this rule are objects longer than 5 cm or wider than 2 cm, which may not pass through the pylorus or duodenum.



    Box 1

    Outcome of ingested foreign bodies





    • 80–90% pass spontaneously.



    • 10–20% require endoscopy.



    • <1% require surgery.




    If endoscopy is required it is successful in greater than 95% of cases. The majority of series report morbidity rates of less than 5% and usually 0%.



    Clinical assessment



    Foreign body lodged in the respiratory tract


    This should be suspected if the patient has difficulty breathing or has wheezing.



    Foreign body in the upper gastrointestinal tract


    The ingestion of a foreign body can cause retrosternal pain, odynophagia, dysphagia, hypersialorrhea and sometimes vomiting in the case of large, obstructive objects. Subcutaneous emphysema can occur with esophageal perforation, while peritonitis suggests small or large bowel perforation. Sharp objects, such as toothpicks, meat or fish bones, razors, lapel badges, dentures or needles, can cause bleeding or perforation.


    A high degree of suspicion is required in children or mentally impaired adults as 20–38% of children are asymptomatic, while up to 40% of children or non-communicative adults have no history of foreign body ingestion.



    Imaging


    Plain radiographs in two planes should be performed promptly. Anteroposterior and lateral radiographs of the chest and abdomen should be performed. This allows for localization of the foreign body and will also detect the presence of pneumomediastinum, pleural effusion or subcutaneous air, which are associated with perforation. Anteroposterior and lateral films of the neck and chest should be performed if there is a suspicion of a foreign body in the esophagus versus the trachea ( Fig. 1 ).


    Mar 5, 2019 | Posted by in GASTOINESTINAL SURGERY | Comments Off on Interventional endoscopy
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