Fig. 2.1
Tools for gastrointestinal dilation. a Savary–Gilliard dilator. b Maloney dilator. c balloon dilator
In addition to endoscopic standard equipment, a fluoroscopy unit should be available, even though many esophageal strictures, especially in the case of repeat dilations at the same site, can be dilated without fluoroscopic guidance. Small-caliber (pediatric) endoscopes can be useful in transversing a difficult stricture.
Technique
The etiology, length, and further characteristics of the site needing dilation have to be well evaluated before therapy. If a stricture should prove to be impassable even with a small-caliber endoscope, contrast matter can be applied via an ERCP catheter to depict the stenosis on fluoroscopy.
For the treatment of an esophageal stricture, the endoscope is passed through the stenosis into the stomach. A guide-wire is placed into the antrum or duodenum under endoscopic control (◘ Fig. 2.2a). In the case of an impassable stricture, the guide-wire can be advanced over the stricture into the stomach under fluoroscopic control. In this case, a soft guide-wire with a Terumo tip should be used.
After withdrawal of the endoscope (◘ Fig. 2.2b), the bougie dilator is introduced over the guide-wire using gentle pressure until the maximal caliber is passed over the stenosis (◘ Fig. 2.2c, d). The bougie should always be well lubricated for a smooth passage. If no resistance is felt, no dilation of the stricture site has occurred. On the other hand, no excessive force should be used.
The bougie is finally withdrawn carefully with simultaneous advancement of the guide-wire to prevent dislocation out of the stomach.
Fig. 2.2
Bougienage of an esophageal stricture. a Guide-wire placement. b Withdrawal of the endoscope. c Introduction of the bougie over the guide-wire. d Bougienage, repeat with larger bougies if indicated
To prevent complications, usually the «rule of three» is applied for the selection of appropriate bougie sizes: the caliber of the first bougie should be equivalent to the estimated diameter of the stricture, followed by a stepwise increase in bougie sizes. After moderate resistance is encountered for the first time, no more than three dilators of progressively increasing caliber should be passed in one session (i.e., widening of the stricture by 3 mm in one session).
An exception to this rule is the treatment of a symptomatic Schatzki ring. The single passage of a large-diameter bougie (16–20 mm) has been advocated for this classic indication, as bougienage aims to disrupt the ring consisting of mucosa and submucosa.
Traces of blood on the withdrawn bougie dilator are a sign of expected mucosal injury (◘ Fig. 2.3) and are not equivalent to a complication but should sound a note of caution.
Fig. 2.3
Esophageal stricture a before and b after bougienage
In the case of persisting or recurrent dysphagia, a repeat procedure should be scheduled in 3–7 days.
Outcomes and Safety
Dysphagia usually can be relieved regardless of the type of stricture, if a widening of the lumen to at least 13–15 mm is achieved.
For peptic stenoses, clinical success rates of 85–93% are reported with bougie dilatations to diameters of 13–20 mm. Significant predictors for recurrent dysphagia are an initial small diameter of the stricture, a hiatal hernia >5 cm, persisting heartburn after the procedure, and a high number of dilation sessions necessary to relieve dysphagia.
The use of PPI can lower the risk of recurrence in peptic stenosis. In general, non-peptic strictures appear to have an increased risk of recurrence within the first year post-procedure.
The major complications of bougienage in the esophagus are perforations, significant bleeding, and aspiration. Perforation is the most clinically significant complication and is estimated to occur in 0.1–0.4% of cases. A perforation should be suspected if intense or persisting pain is reported post-procedure or if dyspnea, tachycardia, subcutaneous emphysema or fever is observed. In those cases, a thoracic CT or an esophagogram with water-soluble contrast should be obtained.
Even though dilatation procedures (together with variceal sclerosing) in the esophagus have been associated with a higher incidence of bacteremia than any other endoscopic procedures, it is rarely clinically significant. The current guidelines of the DGVS (the German gastroenterology association) do not recommend routine antibiotic prophylaxis, as there is no scientific evidence as to its benefit in preventing infectious endocarditis (Egan et al. 2006, Siddiqui et al. 2013).
Bougienage of Anal Strictures
Anal or distal rectal strictures (e.g., Crohn’s-related or deep pelvic anastomotic) can be widened with the use of metal bougies.
A pre-procedure evaluation with a small-caliber endoscope is advisable to identify more proximal stenoses or inflammatory alterations. For bougienage in this setting, so-called Hegar dilators are commonly used. These are slightly curved stainless steel rods with a conic tip and a round profile (◘ Fig. 2.4). They are available in sets of various sizes, ranging from 3 to 18 mm. They are introduced with gentle pressure without the use of a guide-wire; the initial diameter is estimated by means of the digital rectal examination; the rule of three is applied accordingly. If the initial rectal examination is already painful, sedation during the procedure is recommended.
Fig. 2.4
Hegar’s dilators, sample sizes of 12, 14, and 16 mm
2.2.2 Dilation
Indications
Stricture dilation may be indicated in any accessible segment throughout the gastrointestinal tract if there is associated clinical impairment or if the passage of a larger instrument for further interventions is required.
Esophagus
Dysphagia is the indication for dilation of a benign esophageal stricture. Dysphagia secondary to a malignant stricture will usually only temporarily be alleviated by dilation and prompts further interventions (e.g., stent placement). The endoscopic standard therapy for achalasia is pneumatic balloon dilation.
Esophageal strictures can be categorized into two groups. Simple strictures are symmetric or concentric with a diameter >12 mm and allow for an easy passage of the endoscope. Complex strictures are tortuous, smaller than 12 mm in diameter, or cannot be passed with a diagnostic endoscope.
Empiric dilations of the esophagus without obvious structural pathologies have been reported. Taking into consideration the balance between possible major complications and questionable success rates, dilation for this indication cannot be recommended (Egan et al. 2006).
Stomach/Small Intestine
The most common indication in this segment is a gastric outlet stenosis due to various etiologies: peptic scarring, inflammatory conditions (Crohn’s disease, pancreatitis, etc.), NSAID-induced, corrosive damage, or iatrogenic after endoscopic resections. The majority of these strictures are located in the pylorus or the duodenal bulb. Anastomotic strictures after surgery are another principal indication (Kochhar and Kochhar 2011).
Biliary System
Dominant strictures of the biliary tract in primary sclerosing cholangitis (PSC) are an indication for biliary dilation. Benign or postoperative biliary and anastomotic strictures after orthotopic liver transplantation are amenable to balloon dilation but have to be treated with further stenting for sustained clinical success. The widening of malignant stenoses to allow for the placing of a stent or balloon dilation of the papilla (preferably after sphincterotomy) in preparation for stone extraction is a further indication (Siddiqui et al. 2013).
Colon
Colonic stricture associated with obstructive symptoms should generally be evaluated for endoscopic dilation. The various etiologies include inflammatory bowel disease (IBD), ischemia, anastomotic or radiogenic scarring, NSAID, neoplasia, and diverticular disease.
Predictors of clinical success after dilation are short strictures, anastomotic stenosis, and tight strictures <10 mm. Multiple strictures, complete obstruction, stricture length of >4 cm, associated fistulas in the stenotic area, malignancy, or recent surgery are arguments for primary surgery (Lemberg and Vargo 2007).
Devices
Dilators are made of inflatable thermoplastic polymers fixed to a catheter and can be inflated to a cylindrical shape (◘ Fig. 2.1c) using a handheld accessory device. By pressure injection of liquid (water/diluted radiopaque contrast) or air, the balloon is expanded to a specified diameter. Most balloon dilators are designed to pass through a 2.8-mm endoscopic working channel («through the scope,» TTS) with or without wire guidance. Large-diameter balloons for the treatment of achalasia are filled with air («pneumatic dilation») and cannot be passed through the working channel of an endoscope. They are placed using wire guidance.
TTS balloon dilators are available in various sizes and designs, usually with diameters 6–20 mm and balloon lengths 3–8 cm. Some designs allow for sequential dilation to multiple diameters, depending on the applied pressure. Achalasia balloons are available in standard sizes of 30, 35, and 40 mm.
From a practical point of view, it is a noteworthy detail that lower pressures are used for pneumatic dilation to treat achalasia than for the smaller TTS balloons. For this reason, pressures are commonly indicated in atmospheres (atm) on devices for TTS balloons and in «pounds per square inch» (PSI) for achalasia balloons. Both coiled and monofilament/coated guide-wires can be used for dilator guidance if the design provides sufficient lateral stability (e.g., Jagwire).
Technique: Esophagus
Pneumatic dilation for achalasia: by dilation of the lower esophageal sphincter (LES), a disruption of LES muscle fibers is intended to lower the sphincter’s resting pressure. A favorable diagnostic marker for clinical success is a post-procedure resting pressure of the LES of <10 mmHg, which can only be evaluated by manometry in the further clinical course. The dilation can be performed under direct endoscopic visualization or facilitated by use of fluoroscopic guidance, depending on the operator’s preference and experience. It is imperative that a complete esophagogastroduodenoscopy with detailed inspection of the cardia has been performed before the dilation, to rule out pseudoachalasia.
The concept of «graded dilation» has proved effective and safe: The LES is first dilated using a 30-mm balloon. If there is an unsatisfactory resolve of dysphagia, a further dilation to 35 mm is performed 4–8 weeks later, with a final dilation to 40 mm after a similar interval if necessary.
With fluoroscopy the dilation is performed as follows:
After placement of the guide-wire under endoscopic visualization and removal of the endoscope, the achalasia balloon (e.g., Rigiflex) is well lubricated and inserted over the guide-wire. Under fluoroscopic control, the balloon is advanced (◘ Fig. 2.5a), until the double radiopaque markers (signifying the center of the balloon) are projected on the crest-like demarcation between the «dark» thorax and «light» abdominal area, i.e., the balloon is placed at the level of the diaphragm.
First the balloon is inflated incompletely to adjust the position of the forming waist in the middle of the balloon (◘ Fig. 2.5b).
After appropriate centering over the stricture, pressure is applied preferably up to 7–10 PSI. The pressure is maintained until the waist is obliterated (the preferred endpoint) and optionally for a further 6–60 s (◘ Fig. 2.5c). Care has to be taken to keep the balloon into place over the stricture, because there is a tendency for aboral dislocation.
Finally, the balloon is completely deflated and removed together with the guide-wire.
Fig. 2.5
Dilation of an esophageal stricture. a Introduction of the balloon dilator over the placed guide-wire. b Positioning of the balloon under direct visualization, alternatively with fluoroscopic control. c Balloon inflation until obliteration of the waist
Without fluoroscopy the dilation comprises the following steps:
Placement of the guide-wire, removal of the endoscope, and introduction of the balloon as described above.
Then the gastroscope is reintroduced and positioned above the cardia, so that the balloon can be maneuvered across the stricture under direct visualization (◘ Fig. 2.5b).
The balloon is slowly inflated to 7–10 PSI. The dilated cardia can be observed through the balloon (◘ Fig. 2.5c).
The pressure is maintained until an ischemic ring at the tightest diameter of the cardia is noted (equivalent to the obliteration of the waist) or for 6–60 s.
Finally, the balloon is completely deflated and removed after the endoscope.
Care has to be taken to completely deflate the balloon before extraction.
Technique: TTS Balloon Dilators
TTS dilators can be used in the esophagus as an alternative to bougienage. Their use is usually preferred for complex strictures. Bougienage is as effective and more cost-efficient for simple strictures (e.g., Schatzki rings).
First, the length and further characteristics of the stricture are determined (with contrast via an ERCP cannula if required). Then a balloon dilator with appropriate size and length is selected.
If the stricture cannot be negotiated with the endoscope, a guide-wire is advanced into the antrum using fluoroscopy to avoid kinking of the balloon catheter while passing complex strictures. With simple strictures, the balloon can be cautiously placed under direct endoscopic guidance without a wire, and fluoroscopy is not required.
The balloon is inflated under vision. The appropriate inflation pressure (depending on the intended diameter according to manufacturer’s specifications) is held for 30 s or until a sudden drop in pressure is noted on the pressure gauge of the inflation system. A slow increase of the inflation pressure and positioning of the dilator directly at the tip of the endoscope reduces the likelihood of balloon dislocation.
Waist formation and its obliteration can be directly observed through the transparent balloon.
Finally, the balloon is completely deflated and withdrawn with the endoscope (◘ Fig. 2.6).
Fig. 2.6
Balloon dilation of pyloric stenosis. a Passage of balloon catheter over stricture. b Lnflation of balloon. c luminal view after dilation
Technique: Gastric/Enteral, Biliary System, and Colon
Dilation in these segments is performed in analogy to the technique described above. (For dilations of biliary strictures, see ► Chap. 4). The larger the selected dilation diameter, the more sustained the clinical response seems to be, at the expense of an increased perforation rate.
Special aspects and recommendations with regard to different segments of the GI tract are listed in the following table.
Dilations in Different Segments of the Gastrointestinal Tract
Stomach/Small Intestine
First dilation usually to 15 mm.
Ulcerations and active inflammations should be treated medically before dilation.
More cautious dilation in repeat sessions of tight strictures (interval approx. 7 days).
No dilation within 8 weeks after chemical burns.
Biliary System
Ampulla of Vater: balloon size depending on the width of the distal bile duct. Up to 15 mm possible after sphincterotomy.
Proximal CBD: not over 6 mm.
If no waist obliteration is observed after 30 s, repeat dilations may be attempted.
There is a risk of cystic duct dilation/perforation, especially in cases of low insertion of the cystic duct. The position of the guide-wire in the central bile ducts has to be ascertained before balloon inflation.
Colon
First dilation for anastomotic strictures and Crohn strictures: 15 mm.
More cautious approach for strictures induced by diverticulitis, ischemia, or radiation.
(Neoterminal) ileum: 10–12 mm. Repeat dilation to 15 mm in case of insufficient clinical response.
Outcomes and Safety: Esophagus
Balloon dilations of benign esophageal strictures have excellent short-term clinical results. Nonetheless, recurrence of dysphagia within the first year post-dilation occurs frequently, especially in the case of non-peptic strictures. Clinical response and complication rates are comparable to those achieved with bougienage (see above).
Balloon dilation can be considered the standard therapy for achalasia, as an alternative to operative myotomy. Performed as «graded dilatation» as described above, a European multicenter trial observed a success rate of 82% after 5 years with no significant difference to laparoscopic Heller myotomy (LHM) with Dor fundoplication (Moonen et al. 2016). Irrespective of operative or endoscopic treatment (with a tendency toward more favorable outcomes for LHM), relapses may become apparent in the further clinical course and warrant repeat interventions. Rates of significant gastroesophageal reflux of about 20% are to be expected after dilation as well as LHM with fundoplication.
A better outcome for dilation is to be expected for patients >45 years of age. Young men in particular have a tendency toward lower success rates after balloon dilation. Further unfavorable predictors for clinical success after dilation are a dilated esophagus and Type I or III achalasia according to the Chicago classification (Pandolfino and Kahrilas 2013).
Outcomes and Safety: Stomach/Small Intestine
Dilations of the pylorus for treatment of a gastric outlet stenosis have favorable short-term success rates of 70–80%. Divergent results are reported for sustained clinical response, with success rates between 30% and 100%. A consistent therapy with PPI as well as eradication therapy of helicobacter pylori seem to be predictors for a successful outcome.
It is noteworthy that for this indication, strikingly high perforation rates of up to 7% were reported. For this reason we recommend cautious dilation, not over 15 mm. Dilations of gastroenteric anastomotic stricture seem to have good response rates. Case series for fibrotic Crohn’s disease strictures report long-term success rates, with avoidance of surgery in 56–75% of patients.
Outcomes and Safety: Biliary System
Exclusive dilation of biliary strictures has no sustained clinical response and should be accompanied by additional therapy like stent implantation. Only with PSC-induced dominant strictures is the placement of a stent of no additional use.
The dilation of the sphincter of Oddi as an alternative to endoscopic papillotomy is associated with an increased rate of pancreatitis. A large-caliber dilation after sphincterotomy has a success rate of 98% with regard to removal of large biliary stones, with a low complication rate (post-ERCP pancreatitis 1.2%).
Outcomes and Safety: Colon
Various uncontrolled case series have observed good effectivity of the dilation of benign colorectal strictures, with reported complication rates of 0–10%.
Excellent short-term results are reported for strictures in Crohn’s disease, but data for long-term avoidance of surgery are similarly divergent as described above for gastric/enteral strictures (Endo et al. 2013).
Outcomes and Safety: Additional Techniques
Incisions Electrosurgical incisions of esophageal or colonic strictures using a sphincterotome or needle-knife have been described by different work groups. Performed in addition to balloon dilation, increased clinical success rates are claimed. Evidence for the superiority of this procedure is rare, with the exception of the incisional treatment of Schatzki rings. For this indication, incisional therapy seems to produce comparable results to bougienage.
Steroid injections There is an ongoing controversy over the role of adding intralesional steroid injection to dilational therapy. Data from controlled trials predominantly suggest a lowered relapse rate after additional steroid injection, especially with regard to strictures in Crohn’s disease. On the contrary, steroid injections were not found to be effective with possible negative side effects in anastomotic strictures.
In our opinion, the injection of steroids in combination with dilation is a noteworthy treatment option for refractory benign strictures of peptic or inflammatory origin. A practicable approach to this technique is to dilute 40 mg/ml triamacinolone 1:1 with saline. Then, 0.5 ml aliquots are injected into each quadrant at the edge of the lesion (Di Nardo et al. 2010).
2.3 Stenting
In medical practice, stents are devices used to maintain or restore luminal patency of hollow organs, vessels, or ducts. In gastroenterology, semirigid plastic stents are distinguished from self-expandable stents. Tubelike plastic stents are generally only used in the biliary/pancreatic system and are placed over a guiding catheter or are pushed directly over the guide-wire in case of small-caliber stents. Plastic stents are available in different designs (e.g., straight or pigtail) and in sizes up to 12 French.
Self-expandable stents consist of mesh cylinders that are packaged in a compressed form on a delivery catheter. Once deployed, they exert self-expanding forces until reaching a predefined diameter (◘ Fig. 2.7). Sustained high radial forces then effect an appropriate widening of strictures and anchoring to surrounding tissue. Self-expandable stents are most commonly composed of metal alloys (SEMS, self-expandable metal stents) such as nitinol.
