10 Endoscopic Complications
Daniel Blero and Jacques Devière
10.1 Introduction
An endoscopic complication can be defined as an adverse event that requires a deviation from the initial plan for diagnosis and/or treatment, and this adverse event can be qualified as severe when it prolongs hospitalization and/or results in an unscheduled hospital admission. 1 The frequency of endoscopic complications is likely to increase in proportion to the indications and complexity of therapeutic procedures. The best way to prevent complication is to carefully analyze procedural indications and avoid unnecessary invasive examinations. Gastrointestinal (GI) endoscopy is a discipline evolving quickly within a multidisciplinary environment with paradigm changes such as the development of alternative, noninvasive diagnostic techniques, for example, magnetic resonance cholangiopancreatography (MRCP), which has entirely replaced diagnostic endoscopic retrograde cholangiopancreatography (ERCP) for imaging the biliopancreatic tract. With an increasing complexity of endoscopic procedures, the need for extensive knowledge of techniques and accessories has become paramount, and it is now clear that many of these procedures must be concentrated in specialized referral centers. Acquiring and maintaining experience in a multidisciplinary environment is essential to select the best procedure for a specific indication and to consequently reduce the risk of adverse events. Now that therapeutic endoscopy offers even more alternatives to open surgery, it is also important to disseminate information about the outcomes of these procedures in order to avoid inappropriate therapeutic approaches to manage known or suspected complications. For example, postprocedural management following submucosal and transmural endotherapy may result in imaging findings of incidental free air that may be inappropriately managed with aggressive surgery. 2
Preprocedural patient education and informed consent (see Chapter 3) are paramount. Standardization of treatment, organization of the therapeutic endoscopy team and its training, and adherence to guidelines are also essential in order to minimize, prevent, and adequately manage adverse events. The most frequent complications of diagnostic and therapeutic endoscopy are reviewed in this chapter. Different modalities of medical, endoscopic, and surgical management are also considered.
10.2 General Considerations
10.2.1 Cardiopulmonary and Sedation-Related Events
A cornerstone for proper performance of endoscopy is that the selection, and the monitoring of sedation should commensurate with the planned procedure. Cardiopulmonary adverse events account for up to 50% of severe morbidity and mortality related to GI endoscopy. 3 , 4 These adverse events range from clinically insignificant oxygen desaturation to clinical dysrhythmias, oversedation, aspiration pneumonia, respiratory failure, myocardial infarction, and shock. Many of these adverse events are linked to inappropriate sedation levels considering the type of procedure and the status of the patient, but they may also be associated with other adverse events such as bleeding, sepsis, and perforation.
Before undertaking moderate sedation (see Chapter 4), the patient’s medical and surgical history, baseline medications with a particular focus on antithrombotic agents, and drug allergies must be assessed. The American Society of Anesthesiologists (ASA) score is a useful predictor of procedural sedation risk. Other risk factors include age, type of anesthesia, inpatient status, emergency procedure, and trainee involvement. Patients should not temporarily discontinue their cardiovascular medications except for antithrombotic agents when high-risk bleeding procedure is performed (see ▶Table 10.1), 5 and this decision should be undertaken with advice from other specialists (cardiology, neurology, etc.) in patients at high risk for thrombosis.
Pharyngeal anesthesia is usually recommended when no or minimal sedation is administered. It should be used with caution or avoided in nonintubated patients with suspected gastric outlet obstruction or gastroparesis, and in the presence of active upper GI bleeding as it increases the risk of aspiration pneumonia. 3 Pre-oxygenation of patients with ischemic cardiovascular disease, as well as administration of supplemental oxygen during the procedure to avoid ischemic events, is recommended. All patients must be monitored using pulse oximetry before, during, and after the examination and continued until full recovery. Managing and avoiding cardiopulmonary adverse events requires competency in basic life support, knowledge of the patient’s underlying medical status, and pharmacological properties of the drugs used and their reversal agents.
10.2.2 Infection
Although rare, 6 infections can result from the transmission of microorganisms through the endoscope from one patient to another or (even more rarely) through reprocessed devices, from the translocation of bacteria from the endogenous digestive flora through a tear or perforation in the mucosa, from contamination of a sterile compartment by patient’s GI flora (i.e., typically during ERCP in the presence of obstructed ducts and inadequate drainage), or by the transmission of microorganisms from patients to personnel of the endoscopy unit (and vice versa).
All reported cases of patient-to-patient transmitted infections were due to failure to properly follow multisociety guidelines for disinfecting and reprocessing flexible endoscopes, 7 , 8 first published in 2003. It must be noted, however, that this type of infection remains of major importance as recently illustrated when contamination of duodenoscopes not adequately designed to allow proper disinfection resulted in severe iatrogenic infections. 9
Regarding prevention of bacterial translocation during endoscopy, prophylactic antimicrobial regimens are recommended in cases of suspected incomplete biliary drainage, puncture of fluid collections or cysts, percutaneous endoscopic gastrostomy placement, and in patients with variceal bleeding. In some cases, prophylaxis entails single-dose administration before treatment, while in others it may need to be continued, such as in patients with inadequately drained bile ducts or those with variceal bleeding. New techniques involving transmural access, such as endoscopic ultrasound (EUS)-guided biliary drainage, peroral endoscopic myotomy (POEM), and gastric transmural therapy, also require antibiotic prophylaxis with or without continued treatment. Unfortunately, prospective evidence for these indications is lacking.
The protection of endoscopy personnel from infection/contamination by patient body fluids should be instituted and followed according to institutional universal exposure educational guidelines and postexposure management. 10
10.3 Upper Gastrointestinal Endoscopy
10.3.1 Diagnostic Upper Gastrointestinal Endoscopy
Diagnostic upper GI endoscopy is usually considered to be a safe procedure, with overall complication and mortality rates at 0.13 and 0.004%, respectively. 11 Procedure-induced Mallory–Weiss tear occurs in < 0.5% of diagnostic endoscopies and is generally not associated with significant bleeding. 12 Bleeding after mucosal biopsy is rare in the absence of thrombocytopenia, coagulopathy, or portal hypertension. Biopsies can be safely performed in patients with a platelet count > 20,000/mm. 3 , 13 Perforation secondary to diagnostic upper GI endoscopy is extremely rare, with an estimated frequency of < 0.03%. 3 Risk factors for perforation include endoscopist inexperience, presence of cervical osteophytes, Zenker’s diverticulum, pharyngeal pouches, and esophageal stricture. Eosinophilic esophagitis is a recognized risk for mucosal tearing and perforation during diagnostic procedures. 14 ,
10.3.2 Therapeutic Upper Gastrointestinal Endoscopy
Therapeutic upper GI endoscopy has dramatically increased over the last 10 years and is associated with a much higher rate (approximately 10 times) of adverse events than diagnostic procedures. 15
Stricture and Achalasia Dilation
Dilation of esophageal strictures and achalasia pneumatic dilation are associated with specific complications including perforation, bleeding, and bronchial aspiration. Bronchial aspiration can be prevented by endotracheal intubation, which is recommended in patients with comorbidities, although it is also associated with specific adverse events. 16 Perforation risk varies with indication and technique used. Up to 4% risk has been described for pneumatic dilation of achalasia. 17 It can be reduced by starting with a balloon diameter of 30 mm and not dilating greater than 35 mm. 17 With the advent of POEM, the use of pneumatic dilation is likely to decrease. 18 The risk of perforation when dilating malignant and caustic strictures is twofold compared with benign (peptic) strictures. 19 Complex strictures (defined as an asymmetry, < 12 mm in diameter, or endoscopically impassable) are also associated with increased rates of complications. 19 Another established risk factor for perforation is the level of operator experience. The risk of perforation during dilation is four times higher for trainees who have performed fewer than 500 upper GI endoscopies. 3 Most perforations occur at the first session of dilation. 20 Three separate studies failed to show that bougie dilators are safer than balloon dilators in patients with benign strictures. 21
Stent Insertion
Self-expandable metal stent (SEMS) placement is a method for palliating malignant dysphagia and malignant tracheoesophageal fistula. 22 , 23 SEMS can also be used to close upper GI fistulas in benign conditions. 24 , 25 Unfortunately, complications are frequent (20–40%). 26 Thoracic or epigastric pain is common after SEMS placement but is usually transient. Acute perforation is rare unless prior dilation was required. The risk of late perforation and bleeding seems to be higher with larger stents, and particular caution should be taken when stenting the gastroesophageal junction where asymmetrical pressure against the esophageal wall may precipitate ulceration, perforation, and/or bleeding. The use of larger stents, however, does decrease the rate of other adverse events, such as stent migration and tumor ingrowth. 26 After placement of a stent across the gastroesophageal junction, proton pump inhibitor (PPI) use and postural precautions are mandatory. The efficacy of antireflux stents has not been established. 27
Late complications of stenting also include relapsing stenosis due to tissue hyperplasia (in the uncovered parts of partially covered stents) and tumor overgrowth. If the stent is placed for a benign indication, tissue hyperplasia may be treated by temporary placement of a second fully covered stent inside the first one, which will pressure necrose the inflammatory tissue and allow stent removal. 24 , 25 , 26 Following SEMS removal, secondary fibrotic strictures at the proximal or distal ends may occur, and are usually easily managed with dilation.
Polypectomy, Endoscopic Mucosal Resection, and Endoscopic Submucosal Dissection
Polypectomy, endoscopic mucosal resection (EMR), and endoscopic submucosal dissection (ESD) are commonly associated with bleeding, although most bleeding is intraprocedural, controlled endoscopically, and is not clinically relevant. Perforation occurs in 3% of esophageal resections and in 1% of gastric resections. 28 , 29 , 30 Cicatricial strictures are a late complication that mainly occur after circumferential esophageal resection. 31 Delayed bleeding after esophageal or gastric EMR/ESD is uncommon (< 5%). 28 , 30 To prevent delayed bleeding, some authors recommend coagulation of all visible submucosal vessels during the procedure for gastric resections, but this and second-look endoscopy are not routinely recommended. 32 PPI therapy is usually prescribed after the procedure. Delayed bleeding occurs more frequently after duodenal mucosal resection compared with esophageal and gastric resection, with bleeding rates ranging from 4 to 33%. Some authors suggest closure of the mucosa after resection with placement of multiple clips. 33
In the last two decades, ablative therapies (such as argon plasma coagulation, photodynamic therapy, and mainly radiofrequency ablation) have emerged for the treatment of premalignant or early superficial malignant lesions, and as palliative therapy for some advanced tumors. Photosensitivity is a specific complication associated with the use of photodynamic therapy, but can also result in the development of strictures, especially when applied in the esophagus. 34 , 35 Stricture formation as a late complication can occur after circumferential radiofrequency ablation for treatment of dysplastic Barrett’s esophagus.
Hemostasis of Nonvariceal Bleeding
Hemostasis of nonvariceal bleeding includes a combination of injection therapy and thermal or mechanical therapy. Although adrenaline injection (0.1 mg/mL) does not result in complications, injection of sclerosants (such as polidocanol, ethanolamine, or absolute alcohol) should be avoided as they do not control bleeding 36 and could lead to life-threatening tissue necrosis. 37 Coaptive coagulation can be obtained by the use of bipolar coagulation or heater probes. Perforation rates with these devices range from 0 to 2%, and are increased when treatment is repeated. 38 , 39 Monopolar probes have higher rates of perforation and have largely been abandoned.
Endoscopic tools available to treat esophageal variceal bleeding include band ligation, variceal obliteration, and sclerotherapy. Endoscopic band ligation is as effective as sclerotherapy with fewer and less severe complications (perforation rates: < 0.7 vs. 2–5%; superficial ulceration rates: 5–15 vs. 70–90%, respectively) and a major impact on overall mortality. It has become the preferred technique for acute bleeding, and primary and secondary prophylaxis of variceal bleeding. 40 , 41 , 42 Injection of cyanoacrylate is more effective than endoscopic band ligation for gastric variceal bleeding but is not without risks, such as embolization, which occurs in 2 to 5% of cases. 43 Pulmonary embolism is usually limited and with marginal clinical consequences. Paradoxical embolism may occur (especially in unsedated patients who have transient opening of the foramen ovale) with lethal outcome.
Removal of Foreign Bodies
Adverse event rates encountered during the removal of foreign bodies can reach 8%. 44 The most common complication is aspiration pneumonia, which can be prevented by endotracheal intubation, sometimes difficult in an emergency situation. Another major complication is mucosal tearing, which occurs during retrieval of sharp objects through the esophagus. Tearing can be prevented by using a protector hood at the distal extremity of the scope or by the use of an overtube. However, an overtube itself can induce mucosal tearing and perforation of the esophagus. Its use should be restricted to patients placed in the left lateral decubitus position in order to ensure neck overextension during overtube insertion.
10.3.3 Management of Upper Gastrointestinal Perforation
While perforation is a feared and well-known complication of upper GI endoscopy, its management has evolved and is no longer considered an absolute indication for surgery. Endoscopic closure of small perforations (< 2 cm) recognized during the procedure can be achieved using through-the-scope (TTS) clips. Larger over-the-scope closing devices may be useful in selected situations. 45 , 46 SEMSs (partially or fully covered) have also been used to treat large perforations, especially those occurring after dilatation. 24 , 26 An algorithm for the management of upper GI perforation is presented in ▶Fig. 10.1. 27 , 45 , 47 Since prompt recognition and management of perforations is paramount, a careful examination at the end of a procedure in high-risk situations can be performed with injection of water-soluble contrast agents under fluoroscopy, if possible.
In the case of suspected delayed esophageal perforation (characterized by persistent or increasing pain, fever, respiratory distress, and hemodynamic instability), a water-soluble contrast radiographic study is the examination of choice. Alternatively, computed tomography (CT) scan of the neck and chest can be used. Endoscopic closure can be performed in concert with drainage of any fluid visualized collection, when possible. 24
In the case of gastric or duodenal perforation, the same principles are applicable, but endoscopic closure mainly relies on the use of clips combined with gastric aspiration. 45
10.3.4 Management of Upper GI Bleeding
Bleeding during therapeutic endoscopy is part of the procedure especially during polypectomy, EMR, or ESD. Immediate and late bleeding can be managed using coagulation forceps (preferred during EMR or ESD) or clips. Bleeding occurring after esophageal stenting, especially when occurring late after the initial procedure, should always be evaluated by proper imaging, given the potential risk of esophago-aortic fistulas. 48
10.4 Small Bowel Endoscopy
Various endoscopic techniques can be used to explore the small intestine. These include push enteroscopy, single and double-balloon enteroscopy (SBE and DBE, respectively), spiral enteroscopy, and video capsule endoscopy. The most widely available published data concern DBE and video capsule endoscopy. The most common adverse events associated with DBE include perforation, bleeding, pancreatitis, and adverse events related to sedation. The rate of adverse events associated with DBE ranges from 0.4 to 0.8% for diagnostic procedures and 3 to 4% for therapeutic procedures. 49 , 50 The rate of pancreatitis associated with the antegrade DBE is consistently reported to be around 0.3%. The mechanisms of pancreatitis remain poorly understood. Pancreatitis may be prevented by avoiding inflation of the balloon at the duodenal level. 51 Management of perforation following enteroscopy usually requires prompt surgical intervention.
The main complication of video capsule endoscopy is capsule retention (frequency 1–2%). 52 Retention is more common in cases of stenosis, especially those associated with Crohn’s disease. The identification of a radiological abnormality of the small bowel is associated with a risk of capsule retention of 15.4%, usually requiring surgical or DBE exploration for retrieval. 53
10.5 Colonoscopy
Colonoscopy is the gold standard for diagnosis of colorectal cancer and treatment of colorectal polyps. The rate of significant adverse events for diagnostic colonoscopy ranges from 0.02 to 0.07%. 54 The bowel preparation itself, if performed with sodium phosphate, may be associated with hypovolemia, hyperphosphatemia, and eventually death. Age, preexisting renal failure, and the use of nonsteroidal anti-inflammatory drugs (NSAIDs) are risks factors for this complication. 55
10.5.1 Perforation
The reported frequency of this most feared complication varies in the literature. In a multicenter, prospective survey of 9,223 colonoscopies performed in England, the perforation rate was 0.11% for diagnostic and 0.21% for therapeutic colonoscopy. 54
Three different mechanisms exist by which colonic perforation might occur during endoscopy: pneumatic perforation of an already weakened colonic wall; mechanical perforation owing to excessive pressure by the scope against the colonic wall; and posttherapeutic colonoscopy perforation, which can occur when the colonic wall has been made fragile by polypectomy, EMR, ESD, and/or coagulation during therapeutic colonoscopy. Following the results of a report of 183 colonic perforations, the most predominant site of perforation was the sigmoid colon (72%), followed by the ascending and descending colon (8.6% each), the rectum (6.9%), and the transverse colon (3.4%). 56 Risks factors for perforation during colonoscopy include the following: therapeutic colonoscopy (polypectomy, EMR, stricture dilation, and argon plasma coagulation use), age > 75 years, diverticular disease, previous intra-abdominal surgery, colonic obstruction, and female gender. 57
Intraprocedural perforations occurring during EMR or ESD (the latter in approximately 30% of cases) 58 are frequently recognized immediately, with the “target sign” on the resection specimen useful. EMR perforation risk factors include transverse or right colon location, en-bloc resection, and presence of high-grade dysplasia or submucosal cancer in the resected specimen. 59 In most situations, the recognition of peritoneal structures is obvious, but a sudden lack of insufflation and/or acute pain are signs that perforation has occurred. 56 In half of cases, perforations are < 2 cm in length and are not easily recognized. This is why, the diagnosis is often delayed (from 1 hour to weeks after the procedure). 56 An overt perforation with associated peritonitis is easy to diagnose, while patients having localized peritoneal signs due to minimal perforation, sometimes delayed and known as “the postpolypectomy syndrome” or “transmural burn syndrome,” may be more challenging to diagnose. The clinical outcome of postpolypectomy syndrome is usually favorable with conservative treatment. 58 In any case of suspected perforation, an abdominal CT scan is the preferred examination for differentiating colonic perforation from postpolypectomy syndrome, which is characterized by the absence of diffuse air leak.
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