Interventional endoscopy

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CHAPTER 7 Interventional endoscopy

7.1 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.

1 Clinical and endoscopic assessment

1.1 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.

• 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.

1.2 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.

• 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.

3 Endoscopic techniques

3.1 General principles

3.1.1 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).

• 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).

• 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.

Figure 1 Radial and longitudinal forces. Bougies are associated with longitudinal dilation forces (A), while balloon dilation is associated with radial dilation forces (B).

Figure 2 Bougies.

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.

3.1.2 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).

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

• 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.

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).

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).

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.

3.2 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.

3.3 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.

3.4 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.

3.5 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.

4 Complications

• 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%.

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.

1 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.

1.2 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.