INTRODUCTION — Evaluation of the small bowel is difficult due to its length, intraperitoneal location, and contractility. Methods used to evaluate the small bowel include push enteroscopy, video capsule endoscopy, and intraoperative enteroscopy. These techniques all have advantages and limitations:

●Push enteroscopy has both diagnostic and therapeutic capabilities, but typically only examines that part of the small bowel that is 50 to 150 cm distal to the ligament of Treitz.

●Video capsule endoscopy is capable of examining the entire small bowel, but lacks therapeutic capacity.

●Intraoperative enteroscopy permits examination of the entire small bowel and therapeutic interventions, but is much more invasive.

Alternative endoscopic approaches have been developed to overcome these limitations. Deep small bowel enteroscopy permits visualization and interventional therapy throughout the small bowel by using insertion techniques that pleat the small bowel onto an overtube. The techniques used for deep small bowel enteroscopy limit stretching of the small bowel (as occurs with push enteroscopy), permit better transmission of maneuvers designed to position the tip of the enteroscope, and stabilize the enteroscope, thereby facilitating therapeutic interventions.

Options for deep small bowel enteroscopy available in the United States include:

●Double balloon enteroscopy (DBE)

●Single balloon enteroscopy (SBE)

●Spiral enteroscopy

All three systems can be used for diagnostic and therapeutic applications. One difference among the systems is that DBE and SBE can be used with an anterograde or retrograde approach, while spiral enteroscopy is limited to an anterograde approach. Selection of a system for deep small bowel enteroscopy is generally based on hospital resources, clinician preference, and availability.

An additional option available outside the United States is the NaviAid Balloon Guided Endoscopy Device.

The first report of DBE appeared in 2001 [1], followed by the introduction of a dedicated system for DBE in 2003 [2]. Use of DBE has subsequently grown worldwide, and the first international workshop on DBE was held in Japan in August 2006. SBE became commercially available in 2007 [3], and a spiral enteroscopy system was approved by the US Food and Drug Administration for deep small bowel enteroscopy in 2008.

This topic will review the indications, techniques, and complications of balloon-assisted enteroscopy and spiral enteroscopy. Wireless video capsule endoscopy is discussed elsewhere. (See "Wireless video capsule endoscopy".)

INDICATIONS — Deep small bowel enteroscopy has multiple diagnostic and therapeutic applications, the most common being the evaluation of suspected small bowel bleeding [4]. (See "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)".)

Wireless capsule endoscopy is often preferred as an initial diagnostic test because it is noninvasive, well tolerated, and can view the entire small bowel [5]. However, deep small bowel enteroscopy is required in some patients such as those with findings that require biopsy or therapeutic intervention. Deep small bowel enteroscopy may also be preferred when a small bowel stricture is suspected since wireless capsule endoscopy in such patients is associated with an increased risk of capsule retention. (See "Wireless video capsule endoscopy", section on 'Capsule retention'.)

Diagnostic applications — Diagnostic applications for deep small bowel enteroscopy include:

●Evaluation of suspected small bowel bleeding [5]

●Evaluation and tattooing of suspected small bowel malignancies (eg, adenocarcinoma, lymphoma, GI stromal tumors, metastatic tumors) or abnormal findings on other imaging studies [6-12]

●Evaluation of suspected nonsteroidal anti-inflammatory drug-induced small bowel injury [13-16]

●Evaluation of suspected or established small bowel Crohn disease [17]

●Evaluation of refractory celiac disease [18,19]

●Detection of polyps in patients with polyposis syndromes such as familial adenomatous polyposis or Peutz-Jeghers syndrome [20]

●Examination of the gastric remnant in patients who have undergone Roux-en-Y gastric bypass [21,22]

●Diagnostic endoscopic retrograde cholangiopancreatography (ERCP) in patients with Roux-en-Y anatomy [22-24]

Therapeutic applications — An advantage of deep small bowel enteroscopy compared with capsule endoscopy and radiologic methods to visualize the small bowel is the ability to perform a wide variety of therapeutic interventions [25-32]. Therapeutic applications for deep small bowel enteroscopy include:

●Treatment of gastrointestinal bleeding (eg, angiodysplasia)

●Small bowel polypectomy

●Stricture dilation

●Stenting of small bowel obstructions

●Foreign body retrieval (eg, retained video capsule) [33,34]

●Endoscopic mucosal resection [35]

●Placement of direct percutaneous jejunostomy tube

●In patients with Roux-en-Y reconstructions (figure 1), placement of a percutaneous endoscopic gastrostomy (PEG) tube, ERCP with lithotripsy, dilatation of a biliary stenosis, and/or stent placement [22,36-39]

Advanced techniques — Novel approaches involving balloon-assisted enteroscopy continue to be reported. These include a modified double balloon enteroscopy (DBE) technique to access the proximal side of a stricture in the distal colon (anterograde colonoscopy) by using a long transnasal decompression tube as a guide [40], balloon-assisted intubation of the ileocecal valve to facilitate retrograde DBE [41], and balloon dilation of obstructing small bowel strictures [42].

CONTRAINDICATIONS — In general, patients deemed fit to undergo endoscopic procedures are candidates for deep small bowel enteroscopy. However, some authors suggest that surgically altered gastrointestinal (GI) anatomy (eg, an ileoanal or ileocolonic anastomosis or an ileostomy) should be a relative contraindication because of a higher perforation rate [3]. (See 'Complications' below.)

Because of the risk of perforation, we suggest that the examination be carried out cautiously by providers who have significant experience with these procedures when patients with surgically altered GI tract anatomy require deep small bowel enteroscopy (eg, a patient who has undergone Roux-en-Y gastric bypass who needs an endoscopic retrograde cholangiopancreatography).

In addition, the balloons used for double balloon enteroscopy (though not for single balloon enteroscopy) are latex and should not be used in patients with latex allergies. (See "Latex allergy: Epidemiology, clinical manifestations, and diagnosis".)

BALLOON-ASSISTED ENTEROSCOPY — Balloon-assisted enteroscopy includes double balloon enteroscopy (DBE) and single balloon enteroscopy (SBE). While similar, the systems vary with regard to whether a balloon is attached only to the overtube (SBE) or also to the tip of the enteroscope (DBE), resulting in differences in the techniques used to perform the procedures. Limited data suggest that the systems have similar efficacy. (See 'Efficacy' below and 'Single balloon enteroscopy' below.)

Systems are also being developed to permit balloon-assisted enteroscopy using a balloon passed through the channel of a standard colonoscope (NaviAid Balloon System) [43].

Double balloon enteroscopy — There are three DBE systems available. The standard DBE system includes an endoscope with an 8.5 mm diameter and a 200 cm working length (Fujinon EN-450P5), a 145 cm soft overtube with an outer diameter of 12.2 mm, and a specifically designed pump (picture 1). After the overtube is backloaded onto the scope, a soft latex balloon is attached to the tip of the enteroscope. The balloon can be inflated and deflated using a pump through the air channel in the enteroscope. The flexible overtube also has a latex balloon at its tip that can be inflated and deflated. The pressure in both balloons is monitored and regulated at 5.6 kPa.

A therapeutic double balloon enteroscope (Fujinon EN-450T5) is also available. It is similar to the standard enteroscope with a 200 cm working length, but has a larger outer diameter (9.4 mm) so that it can accommodate a larger channel (2.8 mm in diameter). A shorter double balloon endoscope with a working length of 152 cm is also available (Fujinon EN-450B15). This endoscope will accept both endoscopic retrograde cholangiopancreatography (ERCP) length and colonoscopy length accessories and is primarily used for cases of incomplete colonoscopy and for ERCP in patients with surgically altered anatomy.

Patient preparation and sedation — Patients should fast after midnight the evening prior to the examination to allow time for food residue to clear the small bowel. In addition, patients undergoing retrograde examinations should receive a bowel preparation to cleanse the colon. (See "Bowel preparation before colonoscopy in adults".)

Balloon-assisted enteroscopy can generally be performed under moderate sedation, though some centers prefer to perform anterograde procedures under general anesthesia. One reason for using general anesthesia is that it can be difficult to maintain adequate sedation throughout what is often a prolonged procedure. (See "Gastrointestinal endoscopy in adults: Procedural sedation administered by endoscopists".)

Technique for DBE — DBE can be performed from either the mouth (anterograde approach) or the anus (retrograde approach). The insertion route is chosen according to the estimated location of the suspected lesion(s). In a study of 60 patients undergoing DBE, an anterograde approach was used for lesions noted in the first 60 percent of a capsule endoscopy study (based on the time at which the lesion was noted in the small bowel relative to the total small bowel transit time), whereas a retrograde approach was used for lesions in the distal 40 percent [44]. Using this cutoff, the lesions were reached on the first examination in all patients.

With an antegrade examination, the enteroscope is advanced using repetitive cycles of balloon inflation/deflation and scope advancement (figure 2). During one cycle of the procedure, the scope is advanced until no further forward progress is made. The balloon on the tip of the scope is then inflated, anchoring the small bowel. Once the small bowel is anchored by the enteroscope balloon, the balloon on the overtube is deflated (having been inflated during the prior cycle) and advanced until it reaches the inflated balloon on the scope. The balloon at the end of the overtube is then inflated, and with both balloons inflated, the scope and overtube are gently withdrawn to remove loops and pleat the small bowel onto the overtube. The balloon on the scope is then deflated, and the cycle is repeated until the scope can no longer be advanced or the lesion of interest is reached. The procedure is carried out in reverse during withdrawal of the scope.

The procedure is the same for retrograde examinations, except that the cycles of scope advancement and withdrawal are carried out in the colon, as well as in the small bowel, to ensure that there is no colonic looping prior to intubation of the terminal ileum.

The point of maximal insertion is frequently tattooed so that it can be identified on subsequent capsule endoscopy, deep small bowel enteroscopy from the opposite approach, or at the time of surgery. The maximal insertion depth may be limited in patients with adhesions due to prior surgery or inflammatory disorders.

Fluoroscopy may be used when initially learning balloon-assisted enteroscopy to permit the endoscopist to observe advancement and reduction of the enteroscope and to identify looping (image 1) [3].

Efficacy — The majority of the published data on balloon-assisted enteroscopy are from studies of DBE. Multiple reports have described experience with DBE, and a few have compared it with other methods to visualize the small bowel [25,45-56]. Most of these studies focused on patients with suspected small bowel bleeding. (See "Evaluation of suspected small bowel bleeding (formerly obscure gastrointestinal bleeding)", section on 'Enteroscopy'.)

Reported mean procedure times with DBE range from 73 to 123 minutes, with average small bowel insertion depths of 220 to 360 cm for antegrade examinations and 124 to 183 cm for retrograde examinations [25,51,54,57,58]. In a majority of patients without a significant history of abdominal surgery who undergo an antegrade examination, the mid to distal jejunum or proximal ileum can be reached within 40 to 80 minutes of examination time (not including the time to set up for the examination, which can be significant) [48,58].

Retrograde examinations are more difficult, and even in expert hands, the failure rates for ileal intubation during retrograde examinations range from 7 to 30 percent [54,58-60]. Even if the terminal ileum is intubated, adhesions may limit subsequent advancement to only 10 to 15 cm within the small bowel.

The reported rates of complete enteroscopy (ie, visualization of the entire small bowel, often through a combination of an anterograde and retrograde approach) vary widely. Rates of 70 to 86 percent have been reported in Japan [1,25,61] compared with 4 to 92 percent reported in the United States and Europe [47,57,58,62-64]. Lower rates of complete enteroscopy have been noted in patients who are obese and in operators with less experience with DBE. Typically, complete enteroscopy is accomplished by performing both an antegrade and a retrograde examination.

Diagnostic and therapeutic yields — The diagnostic yield of DBE ranges from 40 to 80 percent, with therapy being performed in 15 to 55 percent of patients [25,51,54,57,58,60]. A meta-analysis of 11 studies that compared DBE with capsule endoscopy estimated that the overall yield for clinically pertinent small bowel findings was similar with the two examinations (60 and 57 percent) [65]. The yield was also similar when comparing specific types of findings such as vascular malformations (picture 2) (24 percent with both), tumors (picture 3) (11 percent with both), polyps (picture 4) (11 percent with both), and inflammatory lesions (18 and 16 percent).

A few studies have compared DBE with push enteroscopy and found better diagnostic yields with DBE [45,46]. The better diagnostic yields with DBE were in part related to higher rates of complete visualization of the small bowel (ie, total enteroscopy).

A study of 2245 DBE examinations in 1765 patients found that the diagnostic yield varied with the indication [63]:

●Peutz-Jeghers syndrome: 82 percent

●Suspected small bowel bleeding: 53 percent

●Crohn disease: 47 percent

●Abdominal pain: 19 percent

●Diarrhea: 16 percent

In patients with small bowel bleeding due to angiodysplasia, DBE allows for effective treatment with argon plasma coagulation (APC), though recurrent bleeding is common [66,67]. In a study of 50 patients with small bowel lesions, 44 patients (88 percent) were treated with APC for angiodysplasia [66]. After a mean follow-up of 55 months, hemoglobin levels increased from a mean of 7.6 g/dL prior to treatment to 11.0 g/dL following treatment. In addition, there was a significant decrease in the number of patients requiring blood transfusions, from 30 patients prior to treatment to 8 patients following treatment. However, small bowel bleeding recurred in 21 of the patients (48 percent) treated with APC.

In a second study that included 98 patients with small bowel vascular lesions who were followed following treatment during DBE (primarily with APC), rebleeding occurred in 45 (46 percent) at 36 months [67]. Factors that increased the risk of bleeding included the total number of observed lesions and the presence of valvular and or arrhythmic cardiac disease.

Learning curve — The technical skill to perform DBE improves with experience. The learning curve for DBE was evaluated in a study involving six tertiary centers in the United States [58]. A total of 188 patients underwent 237 DBE procedures, mainly for suspected small bowel bleeding. Approximately two-thirds of the cases were antegrade. The mean procedure duration for antegrade examinations was 102±45 minutes for the first 10 cases, declining to 90±37 minutes thereafter. The improvement in procedure duration was observed only for anterograde cases, with no change in mean procedure time being observed for retrograde examinations. In addition, retrograde cases failed to reach the small bowel in 31 percent of cases.

It has been estimated that the learning curve for antegrade examinations is approximately 10 cases, compared with 20 to 30 cases for retrograde examinations [3,68]. However, some endoscopists require more than 100 to 150 cases to develop expertise [57].

Complications — The overall complication rates for DBE in large series have ranged from 1.2 to 1.6 percent [63,69,70]. A meta-analysis found that minor complications occurred in 9.1 percent of procedures, whereas major complications were reported in 0.7 percent. Complications include pancreatitis, perforation, bleeding, and aspiration pneumonia [63,69-72]. The rate of complications may be higher for patients undergoing therapeutic procedures compared with those undergoing diagnostic procedures (eg, 4.3 versus 0.8 percent in a series of 2362 procedures) [69].

Pancreatitis — Pancreatitis is the most common significant complication of DBE. The rate of pancreatitis following DBE is approximately 0.3 percent based upon data from three series with a total of 8734 procedures [69,70,72]. The cause of pancreatitis is uncertain, but may be related to physical trauma to the pancreas. It is important to distinguish clinical pancreatitis from hyperamylasemia alone, which occurs in approximately 50 percent of patients, especially following long procedures [73,74]. There are no proven methods to reduce the incidence of pancreatitis.

Perforation — The rate of perforation is 0.1 to 0.4 percent [69,70,72,75]. The cause of perforation is likely to be multifactorial. In one report, perforation occurred in two patients who may have been at increased risk due to inflammation [25]. One had intestinal lymphoma and had received chemotherapy, while the other had Crohn disease. In a second study that included more than 29,000 patients who underwent balloon-assisted enteroscopy, there were 32 perforations (0.1 percent) [75]. Factors associated with an increased risk of perforation included inflammatory bowel disease being treated with glucocorticoids (odds ratio [OR] 8.6) and use of glucocorticoids for other reasons (OR 3.3).  

Therapeutic interventions also increase the risk of perforation. In one series, 3.4 percent of polypectomies were complicated by perforation [70]. The risk is also increased if stricture dilation is carried out in the setting of active ulceration. Balloon dilation in these cases should be postponed until the ulcer has healed [76].

Surgically altered GI anatomy is another risk factor for perforation. In one series, the rate of perforation in 219 examinations in patients with surgically altered anatomy was 3 percent [72]. Patients who may be at particularly increased risk include those with an ileoanal or ileocolonic anastomosis and those having their examination performed through a stoma. This has led some authorities to suggest that altered surgical GI anatomy should be considered a relative contraindication to balloon-assisted enteroscopy. (See 'Contraindications' above.)

Given these risk factors for perforation, we suggest that further insertion of the enteroscope across the lesion be avoided when fragile lesions such as active ulceration are encountered in the small intestine. In addition, DBE should be performed with caution in patients with a history of GI tract surgery.

Bleeding — Bleeding has been reported in approximately 0.2 percent of procedures [70,72]. Polypectomy and biopsy appear to be risk factors for bleeding.

Other — Additional reported complications include two cases of aspiration pneumonia in a series of 265 procedures [71], one cecal volvulus in a series of 2478 procedures [72], and a case report that described severe esophageal trauma from the overtube in a patient with eosinophilic esophagitis, a condition known to predispose to mucosal tearing [77]. (See "Clinical manifestations and diagnosis of eosinophilic esophagitis".)

Single balloon enteroscopy — The SBE system uses a 200 cm high-resolution enteroscope (Olympus SIF-Q180) with a 2.8 mm working channel. The overtube is 140 cm long with a 13.2 mm outer diameter. The overtube is equipped with a silicone balloon at its tip, which can be inflated and deflated with a pressure setting range of -6.0 to + 5.4 kPa.

The technique for SBE is similar to that used for DBE (see 'Technique for DBE' above). Like DBE, SBE uses an overtube with a distal balloon to aid with scope advancement through the small bowel. However, SBE uses the scope's flexible tip to anchor the scope, rather than a second balloon on the tip of the enteroscope as with DBE (figure 3). Anchoring stabilizes the scope, permitting advancement of the overtube. The overtube balloon is then inflated, and the tip of the enteroscope is straightened. With the overtube balloon inflated, the scope and overtube can be withdrawn, pleating the small bowel onto the overtube. The enteroscope is then advanced. Like DBE, the cycle of advancement and withdrawal is repeated until the scope can no longer be advanced or the lesion of interest is reached. As with DBE, the point of maximal insertion is frequently marked with a tattoo.

Experience with SBE suggests that its efficacy is similar to that of DBE. Diagnostic yields have ranged from 41 to 65 percent, and therapeutic yields have ranged from 7 to 50 percent [59,78-86]. Average depths of small bowel insertion range from 133 to 270 cm for antegrade examinations and 73 to 199 cm for retrograde examinations [78,81,83,84,86]. However, the rate of total enteroscopy may be lower than with DBE at 0 to 24 percent [78-80,85]. In our experience, this is largely due to more difficult intubation of the terminal ileum with SBE compared with DBE. With DBE, the balloon on the tip of the enteroscope can anchor the scope in the small bowel while the overtube is advanced. This is not an option with SBE, so it is harder to maintain position of the enteroscope within the small bowel during overtube advancement. (See 'Diagnostic and therapeutic yields' above.)

The majority of the data on complications of balloon-assisted enteroscopy come from studies of DBE. Complications that have been reported with SBE include abdominal pain, fever, pancreatitis (following endoscopic retrograde cholangioscopy), mucosal tears, and perforation [59,78-81,84,87,88]. (See 'Complications' above.)

SPIRAL ENTEROSCOPY — Spiral enteroscopy is an alternative to balloon-assisted enteroscopy for antegrade evaluation of the small bowel. The method was developed in an attempt to provide a simpler, faster method for deep small bowel enteroscopy. Spiral enteroscopy uses an overtube with a soft raised helix at its distal end (Endo-Ease Discovery SB) (picture 5).

Like balloon-assisted enteroscopy, spiral enteroscopy can be performed using moderate sedation or general anesthesia. However, if the patient is endotracheally intubated, the anesthesiologist should be asked to deflate the cuff on the endotracheal tube until the spiral is completely within the stomach to prevent esophageal trauma that may be induced by the raised helical spirals on the overtube. (See "Gastrointestinal endoscopy in adults: Procedural sedation administered by endoscopists".)

The 118-cm overtube is compatible with enteroscopes that are 200 cm long and between 9.1 and 9.5 mm in diameter (ie, the enteroscopes used for double balloon or single balloon enteroscopy, but not standard enteroscopes). The spirals on the overtube are either 4.5 mm (low profile) or 5.5 mm (standard profile) high. The overtube has a coupling device that affixes it to the scope, while permitting rotation of the overtube. By rotating the overtube clockwise, the small bowel is pleated onto the overtube, and the enteroscope is advanced.

Data on spiral enteroscopy are limited. Initial reports suggest decreased procedure times and similar depths of insertion compared with balloon-assisted enteroscopy and low complication rates [84,89-94]. However, other reports suggest lower rates of complete small bowel enteroscopy with spiral enteroscopy compared with balloon-assisted enteroscopy. This, however, is not surprising since spiral enteroscopy is performed from an antegrade approach, whereas balloon-assisted enteroscopy can be performed both antegrade and retrograde, increasing the chances for complete enteroscopy. In one study, the rate of complete small bowel enteroscopy was much lower for spiral enteroscopy compared with balloon-assisted enteroscopy (8 versus 92 percent), though the rate of complete small bowel enteroscopy with balloon-assisted enteroscopy was higher than that reported in many studies [64]. (See 'Efficacy' above.)

In addition, the reported yield of spiral enteroscopy in some studies has been lower than that seen with balloon-assisted enteroscopy and varies by indication.

●In a study of 27 patients with suspected small bowel bleeding, 25 underwent spiral enteroscopy [89]. The examination could not be carried out in two patients (due to a Schatzki ring or an inability to advance the overtube into the esophagus). The depth of insertion ranged from 80 to 340 cm from the ligament of Treitz (mean 175 cm), and the procedure time ranged from 19 to 65 minutes (mean 37 minutes). Possible sources of bleeding were noted in nine patients (33 percent), including angiodysplasia in eight and a duodenal ulcer in one. All of the angiodysplasias were treated with bipolar cautery. There were no major complications. Superficial esophageal mucosal trauma was noted in 22 percent of patients, and a postprocedure sore throat was noted in 28 percent.

●In a second report, 90 procedures were carried out in 95 patients [90]. The most common indications for the procedure were abdominal pain with loose stools or diarrhea (72 percent), occult GI bleeding (12 percent), overt gastrointestinal (GI) bleeding (3 percent), a history of intestinal polyps (11 percent), and chronic abdominal pain alone (3 percent). In five of the patients, the overtube did not successfully engage the small bowel. The mean procedure time was 34±8 minutes, and the mean depth of insertion was 262±57 cm. Notable findings were present in 12 percent of the patients. There were no perforations and only two cases of deep mucosal tears associated with the procedure.

●In a third series of 61 patients, the procedure was successfully completed in 56 patients (92 percent). The most common indication was GI bleeding (85 percent). The average depth of insertion was 217±79 cm, and the mean procedure time was 41±15 minutes [91]. Positive findings were present in 36 patients (59 percent), and therapeutic maneuvers were carried out in 30 patients (49 percent). Complications included bradycardia requiring procedure termination (one patient), mucosal abrasions in the esophagus (2 patients), and abdominal pain necessitating hospital admission.

●A low rate of complications was reported in a series of 1750 cases [93]. Severe complications were reported in seven procedures (0.4 percent). Six of the complications were perforations, and all occurred as the enteroscope was being pushed through the overtube. Three of the perforations occurred with clinicians who had performed fewer than 10 cases [93].

The yield of spiral enteroscopy in patients with positive findings on capsule endoscopy has also been examined. One study included 56 spiral enteroscopy procedures [95]. Findings on capsule endoscopy included angiodysplasia (26 patients), masses (eight patients), ulcers (four patients), polyps (four patients), abnormal mucosa (six patients), fresh blood (six patients), and stricture (one patient). The findings on capsule endoscopy were reproduced with spiral enteroscopy in 30 patients (54 percent). The type of finding on capsule endoscopy was associated with reproducibility on spiral enteroscopy. Blood was reproducible in 86 percent of patients, angiodysplasia in 69 percent, abnormal mucosa in 50 percent, masses in 38 percent, polyps in 33 percent, and ulcers and strictures in zero percent.

SUMMARY AND RECOMMENDATIONS

●Deep small bowel enteroscopy permits visualization and interventional therapy throughout the small bowel. Available options for deep small bowel enteroscopy include double balloon enteroscopy (DBE), single balloon enteroscopy (SBE), and spiral enteroscopy. (See 'Introduction' above.)

●Balloon-assisted enteroscopy (ie, DBE and SBE) can be performed orally or per rectum, whereas spiral enteroscopy can only be performed orally. (See 'Balloon-assisted enteroscopy' above and 'Spiral enteroscopy' above.)

●The most common indication for deep small bowel enteroscopy is the evaluation of suspected small bowel bleeding. There are multiple other indications, including the evaluation of suspected small bowel malignancies and the evaluation of small bowel Crohn disease. (See 'Diagnostic applications' above.)

●Therapeutic applications for deep small bowel enteroscopy include the treatment of gastrointestinal bleeding from the small bowel, small bowel polypectomy, and small bowel stricture dilation. (See 'Therapeutic applications' above.)

●We suggest that deep small bowel enteroscopy (rather than wireless capsule endoscopy, push enteroscopy, or intraoperative enteroscopy) be used when (Grade 2C) (see 'Indications' above):

•There are findings on wireless capsule endoscopy or radiographic small bowel imaging that require biopsy or therapeutic intervention, including active bleeding from the small bowel that is out of reach of a standard endoscope.

•There is suspicion for a small bowel lesion despite a negative capsule study.

•There is suspicion of impaction of a video capsule proximal to a small bowel stricture.

●Deep small bowel enteroscopy is generally well tolerated, but has been associated with many of the complications seen with other forms of endoscopy. The two most common serious complications are perforation and pancreatitis. (See 'Complications' above and 'Single balloon enteroscopy' above and 'Spiral enteroscopy' above.)