Development of the first capsule (Fig. 1) was based on three scientific advances: a CMOS (complementary metal oxide silicone) microchip capable of producing an image comparable with that obtained with a CCD camera; an ASIC (application-specific integrated circuit) system, which allows integration of a small, low-energy video transmitter; and miniature high-power lighting such as an LED (light-emitting diode). These three components are placed in a capsule measuring 1.1 cm × 2.6 cm that can be swallowed. The field of vision obtained is 140°. It is weighted so that it retains its longitudinal orientation for approximately 80% of its intestinal journey, and it passes through the body naturally. The system also comprises a series of sensors which are placed on the surface of the patient’s abdomen and detect signals emitted by the capsule. These are transmitted to a high-frequency tape recorder, contained in a case and worn on a belt by the patient, before transfer to a workstation. The capsule is eliminated in the stools and is a single-use device. This description corresponds to the system developed by Given Imaging Ltd. Since then, the capsule has been improved and is available under the name ‘PillCam SB’, characterized by a wider angle of vision (156°), better resolution (65 536 pixels), and an increased depth of field. The ‘EndoCapsule’, ‘MiRoCam’ and ‘OMOM’ capsules differ in using a CCD rather than CMOS sensor (Fig. 2) to capture images. Studies comparing the ‘Pillcam’ and ‘Endoscapsule’ have not demonstrated any differences in diagnostic yield in patients with obscure gastrointestinal bleeding. The ‘MiroCam’ capsule (Fig. 3) has longer-life batteries (11 h), is smaller in size (11 × 24 mm), has a larger number of pixels (102,400), takes three images per second, and transmits data using conduction through body tissues. This requires constant contact with the mucosa, which may be a limiting factor. Comparative studies with the other two systems are currently underway. The ‘OMOM’ capsule (27.9 mm long, 13 mm diameter, and 6 g weight) is significantly bigger than the others (24–26 × 11 mm and 3.4–3.6 g weight).

Figure 1 Development of the Given Imaging system.

(Courtesy of Given Imaging Ltd.)

Figure 2 Olympus Endo-cap system: antennae and case.

(Courtesy of Olympus.)

Figure 3 Intromedic MiroCam system.

(Courtesy of IntroMedic.)

2 Examination procedure

The patient fasts for 12 h before swallowing the capsule. The five 1.2 V nickel batteries are worn by the patient on a belt, along with the 305 GB data recorder for storing the images. The patient may move around freely after swallowing the capsule. It is eliminated in stools in 24–48 h, depending on gut transit. Air bubbles and food residue may impair image quality and in fit patients, bowel preparation is recommended, as it improves mucosal visualization and diagnostic yield. Polyethylene glycol (PEG) solutions or sodium picosulphate can be used. There is some evidence that simethicone reduces air bubbles and improves views. Transit of the VCE capsule may be slower in diabetic patients or those in poor health and, for them, a prokinetic such as erythromycin is recommended.

3 Safety of VCE and contraindications

No harmful effects have been reported in cases of prolonged capsule retention. The presence of a capsule for 2 years in one individual had no adverse consequences. There is, however, a real risk of small intestinal obstruction as a result of stricturing, especially in inflammatory disorders. This risk is approximately 3.6% in large-scale studies and is offset by the fact that capsule retention is often caused by the lesion or lesions requiring examination by VCE in the first place. Surgery with or without endoscopy usually resolves both the problem of retention and the underlying disease at the same time.

To solve the problem of retention, Given Imaging Ltd has developed a calibration capsule, called the ‘M2A Patency Capsule’. If it has not been expelled after 2–3 days, this breaks down spontaneously into small fragments, which easily pass through a narrowed segment. Latest modifications have incorporated two openings at each end of the capsule (the Agile Patency Capsule, Fig. 4), to enhance capsule breakdown. It is important to remember that neither small intestine barium studies nor CT or MR enteroclysis can detect all strictures. It is therefore essential to enquire about the patient’s medical history (complex surgery, use of NSAIDs, radiotherapy of the abdomen, and recent episodes of obstructive symptoms) before carrying out an examination by VCE. The risk of obstruction should be explained clearly before VCE, along with the possibility that a retained capsule may have to be removed endoscopically or surgically. CT or MR enteroclysis or the use of an Agile Patency Capsule is recommended before performing VCE in patients felt to be at risk of small bowel strictures.

Figure 4 Agile patency capsule.

(Courtesy of Given Imaging Ltd.)

Clinical Tip

VCE should be performed with caution in patients at high risk of, or suspected of having, intestinal strictures or obstruction. If VCE is undertaken, a patency capsule study or small bowel imaging should be performed first.

Warning!

VCE is not approved for use in pregnant women because of the microwaves emitted. It is contraindicated in patients with swallowing disorders or signs of gastrointestinal obstruction. VCE does not interfere with cardiac pacemaker function. MRI studies should not be undertaken until it is clear that the capsule has been expelled.

4 Indications and results

VCE has already changed the management of patients in the following disorders:

4.1 Chronic obscure gastrointestinal bleeding

This is defined as isolated or recurrent melena, rectal bleeding or iron deficiency anemia with evidence of gastrointestinal bleeding. Patients should have undergone negative upper endoscopy and total colonoscopy before VCE is considered. A positive diagnosis may be found in 55–81% of patients, the yield being higher in those with overt as opposed to obscure bleeding. VCE is superior in detecting lesions responsible for bleeding compared with push enteroscopy (PE), particularly in patients with overt bleeding. Studies have also emphasized the need for examination by VCE as soon as possible after the bleeding episode, the diagnostic yield dropping as time elapses. Finally, the use of a repeat study in patients in whom VCE had initially been negative will yield a diagnosis in a significant number of patients. Two meta-analyses of 14 and 17 studies, respectively, demonstrate that VCE yields a positive diagnosis in 63% of patients compared with 28% for push-enteroscopy. The lesions detected are usually, in decreasing frequency, arteriovenous malformations (Fig. 5), ulceration secondary to NSAIDs, and tumors. When compared with double balloon enteroscopy (DBE), both methods have similar diagnostic yields in obscure gastrointestinal bleeding: 43–60% for DBE and 59–80% for VCE.

Figure 5 (A,B) Arteriovenous malformation.

4.2 Recurrent iron deficiency anemia

VCE is associated with a diagnostic yield of approximately 50–60% of patients with a negative upper and lower gastrointestinal work-up and is superior to small bowel radiology.

4.3 Crohn’s disease

VCE detects more intestinal lesions in patients with Crohn’s disease (Fig. 6) than conventional radiological imaging. The lesions usually detected are mucosal: erosions, purpuric lesions, ulceration, aphthoid lesions, and strictures. Some practical conclusions are shown in Box 1.

Figure 6 Crohn’s disease of the small intestine. (A) Stenosis. (B) Ulcer.

Box 1 The role of VCE in Crohn’s disease

• VCE is not indicated for diagnosis in patients with Crohn’s confirmed by other radiological or endoscopic investigations.

• VCE is useful if Crohn’s disease is suspected clinically or from laboratory tests or during recurrence if the radiological and endoscopic picture is normal.

• VCE is useful in patients with indeterminate colitis to detect small intestinal lesions.

• Detection of jejunal ulcerative lesions may predict early recurrence in a patient who has undergone ileocecal resection.

One of the problems in evaluating VCE in Crohn’s disease is the lack of reliable objective criteria for diagnosis. Scoring indices are under evaluation, based on three parameters: edematous appearance of villi, the presence of ulcers and the presence of strictures. Although these scores provide a common language to try and quantify the disease activity in the small intestine, they need further validation. Ulcers in the small bowel are not always due to Crohn’s – NSAIDs, lymphoma, radiation, and vasculitis can all cause similar appearances. The risk of capsule retention in CD patients is 5–13% and so small bowel imaging or patency capsule studies should be performed to exclude strictures before VCE is undertaken.

4.4 Celiac disease

Some authors have suggested that VCE could be an alternative to endoscopic duodenal biopsies obtained at OGD, particularly in patients unwilling to undergo the procedure, and could be carried out for: chronic iron-deficiency anemia, children with clinical evidence and laboratory results suggesting celiac disease, patients with anti-transglutaminase antibodies, and atypical symptoms in elderly patients (Fig. 7A,B).

Figure 7 (A,B) Celiac disease. (C) Enteropathy associated T-cell lymphoma (EATL) complicating celiac disease.

VCE in combination with DBE is, moreover, the best way of examining patients with celiac disease who have warning symptoms (weight loss, anemia and abdominal pain), while adhering closely a gluten-free diet. VCE is a useful tool for monitoring patients with celiac disease to detect malignant lesions, i.e. adenocarcinoma or lymphoma (Fig. 7C), particularly if ulcerative jejunitis is present.

4.5 NSAID enteropathy

Ulcers, erosions and stenotic diaphragms or webs are usually found (Fig. 8). The clinical significance of minor lesions accompanying the use of NSAIDs is uncertain, as they are also detected in up to 22% of healthy volunteers participating in the control group in studies of NSAID toxicity.

Figure 8 NSAID toxicity.

4.6 Detection of intestinal tumors

The frequency of these tumors (Fig. 9) in patients examined by VCE for chronic obscure gastrointestinal bleeding is approximately 6–12%, and 60% of these are malignant. Since the introduction of VCE, it has been noted that the most frequent presentation of these intestinal tumors is chronic obscure bleeding rather than abdominal pain, weight loss or obstruction. This means that VCE has the potential to detect these tumors at an earlier stage.

Figure 9 (A) Adenocarcinoma of the small intestine. (B) Carcinoid tumor. (C) Gastrointestinal stromal tumor (GIST). (D) Lipoma.

4.7 Surveillance of familial polyposis

VCE is capable of demonstrating the existence of polyposis (Fig. 10) along the small intestine. Although it may miss duodenal lesions in comparison with PE and DBE, it performs better in the jejunum and ileum. Its use is even more impressive in Peutz–Jeghers syndrome in which it can detect lesions capable of causing intussusception, and demonstrate ulcerated polyps responsible for chronic anemia. Its use is now widely accepted in the surveillance of familial adenomatous polyposis (FAP) associated with duodenal polyps. The same applies in juvenile polyposis. If VCE is used to monitor patients with FAP, it should be kept in mind that it does not detect all lesions in the duodenum, particularly the periampullary region. The duodenum must be investigated by a side-viewing endoscope in these patients. Finally, VCE cannot accurately assess the size of tumors in patients with familial polyposis, and often overestimates this. MR-enteroclysis appears to be better for assessing the size of these lesions.

Figure 10 (A) Peutz–Jeghers syndrome with ulceration. (B) Familial adenomatous polyposis.

Box 2 summarizes the role of VCE in small intestinal disorders.

5 Specific situations

5.1 Children

VCE may be used in children over the age of 9 years. It is specifically indicated in this age group for the diagnosis of chronic anemia, and can detect ulcerated or intussuscepting polyps in Peutz–Jeghers syndrome. It is also useful in the diagnosis of Crohn’s disease when it is suspected from the clinical presentation.

5.2 Other situations

In diabetic patients with gastroparesis, a capsule can be placed in the stomach using an enteroscope overtube or in the duodenum using a device that releases the capsule mechanically. Esophageal VCE (Pillcam ESO, Given) is available and may be useful in screening patients for Barrett’s esophagus or esophageal varices but its role has not yet become established. A colon capsule (PillCam Colon, Given) is under evaluation at present.

6 Technical aids to reading images obtained by VCE

Precise anatomic localization of the capsule (Figs. 12, 13) remains too inaccurate to be used in practice, regardless of the electronic means of detection used. The capsule is, in fact, located based on differentiation between the appearance of the jejunum and the ileum and the time elapsed in relation to passage through the pylorus and the caecum. The Real-Time Viewer, which is available from Olympus, Given Imaging Ltd and MiroCam, allows the images observed by the capsule to be read directly in real-time. These three systems are similar in principle and can be used at the patient’s bedside. It is useful for determining whether the capsule has passed through the pylorus and for deciding to administer an erythromycin infusion to make sure the small intestinal examination is completed within the battery’s life. It may be particularly useful for locating the site of active gastrointestinal bleeding, thereby allowing targeted therapeutic endoscopy.

Figure 12 Location system.

(Courtesy of Given Imaging Ltd.)

Figure 13 Red detection system.

(Courtesy of Given Imaging Ltd.)

7 Discussion

VCE has had a major impact on the examination of the small intestine in recent years. It is superior to other radiological examinations in the detection of mucosal, and particularly vascular, lesions. The same applies to tumors, particularly those measuring <1 cm. Its limitations relate to inferior image quality than classic endoscopy and to its inability to be manipulated in order to examine the small intestine more completely, or to be stopped over a suspicious lesion. Inability to take biopsies is another limitation at present.

Furthermore, the combined use of VCE and DBE to examine the small intestine has radically transformed the investigation and treatment of diseases of the small intestine. Strategies can be developed by combining the initial use of VCE followed by DBE. VCE is capable of indicating the route of insertion (oral or anal), which should then be carried out at DBE, thus allowing the correct management of patients. DBE should, nevertheless, still be considered the examination of choice if intestinal stricturing is strongly suspected or there is severe active bleeding known to be of intestinal origin.

8 Recent developments in VCE: esophagus and colon

8.1 The esophagus (Fig. 14)

A new VCE method has been developed by Given Imaging Ltd (PillCam™ ESO) for detecting esophageal mucosal abnormalities. It is a double-domed capsule which produces seven images per second at each end. The patient fasts for 2 h before the examination and the transit of the PillCam ESO is slowed after the patient swallows the device while lying down and then gets up gradually from this position over a period of 7 min. The images of the esophageal mucosa obtained with this capsule are comparable with those obtained at OGD. The reading time varies from 5–15 min. A recent modification allows a string to be attached to the capsule, which can then be withdrawn back up the esophagus in a controlled manner with better imaging results.

Figure 14 (A) Esophageal capsule. (B) LA-grade A esophagitis. (C) Esophageal varices grade II.

The sensitivity of VCE is between 60% and 100% for the detection of Barrett’s esophagus and 50–89% for the detection of different grades of esophagitis. Matters are simpler as regards detection of esophageal varices. VCE has a sensitivity of 100% and a specificity of 80% for detecting esophageal varices. There is, moreover, a good correlation between the lesions detected during VCE and OGD for estimating variceal size, although small varices are more difficult to assess. Esophageal VCE may therefore be useful for detecting and monitoring portal hypertension in patients with cirrhosis, and it could replace OGD as the first-line investigation for this. VCE is not appropriate as the first-line endoscopic examination in the investigation of the upper gastrointestinal tract in symptomatic patients.

8.2 The colon

This is a recent development proposed by Given Imaging Ltd. The PillCam Colon (Fig. 15) is a capsule measuring 11 mm by 32 mm with two domes and two cameras. Images are acquired at a rate of 4/s. The batteries have a life of approximately 10 h. This capsule first examines the esophagus, stomach and duodenum, then switches off. It is programmed to switch on again when it reaches the terminal ileum. Patients require intensive preparation before the introduction of the colon capsule since exquisite cleanliness is required for a complete and careful examination of the mucosa, and passage of the capsule must also be facilitated. Stimulant agents (sodium phosphate) and laxatives (bisacodyl) are therefore used. This type of preparation, which is therefore slightly harsher than typical colonic preparation, can be used to obtain a clean colon.

Figure 15 (A) Colon VCE. (B) Ileocecal valve. (C) Transverse colon. (D) Colonic polyp.

One of the main potential indications for the use of this colon video capsule is the detection of colorectal cancer. Two studies show good correlation for the detection of colon polyps between the colon capsule and colonoscopy. Sensitivity and specificity of 56% and 76% for the colon capsule increase to 69% and 100%, respectively if the recording tapes for colon VCE are reviewed by an expert panel.

The difficulties encountered in our personal experience when reading colon VCE recordings are: difficulty detecting polyps owing to fluid in the colonic lumen; too rapid progression of the capsule in some colonic segments, particularly the rectum, and difficulty localizing and measuring the size of lesions found. Other indications are currently being considered for the colon capsule, particularly in patients in whom colonoscopy is incomplete and in monitoring patients at high risk of colorectal cancer, for example those with ulcerative colitis.

Conclusion

VCE is a now a key method of gastrointestinal investigation. It is constantly improving in terms of illumination, angle of view, and resolution. Numerous studies have confirmed its value in the examination of the small intestine, in which it has revolutionized the diagnostic approach. Its role in esophageal and colonic disorders remains to be determined.

Introduction

Enteroscopy is the endoscopic examination of the small intestinal mucosa. Endoscopic investigation of the small bowel has been dominated for the last 20 years by push enteroscopy, which has many diagnostic and therapeutic capabilities but is limited in its depth of insertion. Recent advances in overtube-assisted enteroscopy, with the development of the double balloon enteroscopy (DBE) (Fuji Photo Optical Co, Ltd, Saitama, Japan), single balloon (SBE) (Olympus Ltd, Tokyo, Japan) and spiral enteroscopy (Spirus Medical, Inc, Stoughton, MA, USA) systems, allow much greater depth of insertion than previously possible with push enteroscopy. If retrograde enteroscopy is performed in addition to anterograde enteroscopy, total enteroscopy is possible, allowing visualization of the entire small bowel.

Box 1 Overtube-assisted enteroscopy

• Overtube-assisted enteroscopy is when an enteroscope is used with an overtube.

• There are currently three types of overtube-assisted enteroscopy systems available: DBE, SBE, and spiral enteroscopy.

• Anterograde enteroscopy is where the enteroscope and overtube are advanced through the mouth and into the small bowel.

• Retrograde enteroscopy is where the enteroscope and overtube are advanced through the colon, with intubation of the terminal ileum, and then advancement into the small bowel.

• Total enteroscopy is where the entire small bowel is visualized. This is sometimes possible with anterograde DBE, but is rarely achieved with either SBE or spiral enteroscopy. The combination of anterograde and retrograde enteroscopy allows total enteroscopy in many cases.

DBE, SBE or spiral enteroscopy?

DBE is the most established technique, with the greatest evidence in the literature supporting its use. One study has shown increased depth of insertion of with DBE compared with SBE. The diagnostic accuracy of DBE and SBE have been compared in a prospective study by May et al (2010), in 100 patients with suspected small intestine pathology. Total enteroscopy was achieved in 66% of the patients undergoing DBE and 22% of the patients undergoing SBE (p < 0.001). A total of 72% of the patients who underwent DBE had a significant diagnostic finding or therapeutic intervention compared with 48% in the SBE group (p = 0.025). Based on the results of this study, DBE should be considered the gold standard for investigation of the small bowel. Initial studies of spiral enteroscopy have not altered this position.

Side-effect profiles appear to be similar, although data are limited for SBE and spiral enteroscopy. SBE can be performed by a single endoscopist, while spiral enteroscopy requires two endoscopists. DBE requires two endoscopists when initially learning the technique; however, with experience, particularly with the oral approach, a single endoscopist and trained nurse are sufficient. Both DBE and SBE can be used for both anterograde and retrograde enteroscopy. A colonic spiral enteroscopy overtube has been developed but experience with it is limited.

1 Indications and contraindications

Indications for enteroscopy:

• Assessment of abnormality detected on cross-sectional imaging, contrast studies or capsule endoscopy.

• Assessment of obscure GI bleeding or iron deficiency anemia.

• Assessment of chronic diarrhea.

• Diagnosis and assessment of Crohn’s disease.

• Diagnosis and treatment of small bowel strictures (dilation or stenting).

• Diagnosis and treatment of small bowel polyps, tumor or lymphoma.

• Miniprobes can be placed through the enteroscope to assess submucosal lesions.

• Assessment of refractory celiac disease.

• Assessment of the afferent limb and excluded stomach in patients with altered anatomy (Roux-en-Y), including placement of PEG (Fig. 1).

• ERCP in patients with altered anatomy (Fig. 2) (see Ch. 10.6 for further details).

• Removal of retained foreign bodies.

• Colonoscopy in patients in whom convention colonoscopy has failed.

Figure 1 Radiological image of DBE in the bypassed gastric pouch.

Figure 2 (A) Small intestine anastomosis (Roux-en-Y, bariatric surgery). (B) Dilation of a hepaticojejunal anastomosis. (C) Radiological image of the dilation of the hepaticojejunal anastomosis. (DBE Fujinon.)

Clinical Tip

Performing altered anatomy ERCP

Regular ERCP accessories can be used with the DBE colonoscope (Fujinon EC-540 B15), which has a working length of 152 cm.

Contraindications to overtube-assisted enteroscopy:

• Contraindications are the same as those of endoscopy of the upper and lower digestive tract.

• Retrograde enteroscopy in patients with ileoanal anastomoses is a relative contraindication.

Box 2 Overtube-assisted enteroscopy, VCE or cross-sectional imaging as a first test?

Obscure GI bleeding

Video capsule endoscopy (VCE) should be used as the initial diagnostic test. DBE should be the initial test if an abnormality has already been detected (i.e. CT or MRI) or a therapeutic intervention is required. It should also be used first if a lesion of the small intestine is strongly suspected or in a patient with active bleeding known to originate in the small intestine, particularly if an ileal location is suspected.

Suspected small tumor (<1 cm)

• DBE combined with VCE is superior to radiological techniques for identifying tumors <1 cm.

Larger tumor (>1 cm)

Cross-sectional imaging is useful for identifying tumors >1 cm, and provides information about the lesion and its environment. Overtube-assisted enteroscopy is used to confirm a histological diagnosis or perform a therapeutic intervention.

Inflammatory diseases

Cross-sectional imaging provides information on the wall, determines the topography of lesions and provides information on the surrounding tissues, e.g. fat-wrapping, and even on the degree of inflammation (functional MRI). VCE is useful in this type of disease for locating very small ulcers which cannot be detected by cross-sectional imaging. Overtube-assisted enteroscopy allows histological confirmation or therapeutic intervention.

2 General enterosocpy technique

• Overtube-assisted enteroscopy can be performed using conscious sedation, monitored anesthesia care (MAC) with propofol or general anesthesia.

• An anterograde procedure to the proximal ileum takes approximately 1 h. Retrograde examination to the mid-ileum may take up to 1.5 h. If a long anterograde procedure is envisioned, intubation may be necessary.

• Fluoroscopy is useful when learning any of the overtube-assisted enteroscopy techniques. As endoscopists gain experience with a technique, fluoroscopy requirements decrease.

• Use of CO₂ instead of air, may allow deeper insertion and decreases post-procedure pain.

Clinical Tip

Anterograde or retrograde approach?

If the transit time from ingestion of a capsule at VCE to arrival at the lesion is ≥75% of the total time from ingestion to arrival at the cecum, a retrograde approach should be performed.

3 Double balloon enteroscopy

3.1 Principles

DBE was initially developed by Yamamoto, based on the principle of gathering the small intestine on the enteroscope overtube. The endoscope and the overtube are equipped with latex balloons at their distal end, which are alternately inflated and deflated. By withdrawing the enteroscope and the overtube with their balloons inflated, the small intestine can be pleated onto the overtube. It is possible to reach the jejunum and proximal ileum by an oral approach. Total enteroscopy can be performed by performing retrograde enteroscopy (via the colon), which allows visualization of the distal ileum.

Clinical Tip

How do you know if total enteroscopy has been performed?

• The most distal extent of an anterograde procedure is marked with a tattoo.

• A retrograde procedure is then performed. Once the tattoo is reached, a total enteroscopy has been performed.

3.2 Equipment

The DBE (see Table 1) consists of a thin endoscope 8.5 mm in diameter and 2300 mm long, with a flexible overtube measuring 1450 mm with an external diameter of 12.2 mm. The two latex balloons attach to the end of the overtube and the endoscope, respectively, and are inflated and deflated by a pump, which maintains constant pressure in the balloons (Fig. 3).

Table 1 Specification of enteroscopes and overtubes used for DBE and SBE

Figure 3 (A) Processor and peristaltic pump, Fujinon. (B) Fujinon therapeutic enteroscope. (C) Fujinon enteroscopes with balloons inflated.

3.3 Technique (Fig. 4)

DBE is performed with two endoscopists (at least one of whom is experienced). Anterograde (Fig. 5) and retrograde (Fig. 6) approaches are usually required to visualize the entire small bowel.

Figure 4 (A) Radiological image of DBE by the oral approach. (B) Radiological image of DBE by the anal approach. (DBE Fujinon.)

Figure 5 Anterograde double balloon enteroscopy.

Figure 6 Retrograde double balloon enteroscopy.

Regardless of the route chosen, pleating of the small bowel over the overtube is obtained by the combined withdrawal of the enteroscope and the overtube repeatedly. A total of 12 maneuvers are generally performed in succession, resulting in a significant shortening of the small intestine. The successive withdrawal of the enteroscope and the overtube results in the endoscope being inserted deep into the small intestine. The anal approach is more difficult than the oral approach. Problems may arise as a result of a very long sigmoid colon which requires reduction of loops. Intubation of the ileocecal valve can also be tricky, and requires careful positioning of the endoscope and overtube in the area of the cecum to avoid being too perpendicular to the ileocecal valve.

Anterograde DBE enteroscopy is performed as follows:

The enteroscope is advanced using the following series of maneuvers (Fig. 5). The enteroscope is advanced. The scope balloon is inflated. The overtube is advanced. The overtube balloon is inflated. A ‘short endoscope’ position is achieved by pulling back on the endoscope and overtube together. The scope balloon is then deflated and the enteroscope advanced. The process is then repeated.

Retrograde DBE enteroscopy is performed as follows:

The enteroscope is advanced using a series of maneuvers similar to those described above. The enteroscope is inserted as far as the descending colon (Fig. 6). The scope balloon is inflated. The overtube is advanced and the overtube balloon inflated. The enteroscope and overtube are withdrawn, straightening the sigmoid colon. The enteroscope is then advanced by repeating these maneuvers.

Clinical Tip

Increasing the depth of insertion

• Ensure the overtube remains filled with water to reduce friction.

• Minimize use of air/CO₂.

• Abdominal compression in the center or left lower quadrant.

• Patients can be placed prone, using their weight to provide abdominal compression.

• In retrograde procedure, placing the patient on their back can assist intubation of the ileocecal valve.

3.4 Complications of DBE

The complication rate related to therapeutic intervention with DBE is approximately 3–4%, comprising mainly instances of perforation and bleeding. Although this rate appears slightly higher than for endoscopic procedures, it must be acknowledged that the small bowel is a more difficult area for endoscopic therapy because the lesions are often large (i.e. polyps associated with Peutz–Jeghers syndrome), and the manipulation of accessories is less straightforward. Perforation rates of up to 10% have been reported in specific situations.

The risk of complications, in particular perforation, is higher in patients with altered anatomy (i.e. Roux-en-Y).

3.5 Results of DBE

The first results were published by Yamamoto. An initial retrospective study of 178 enteroscopy procedures, including 89 anterograde and 89 retrograde procedures, performed in 123 patients, 66 of whom had obscure gastrointestinal bleeding. Total examination of the small intestine by the oral approach was possible in two patients. In 22 patients, a combination of the two approaches achieved examination of the whole small intestine. The lesions found included angiodysplasia, ulcers related to the use of NSAID or secondary to Crohn’s disease, polyps, and tumors. The source of the bleeding was identified in 50 of the 66 patients who had been referred for obscure digestive bleeding. DBE was never preceded by VCE in this study.

Three European studies confirmed these initial results. DBE allowed treatment in 62% of the 100 patients examined, of whom 42% had APC, polypectomy or dilation. Medical treatment was implemented as a result of DBE in 12% of cases and the patient was referred for surgery in 8% of cases.

3.6 Obscure GI bleeding

The diagnostic superiority of DBE over push enteroscopy in obscure digestive bleeding was demonstrated in a series of 52 patients with obscure GI bleeding in whom anterograde DBE found lesions in 38 patients, compared with 23 patients who underwent push enteroscopy (Fig. 7).

Figure 7 (A) AVM of the small intestine. (B) Treatment with APC of an AVM of the small intestine. (DBE Fujinon.)

3.7 Crohn’s disease

DBE is the method of choice for obtaining endoscopic and histological confirmation of Crohn’s disease affecting the small intestine (Fig. 8A,B). DBE should be performed only if it alters patient management either by assessing the severity of mucosal lesions and their extent, or to determine whether they are fibrostenotic or inflammatory in nature. DBE should be used if a short fibrous stenotic stricture requires dilation. DBE should never be performed in active Crohn’s disease (Fig. 8C). Some 50% of dilated patients retain the benefit of this endoscopic procedure at 6 months.

Figure 8 (A) Crohn’s disease, with stricture. (B) Crohn’s disease with pseudo polyps. (C) Dilation of a stricture in Crohn’s disease. (DBE Fujinon.)

3.8 Tumors

DBE and VCE are comparable for detecting tumors. DBE is useful for the detection and removal of polyps in both familial adenomatous polyposis (FAP) and Peutz–Jeghers syndrome (PJS) (Fig. 9A). DBE should be used as the first procedure if polypectomy is envisaged. Use caution when performing polypectomies in this group of patients, particularly for large polyps or those with a broad stalk (Fig. 9B). Submucosal injection with dilute adrenaline (epinephrine) should be used to decrease the risk of bleeding or perforation.

Figure 9 (A) A polyp in a patient with Peutz–Jeghers syndrome. (B) Pediculated polyp of small intestine. (DBE Fujinon.)

Clinical Tip

How do you know what distance the enteroscope has been inserted?

Several techniques have been proposed including:

• Adding the centimeters of scope inserted during each cycle of passage and using this number to estimate the total depth of insertion

• Measuring the distance during the withdrawal phase of the procedure

• Fluoroscopy has been used to assess the depth of insertion, assuming that the left upper quadrant correlates with the proximal jejunum, the left lower quadrant with the proximal ileum, the pelvis with the mid-ileum and the right lower abdomen with the terminal ileum.

4 Single balloon enteroscopy

The single balloon enteroscopy (SBE) system (Fig. 10) was developed by Olympus. It can be used to perform both anterograde and retrograde examinations. Total enteroscopy rates appear to be lower in SBE (15%) compared with DBE (40%). The overtube is coated with silicone and measures 140 cm (ST-SB1 Olympus) with an external diameter of 13 mm (see Table 1). The balloon is made of silicone and is attached to the end of the overtube.

Figure 10 Single balloon enteroscope. (Olympus.)

4.2 Results

The method is relatively easy to perform and allows the same high quality examination of the jejunum as DBE.

4.3 Complications

Lacerations have been described, possibly related to the positioning of the endoscope tip during pulling maneuvers of the overtube with its balloon inflated. Cases of perforation have also been reported.

5 Spiral enteroscopy

The Spirus system (Fig. 11), developed by Endo-Ease Discovery SB (Table 2), is based on a different principle from the previous two systems. The small intestine is concertinaed by rotating the overtube.