Since the introduction of double-balloon enteroscopy 15 years ago, flexible enteroscopy has become an established method in the diagnostic and therapeutic work-up of small bowel disorders. With appropriate patient selection, diagnostic and therapeutic yields of 70% to 85% can be expected. The complication rates with diagnostic and therapeutic DBE are estimated at approximately 1% and 3% to 4%, respectively. Appropriate patient selection and device selection, as well as skill, are the key issues for successful enteroscopy. However, technical developments and improvements mean that carrying out enteroscopy is likely to become easier.
Key points
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Double-balloon enteroscopy (DBE) was the first flexible technique for achieving deep small bowel endoscopy without the need for surgery.
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Proper patient selection and device selection are mandatory for successful diagnosis and treatment.
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Skill in enteroscopy and in the management of small bowel diseases is the key to successful enteroscopy.
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DBE provides the highest rate of complete enteroscopy if complete enteroscopy is needed.
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Obscure bleeding should no longer be used as a synonym for small bowel bleeding, but should be limited to gastrointestinal bleeding of unclear origin after a negative diagnostic work-up including enteroscopy.
Introduction
Since the introduction of double-balloon enteroscopy (DBE) 15 years ago, flexible enteroscopy has become an established method in the diagnostic and therapeutic work-up of small bowel disorders. Various techniques for deep small bowel endoscopy have been developed since then, and are described in detail in other articles in this issue. All of the methods can be summed up under the generic term device-assisted enteroscopy. There are 2 main subgroups. First, there are balloon enteroscopy techniques, which all follow the push-and-pull principle; by contrast, spiral enteroscopy is based on the principle of rotation. Balloon enteroscopy can be further subdivided into 2 groups: balloon-guided enteroscopy and balloon-assisted enteroscopy, which can be performed with either 1 balloon (single-balloon enteroscopy [SBE]) or 2 balloons (DBE). Fig. 1 provides an overview of the different techniques. DBE was the first method introduced that allowed flexible enteroscopy without the need for surgery, and it is therefore also now the oldest. Considerable experience has been gained with the method in recent years, and most studies and publications on enteroscopy have been performed using DBE ( Fig. 2 ). This article provides an update on the indications for DBE, performance of the technique, and outcomes associated with it.
Indications
Any type of known or suspected small bowel disease may be an indication for an examination of the small bowel for either diagnostic or therapeutic purposes. Flexible small bowel endoscopy is generally performed for diagnosis, to check unclear lesions that have been identified using other imaging techniques, such as capsule or radiological methods; to obtain histologic data through biopsy sampling; or in patients with continuing symptoms and previously negative diagnostic work-up in whom there is a suspicion of a small bowel disorder. Therapeutic interventions include marking the bowel wall with India ink before laparoscopic surgery, any type of hemostatic procedure (injection, argon plasma coagulation, clipping), endoscopic resection, dilation, extraction of foreign bodies, percutaneous endoscopic jejunostomy, and implantation of self-expanding metal stents. Enteroscopy techniques are also needed for investigations in the upper gastrointestinal tract in patients who require certain types of bariatric surgery, and for endoscopic retrograde cholangiopancreatography (ERCP) in patients with surgically altered anatomy.
However, small bowel bleeding continues to be the main indication. There is still a certain amount of confusion in the terminology used to define gastrointestinal bleeding. The terms overt and occult describe the type of bleeding; bleeding that is either macroscopically visible (melena, hematochezia) or macroscopically invisible; the latter can only be detected using stool tests. The term obscure refers to bleeding from an unclear location. Before nonsurgical enteroscopy was available, gastrointestinal bleeding was divided into upper gastrointestinal bleeding, in which the bleeding source was located proximal to the ligament of Treitz (duodenojejunal flexure); and lower gastrointestinal bleeding, in which the bleeding source was distal to the ligament of Treitz. Because the small bowel was unknown territory for endoscopists before the introduction of capsule endoscopy and DBE, the term obscure gastrointestinal bleeding was used as a synonym for suspected small bowel bleeding. Since the introduction of enteroscopy methods, the definition of gastrointestinal bleeding has had to be redefined, as shown in Fig. 3 . The term obscure should now be used for bleeding that remains unclear after a negative diagnostic work-up including small bowel endoscopy.
Appropriate patient selection and correct choice of the enteroscopy device to be used are mandatory for successful management of midgastrointestinal bleeding. For appropriate patient selection, information is required about the type of bleeding; its severity (with a potential need for blood transfusion); and the patient’s medical history relative to anticoagulant medication, intake of nonsteroidal antiinflammatory drugs (NSAIDs), and prior abdominal surgery. The patient’s age and concomitant diseases also need to be taken into account. Before any kind of enteroscopy is started, it is important to have a clear idea of the most likely cause of the bleeding and to take the appropriate decision about which kind of enteroscopy device is likely to be best in the situation. The same also applies to other indications for enteroscopy.
In patients with chronic small bowel bleeding, the most common sources of bleeding are angiodysplasias, at least in Western countries. Argon plasma coagulation (APC) is therefore one of the most frequently used therapeutic methods. APC of angiodysplasias or vascular malformations is safe and effective, as various studies have shown. Malignancies and any types of erosion or ulceration caused by NSAIDs, Crohn disease, large polyps, and ischemia in surgical anastomoses are other possible sources of bleeding that can lead to chronic MGIB.
In patients with acute ongoing MGIB, DBE or other enteroscopy techniques are the methods of choice, in view of their high diagnostic and therapeutic yield. The main sources of acute bleeding are angiodysplasias in patients who are receiving anticoagulant medication, Dieulafoy lesions, any type of ulceration, and the rare conditions of Meckel diverticulum or small bowel varices. In cases of severe bleeding, emergency DBE is challenging and should be performed by staff members with experience in emergency endoscopy and enteroscopy.
In recent years, Crohn disease has increasingly become the focus of interest. In patients with Crohn, enteroscopy is performed to detect ulcerations and stenoses (which may have been missed on radiographic imaging) and for decision making regarding the subsequent medical or surgical management. A higher risk of perforation during DBE was found in the group of patients with Crohn disease and steroid medication. This risk should be taken into account when performing DBE in this group of patients.
Enteroscopy has also become important in patients with polyposis syndromes, because it provides the option of endoscopic resection in deeper parts of the small bowel without the need for surgery.
All of the common indications for enteroscopy are described in detail in other articles in this issue. The remainder of this article explains why DBE is the most promising technique for managing small bowel diseases such as bleeding, Crohn disease, and polyposis syndromes.
Performance
DBE was first introduced in Japan by the technique’s inventor, Hironori Yamamoto, in 2001 and in the Western hemisphere by our own group in 2003. Thanks to technical developments and improvements, several double-balloon devices for different indications are now available ( Table 1 ). The P type is the thinnest and its high flexibility allows deep insertion and complete enteroscopy in a high percentage of cases, even in difficult anatomic conditions. The T type has a slightly larger outer diameter, but consequently a larger working channel of 2.8 mm and 3.2 mm, respectively. The newer EN-580T device additionally provides easier handling for balloon insufflation and is a high-resolution endoscope ( Fig. 4 ). The larger working channel makes the T type useful for cases of acute bleeding and for dilation, as well as ERCP in patients with surgically altered anatomy (if the double-balloon colonoscope is too short for access). The double-balloon colonoscope can be recommended not only for difficult ileocolonoscopies but is also mainly used for ERCP in patients with surgically altered anatomy. As a result of the reduced length of the colonoscope, all standard accessories for ERCP can be inserted, whereas for the longer T type only specially designed instruments can be used. The new prototype of a short double-balloon endoscope (EI-580BT, Fujifilm, Japan) provides high resolution, greater bending at the tip of the scope, and easier handling for balloon insufflation. For children, another prototype is being developed with an outer diameter of 7.7 mm and a working channel of 2.0 mm. The availability of different double-balloon endoscopes is a great advantage, because appropriate device selection is one of the key points for successful enteroscopy. For SBE and spiral enteroscopy, only 1 device and prototype is available.
| Scopes | EN-450P5 | EN-450T5, EN-580T a | EC-450BI5, (EI-580 BT a , Prototype) |
|---|---|---|---|
| Length (cm) | 200 | 200 | 152 |
| Diameter (mm) | 8.5 | 9.4 | 9.4 |
| Working Channel (mm) | 2.2 | 2.8, 3.2 a | 2.8, 3.2 a |
| Main Areas of Application |
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DBE can be performed with the patients under sedoanalgetic medication. General anesthesia is only required in selected cases (eg, in children; in difficult procedures in younger patients, such as polypectomy of very large polyps; or in older patients with respiratory problems).
In the early days of enteroscopy, bowel cleansing was only recommended for the anal approach. However, in the opinion and experience of the present author, preparation with a cleansing solution in cases of oral DBE can be recommended in patients with slow transit, oral iron substitution, prior abdominal surgery with Roux-en-Y reconstruction, and in those with signs of intestinal obstruction or when very deep insertion is planned. For the anal approach, patients should be prepared with split-dose cleansing as in colonoscopy.
Outcome
Because DBE is the oldest technique for enteroscopy, there is considerable experience with the device and results from large databases are available. The complication rates with diagnostic enteroscopy, at up to 1%, are higher than with diagnostic upper and lower gastrointestinal endoscopy. However, they are acceptable because DBE is a much more complex investigation. As in conventional endoscopy, therapeutic interventions are associated with an overall complication rate of 3% to 4%, which is higher than with diagnostic procedures. Polypectomy of large polyps seems to be the intervention associated with the highest complication rate (up to 10%), especially during an endoscopist’s learning period with the method. The mortality is estimated at 0.05%. Altogether, the complication rate and mortality are lower than with intraoperative enteroscopy, which has morbidity rates of 15% to 20% and mortality of up to 5%; DBE also requires fewer staff. Intraoperative enteroscopy has consequently now become a method reserved for selected cases.
With appropriate patient selection, high diagnostic and therapeutic yields of 70% to 85% can be expected with DBE. One reason for this may be the second balloon at the tip of the scope, which helps to stabilize the position and facilitates insertion even in difficult conditions. It may also be less traumatic. In addition, the balloon at the tip of the scope can also be inflated during withdrawal, so that it pulls apart the pleated folds and may lead to a reduced rate of missed lesions.
Another reason for the high yield is the high percentage of cases in which complete enteroscopy can be achieved if needed. The first prospective trial comparing the 1-balloon and 2-balloon techniques showed that DBE was associated with a rate of complete enteroscopy that was 3 times higher. Complete enteroscopy is only required in approximately 20% of all patients. Achieving complete enteroscopy also represents an objective measure of the depth of insertion reached. Details are shown in Table 2 . The comparative studies by Takano and colleagues and Domagk and colleagues presented contradictory results. Although the prospective single-center study in Japan confirmed that DBE has significantly better results in relation to complete enteroscopy, the European multicenter trial did not find a significant difference ( Table 3 ). The problem with the latter trial was the generally very low rate of complete enteroscopy achieved, which was even less than the rate of 23% achieved in the German DBE registry. Appropriate training when endoscopists are starting to practice enteroscopy, and ensuring a medium to high volume of investigations, are important for effective handling of enteroscopy. Skill is one of the key issues, as is shown by the author’s own learning curve with an initial rate of complete enteroscopy of 45%, increasing up to approximately 90% within the following years.
| DBE (n = 50) | SBE (n = 50) | P Value | |
|---|---|---|---|
| Preparation Time | 10 min | 6 min | <.0001 |
| Investigation Time (Mean, Oral, and Anal) | 80–90 min | 75 min | <.0005 |
| Diagnostic and Therapeutic Yield | 72% | 48% | <.025 |
| Complete Enteroscopy | 66% | 22% | <.0001 |
| Complete Enteroscopy | P Value | ||
|---|---|---|---|
| DBE (%) | SBE (%) | ||
| Japanese Single-center Study | 57 | 0 | <.0001 |
| European Multicenter Trial | 18 | 11 | NS |
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