The indications for BAE have increased significantly since its introduction in 2004. Currently, BAE techniques are not only used to perform deep enteroscopy, but the equipment can also be used for endoscopic retrograde cholangiopancreatography (ERCP), incomplete colonoscopies, or exploring the gastrointestinal tract of patients with surgically deranged anatomy [16–28] (Fig. 7.3). Table 7.1 lists indications for BAE. Furthermore, BAE has become an important tool to deliver various types of endoscopic therapies during deep enteroscopy, but also for many other gastrointestinal problems, such as insertion of self-expanding metal stents into the small bowel or into the stomach in patients with deranged anatomy [22–26] (Table 7.1, Figs. 7.4 and 7.5).

We will separately describe the equipment and technique used for overtube-based BAE and through-the-scope balloon-guided enteroscopy.

We prefer to use general anesthesia when performing oral (antegrade) BAE. When using general anesthesia we prefer to place the patient on their back (i.e., supine). This position will also allow for easy external manual compression when this is needed to improve advancement of the scope. When conscious sedation is utilized, left-lateral decubitus positions are mandatory, so that the patient’s secretions can be managed properly and thus aspiration avoided [13]. We use moderate sedation for the majority of our patients undergoing anal (retrograde) BAE.

Both techniques of SBE and DBE, similar to overtube-assisted push enteroscopy, use the principle of the push-and-pull technique using the overtube: The endoscope is first inserted (pushed) into the small bowel, then the overtube is advanced toward the tip of the endoscope, and then both endoscope and overtube are pulled back; hence the name “push and pull” (Fig. 7.6) [13]. This standard approach to BAE requires two people, the operator and an assistant. The assistant holding the overtube plays a crucial role, as a stable overtube will positively influence the depth of insertion and the maneuverability of the scope [13]. When using SBE and DBE, the major factor governing the depth of insertion of the enteroscope is the presence of the balloon on the distal end of the flexible overtube. The overtube stabilizes the intestine, preventing it from bending or looping [13, 30]. Although, the overtube stabilizes the intestine, preventing it from bending or looping, the key action of the inflated overtube balloon is to shorten the small bowel proximally (Fig. 7.6a). The inflated balloon prevents the intestine from sliding forward while the scope is being pushed or advanced forward (Fig. 7.6b) [13, 30]. This allows the endoscopist to firmly push on the enteroscope, effectively transmitting forces to the distal end of the endoscope and hence permitting the advancement of the enteroscope deeper into the small bowel without looping or stretching of the proximal intestine [1–8, 10, 13, 30]. The key steps and aspects of BAE are listed in Table 7.3 and shown in Fig. 7.6 and Video 7.2.