With considerable variability in postsurgical anatomy, preprocedure planning is essential. When adequately prepared, the endoscopist can decrease the procedure duration, select the appropriate endoscope, and have the appropriate tools available at the time of endoscopy. Most importantly, the previous operative report should be obtained, recent cross-sectional imaging reviewed, and if possible, a discussion with the surgeon who performed the original operation [11]. Depending on operator expertise and difficulty of the procedure, the range of times reported for ERCP in altered anatomy can vary from 24 to 150 min [12–14]. The increased complexity and longer procedure duration in patients with postsurgical anatomy may necessitate the use of an anesthesiologist, as adequate (and safe) sedation almost certainly plays a role in affecting the procedure outcome. Several groups have reported improved intubation depth, patient comfort, and decreased overall procedure duration with the use of CO₂ for procedures employing BAE [15, 16].

In patients with short afferent limbs, such as those with Billroth II gastrojejunostomy, a duodenoscope may suffice and provides the benefit of both an elevator and availability of standard ERCP tools. In patients with longer limbs, success has been reported with either the 164 cm long pediatric colonoscope or 240 mm long “standard” enteroscope [7, 17] both with and without the assistance of a gastric overtube. Gastric overtubes may reduce looping in the stomach and duodenum; in patients who have undergone gastrectomy, gastric overtubes are rarely needed. If a colonoscope is used, it is preferable to use one with a variable stiffness setting. Initial insertion is performed on the most flexible setting and the stiffness is increased once the endoscope is passed into the small intestine to reduce loop formation. In patients with longer intestinal limbs, it may be necessary to use the “hook and pull” technique to advance the endoscope deeper into the small intestine. The use of a colonoscope to place a wire into the pancreatico-biliary limb in patients with Roux-en-Y anatomy followed by advancement of a duodenoscope over the wire has been described [17]. More recently the advent of overtube-assisted enteroscopy (both BAE and RE) has allowed the endoscopist a means to navigate tight angulation at the anastomosis and very long Roux limbs to access the pancreatico-biliary tree.

Several techniques are now available to perform overtube-assisted deep enteroscopy including the double balloon enteroscopy (DBE), single balloon enteroscope (SBE), and RE. In general, RE and balloon-assisted enteroscopy (BAE) consist of a forward viewing enteroscope that travels through a flexible overtube. As such, overtube-assisted enteroscopy is a term that can encompass both RE and BAE. RE utilizes a rotating overtube that sequentially reduces and pleats the small bowel over a standard enteroscope. In the case of BAE, there is either a balloon on the distal tip of the overtube (single balloon) or a balloon on both the overtube and the distal tip of the enteroscope (double balloon). The operator is able to inflate or deflate the balloons selectively. Using a push-pull technique, BAE works by pleating the bowel over the endoscope as it is advanced, using balloons to stabilize the device for both forward progress and reduction. With a double balloon, the endoscope is advanced and the balloon at the tip of the endoscope is then inflated, anchoring the scope tip. The overtube is then advanced over the endoscope and, once the overtube has reached the end of the scope, the overtube is inflated and either reduction can be performed or the endoscope balloon can be deflated and advanced further. The single balloon technology works in the same fashion, though without a balloon over the endoscope tip. This sacrifices a degree of stability but provides added flexibility, faster set-up time, and decreased complexity of balloon coordination [18].

Several authors have reported conceptualizing the overtube as a “large working channel” to assist ERCP [19–21]. Once the enteroscope is advanced to the ampulla or the pancreatic or biliary anastomosis, the balloon is inflated on the overtube and reduction is performed. This anchors the overtube and the enteroscope is then removed. In the case of longer overtubes, an incision can be made in the overtube just outside of the patient (taking care not to damage the balloon air channel) and a gastroscope or ultraslim gastroscope can be advanced to the ampulla. This allows passage of standard-biliary tools such as stents [20] that are precluded by the long and narrow working channel of the enteroscope, or direct cholangioscopy [21, 22].

Regardless of anatomy, selecting the appropriate limb to traverse can be the first challenge reached by the endoscopist. Selecting the wrong limb adds time to an already lengthy procedure. In general, the endoscopist will encounter two or three potential lumens (Fig. 15.1) at the surgical anastomosis. If three lumens are visualized, invariably one of the openings is not a true opening, rather a “blind end,” created by the end-to-side creation of the anastomosis. The passage visualized directly adjacent to this lumen is usually the efferent limb. Between these openings one should not see a surgical scar. If the efferent limb is entered and traversed for some distance the endoscopist will generally see multiple loops forming on fluoroscopy. Bile is not a reliable marker to indicate the afferent limb, though generally a greater amount of bile is found in the afferent limb. One group has reported improved identification of the afferent limb in patients with Roux-en-Y anatomy by injecting indigo carmine just beyond the stomach or the esophagojejunostomy. When the anastomosis is then reached, the afferent limb reportedly took up less indigo carmine and thus decreased time of procedure with little added expense or technical challenge [23].

It is not uncommon for endoscopists to become disoriented at the site of the anastomosis and, after accidentally traversing the efferent limb, reintubate the incorrect lumen. Once the appropriate limb has been determined, several groups advocate tattooing the afferent limb for improving ease of future access [24, 25]. Others recommend tattooing the limb that is initially intubated to prevent reintubation if this becomes the incorrect limb [26]. In either circumstance, clear documentation of which limb was tattooed is essential to expedite future endoscopy.

The second challenge to successful afferent limb intubation is navigating an often acute angulation. The afferent limb is generally located at 5–8 o’clock and should take off at a right angle—essentially an almost 180° turn once the endoscope is inserted into the Roux-en-Y anastomosis. If a variable stiffness colonoscope is used, making this turn should be attempted using the most flexible setting. Occasionally, changing the patient’s position to left lateral decubitus or applying abdominal pressure can help navigate the turn. Fluoroscopy often can help confirm passage in the proper direction. If BAE systems are used, it is useful to reduce the scope as much as possible once the jejuno-jejunal anastomosis is reached (in the case of a Roux-en-Y anastomosis). Following reduction, the tip of the endoscope is advanced as deep as possible into the pancreatico-biliary limb. The balloon at the tip of the endoscope is then inflated and the endoscope tip is “hooked” into the limb using a combination of tip deflection and suction while the overtube is advanced through the anastomosis and into the pancreatico-biliary limb [5]. Despite these maneuvers, further advancement can be impossible. In these instances, a wire can be advanced downstream under fluoroscopy and a large balloon advanced over the wire. Using this balloon as an anchor, the enteroscope can be slowly inched forward [27].