Normal Postsurgical Anatomy

Fig. 7.1

Roux-en-Y gastric bypass

Modifications to be aware of on endoscopy include the presence of a loop instead of a Roux gastrojejunostomy, whether the gastric bypass is divided or nondivided; the length of the Roux limb, whether the gastric pouch is horizontally or vertically oriented; and the use of restrictive prostheses proximal to the gastrojejunostomy.

For most patients with a RYGB, a standard gastroscope can be used to evaluate the esophagus, gastric pouch, gastrojejunal anastomosis, and proximal portion of the Roux limb. A pediatric colonoscope or enteroscope may be required to examine the jejunojejunal anastomoses. Pouch size can be determined by measurement of pouch length using endoscope markings and estimation of pouch diameter. Gastrojejunostomy aperture can be measured using a standard polypectomy snare, and inability to pass a 9 mm endoscope is usually diagnostic of stomal stenosis.

Once the end of the esophagus is reached, the endoscopist must pass the scope through the gastroesophageal junction area very slowly and carefully, as the restrictive pouch is usually 26 cm or less in length. The esophagus and gastroesophageal junction should appear normal following gastric bypass. A small amount of suture material at the gastrojejunal anastomosis and mild focal erythema of the gastric pouch may be normal findings, depending upon how soon postoperatively the endoscopy occurs [7]. All other mucosal findings would be considered abnormal. There is a short blind limb of jejunum just distal to the gastrojejunostomy in addition to the Roux limb. This represents the “candy cane” portion of the end-to-end anastomosis. Long, blind limbs can result in symptoms, including abdominal pain and nausea. Use of the pediatric colonoscope or enteroscope is helpful when examining the Roux limb to evaluate for evidence of obstruction. Thus, it is helpful to know beforehand the length of the roux limb or if a loop jejunostomy is present. Presence of more than one opening signifies a break in the staple line, and this should be differentiated from the true anastomoses. This occurs more commonly when the stomach is stapled in continuity than when the gastric pouch was completely transected from the excluded stomach.

Evaluation of the bypassed stomach and biliopancreatic limb is challenging and not routinely done. A double-balloon enteroscope may be used to examine these inaccessible segments. This enteroscope uses two balloons, one attached to the tip of the endoscope and the other to the distal end of the soft overtube with fluoroscopic assistance in a retrograde fashion [8]. Another technique described for potential ERCP access in these patients involves advancing a duodenoscope over a stiff guidewire previously placed through the pylorus by using a forward-viewing endoscope [9]. If the duodenoscope cannot be advanced to the papilla, a large-diameter balloon (18 mm) is passed retrograde through the pylorus and inflated, and the duodenoscope is then pulled into the afferent limb.

Biliopancreatic Diversion

This was the successor to the jejunoileal bypass procedure. The principle was to ensure that no limb of intestine was left without flow through it. Scopinaro et al. described the BPD. It involves the following:

Horizontal partial gastrectomy, leaving 200–500 mL of proximal stomach, with closure of the duodenal stump
Gastrojejunostomy with a 250 cm alimentary Roux limb
Anastomosis of the long biliopancreatic limb to the Roux limb, 50 cm proximal to the ileocecal valve, creating an extremely short common channel [10, 11]

The stoma of the gastroenterostomy was 2–3 cm. This procedure involves two key components: a distal gastrectomy, which results in mild reduction of oral intake, and construction of a long-limb Roux-en-Y anastomosis with a short, 50 cm common alimentary channel (Fig. 7.2).

Fig. 7.2

Biliopancreatic diversion (BPD)

On endoscopy, the gastric pouch composed of the body of the stomach is visualized. A horizontally oriented intact staple line should be observed. The gastroenterostomy should be accessed with ease with a standard gastroscope passing directly through to the jejunum.

Biliopancreatic Diversion with Duodenal Switch

The Hess and Hess modification of the BPD in the 1990s involved the introduction of the duodenal switch (biliopancreatic diversion with duodenal switch, BPDS) [12]. These modi-fications included the following:

Making a lesser curvature gastric tube with a greater curvature gastric resection, rather than performing a horizontal gastrectomy
Pyloric preservation
Anastomosing the enteric limb to the proximal duodenum
Dividing the duodenum, with closure of the distal duodenal stump
There is no consensus regarding the lengths of the enteric and biliopancreatic limbs and the common channel as well as the method for performing the duodenoileostomy. Thus, pre-endoscopic review of the patients’ operative reports is essential.

In Marceau et al.’s version of the duodenal switch, the duodenum is cross-stapled distal to the duodenoileostomy, without dividing the duodenum [13].

BPDS involves removal of most of the greater curvature by tubularizing the stomach and taking a transection of the duodenum 2 cm distal to the pylorus, followed by end-to-end duodenoileostomy. A Roux-en-Y anastomosis is created between the biliopancreatic limb and the distal ileum with a short common channel (Fig. 7.3).

Fig. 7.3

Biliopancreatic diversion with duodenal switch (BPDS)

On endoscopy, a vertically oriented gastric sleeve is observed. The pylorus and the proximal duodenum are visualized. Assessment of the integrity of the gastric staple line as well as ease of passage through the duodenoileostomy anastomosis into the ileum is crucial.

Purely Restrictive Procedures

These include the gastroplasty (vertical or horizontal), gastric banding (fixed or adjustable), and sleeve gastrectomy procedures. For restrictive procedures, identification of normal anatomy is critical to identify issues that could lead to inadequate weight loss and weight regain.

Gastroplasty

Restrictive procedures depend on restriction of intake as the main mechanism, so a small measured pouch and a controlled outlet are crucial to success.

Printen and Mason performed the first restrictive bariatric surgery procedure in 1971 [14]. While initially gastroplasties were horizontally oriented, now they are only of historical interest, as they were associated with various problems, including difficulty performing endoscopy when obstructed [14]. This led to the change from horizontal to vertical orientation in the early 1980s, and pouches were moved to the lesser curvature to facilitate endoscopy [15].

The key components of vertical banded gastroplasty (VBG) include a vertically oriented gastric channel (pouch) that has a volume of 50 mL or less and an outlet (stoma) from the channel into the remainder of the stomach. The stoma is reinforced by a polypropylene mesh collar or a silastic ring to prevent stomal dilation (Fig. 7.4) [16, 17]. The remainder of the stomach and small intestine are unaltered in this procedure.