Gastric Bypass Surgery

In this article, we will discuss Gastric Bypass Surgery (Overview). So, let’s get started.

Gastric bypass

The gastric bypass procedure was developed in the late 1970s and consisted of a horizontal
partitioning of the upper stomach to create a small gastric pouch. Gastrointestinal (GI) continuity was reestablished with a gastrojejunostomy (Figure 1). Initially a loop of jejunum was utilized (Figure 2). A shift to Roux-en-Y reconstruction of continuity soon followed due to a high incidence of complications of bile reflux associated with the loop procedure. Gastric bypass has evolved over the 30 years following its initial description to include multiple modifications. The size of the gastric pouch has gradually been reduced to the present 20-30-ml capacity. The gastric pouch is most commonly
constructed by dividing, rather than partitioning, the stomach to avoid potential creation of gastrogastric fistulae by partial or complete disruption of the staples (Figure 3). The development of devices that staple and divide the stomach simultaneously facilitated this advancement.

Various lengths of small intestine have been used for construction of the Roux-en-Y limb. The following ter-
minology has evolved regarding these limbs (Figure 3). Biliopancreatic limb: the limb of jejunum extending from the ligament of Treitz to the jejunojejunostomy, which is the point at which the nutrient stream, the
bile, and pancreatic secretions come together. This limb is typically 30-60 cm in length in gastric bypass procedures.

Alimentary limb: the Roux limb that extends from the gastrojejunostomy to the jejunojejunostomy. This limb transmits the ingested nutrients in the absence of bile and pancreatic juice. The length of this limb is typically 75-150 cm, although longer lengths may be used. A Roux or alimentary limb >150 cm is referred to as a long limb or distal gastric bypass (Figure 4).

Common channel: the remainder of the small intestine from the jejunojejunostomy distally to the ileocecal valve. The length of this segment of intestine is typically not measured and is highly variable depending on the total length of the small intestine. The common channel usually constitutes the majority of the small intestine.

The gastrojejunostomy is generally constructed using 1 of 3 techniques. The first, hand suturing, creates an anastomosis that varies from 1-2 cm in diameter. With a second technique, circular stapling, the anastomosis may be reinforced with additional sutures or sealant. The diameter of the anastomosis varies from 1-2 cm based on the specific device utilized. Finally, a side-to-side stapled anastomosis can be used with suture closure of the defect for placement of the stapling device. The anastomosis
produced by the side-to-side technique also varies between 1-2 cm in diameter.

Figure 1. Gastric bypass partitioned. In this version of gastric bypass, the stomach is partitioned rather than divided. A Roux-en-Y gastrojejunostomy is done with variable lengths. The alimentary limb refers to the jejunal Roux-en-Y limb anastomosed to the stomach. The biliopancreatic limb transmits bile and pancreatic secretions to the jejunojejunos-
tomy where the ingested nutrients and digestive juices first mix. The common channel refers to the distance from the enteroenterostomy to the ileocecal valve.
Figure 2. Gastric bypass loop. In this example, the stomach has been divided rather than partitioned. Rather than a Roux-en-Y limb, a loop gastrojejunostomy is done. Bile reflux gastritis and esophagitis are problematic with this procedure.
Figure 3. Retrocolic Roux-en-Y gastric bypass. This diagram depicts the anatomic details for the most common gastric bypass. The Roux-en-Y limb may be transmitted to the small gastric pouch either anterior or posterior to the colon and stomach.
Figure 4. Long-limb Roux-en-Y gastric bypass. Variable lengths for the alimentary and biliopancreatic limbs and the common channel have been used in an effort to achieve maximum outcomes. If the Roux-en-Y or alimentary limb is >150 cm in length, the procedure is generally termed a long-limb Roux-en-Y gastric bypass.

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