This procedure is made necessary, as well as technically possible, by the embryologic rotation of the gut. A knowledge of this developmental process enables a rational approach to the procedure.

The gut can be divided into foregut, midgut, and hindgut. For the purposes of the general surgeon operating on the abdomen, these divisions can be defined as follows: the foregut is that portion of the gut supplied by the celiac artery, the midgut is that portion supplied by the superior mesenteric artery, and the hindgut is that portion supplied by the inferior mesenteric artery. Foregut derivatives in the abdomen include the distal esophagus, the stomach, and the duodenum to just distal to the major duodenal papilla. The liver and biliary apparatus arise as the hepatic diverticulum from the terminal foregut, whereas the pancreas arises from a diverticulum of the hepatic diverticulum and from a separate dorsal pancreatic bud. Midgut derivatives include the rest of the duodenum, all of the small intestine, the appendix, the cecum, the ascending colon, and the proximal two-thirds of the transverse colon. Hindgut derivatives include the distal one third of the transverse colon, the descending colon, the sigmoid colon, the rectum, and the anal canal to the anal valves.

The development of the abdominal gastrointestinal tract can be understood as a consequence of two phenomena. One of these is differential growth of the gut components in comparison to each other and to the developing peritoneal cavity. The other is the fusion and later degeneration, of apposed serosal surfaces. What follows is a conceptual description of some of the surgically relevant facets of the development of the infradiaphragmatic gastrointestinal system.

Initially, the gut is a midline intraperitoneal tube suspended from the dorsal body wall along its entire length by the dorsal mesentery. A ventral mesentery attaches the foregut to the anterior body wall from the umbilicus to the diaphragm, carrying the left umbilical vein from the umbilicus to its ultimate union with the caval system. As the fusiform dilatation destined to become stomach begins to develop by rapid elongation, the duodenum assumes the form of a C-shaped loop, with its convexity directed ventrally. Soon after these structures begin to be recognizable, the stomach changes its position by rotating 90 degrees to the right about its longitudinal axis. The end result of this rotation is that the right side of the stomach becomes the definitive posterior side and the left side becomes the definitive anterior side. Moreover, the original dorsal border becomes the greater curvature and the ventral border becomes the lesser curvature. As a result of the positional changes of the stomach, the C-loop of the duodenum rotates about a longitudinal axis so that the convex border becomes its definitive right border. This causes the right side of the duodenum and the right leaf of the mesoduodenum to be in apposition to the dorsal parietal peritoneum. The apposed serosal surfaces soon fuse and then degenerate, placing the bulk of the duodenum and pancreas, which develops primarily within the mesoduodenum, in a retroperitoneal position.