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Malrotation and Volvulus : Embryology: The rotation and normal fixation of the intestinal tract takes place within the first three months of fetal life. In the earliest stages when the intestinal tract is recognizable as a continuous tube, the stomach, small intestine, and colon constitute a single tube with its blood supply arising posteriorly. The midgut portion of this tube, from the second portion of the duodenum to the mid-transverse colon, lengthens and migrates out into an extension of the abdomen, which lies at the base of the umbilical cord. Here this loop of bowel undergoes a 270-degree counterclockwise twist at its neck. In the center of the twisted loop lie the blood vessels that will become the superior mesenteric artery and vein. After rotation, the small intestine quite rapidly
withdraws into the abdominal cavity, with the duodenum and the proximal jejunum going first. During this
process the duodenojejunal junction goes beneath and to the left of the base of the superior mesenteric
vessels. This leaves the upper intestine, including the stomach and the duodenum, encircling the superior mesenteric vessels like a horseshoe with its opening on the left side of the embryo. The small intestine then follows into the abdomen, and withdrawal of the right half of the colon takes place so that it lies to the left. At the next step, the cecum and the right colon begin to travel across the top of the superior mesenteric vessels and then down to the right lower quadrant. The colon now lies draped across the top of the superior mesenteric vessels, again like a horseshoe, with its opening placed inferiorly. The duodenojejunal loop is said to attach to the posterior abdominal wall soon after its turn, whereas the mesenteric attachments of the entire colon and of the remaining small bowel gradually adhere after they arrive in their normal positions. In malrotation the right colon can create peritoneal attachments that include and obstruct the third portion of the duodenum (Ladd's bands).
The diagnostic hallmarks are: bilious vomiting (the deadly vomit), abdominal distension and metabolic
acidosis. A UGIS is more reliable than barium enema, most patients present in first month of life (neonatal), but may present at any time.
The treatment is immediate operation; volvulus often means strangulation. Needs fluid and electrolyte
replacement. Ladd's procedure consist of: reduce volvulus with a counterclockwise rotation, place small bowel in right abdomen, lysed Ladd's bands, place large bowel in left abdomen, do an appendectomy. In cases of questionable non-viable bowel a second look procedure is required.
Failure to make early diagnosis and operate may lead to dead midgut with resultant short bowel
syndrome.
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