What is malrotation of the intestines?
Malrotation of the intestines is a misnomer because it is really nonrotation or incomplete rotation of the bowel. To understand malrotation, one must first consider normal embryologic rotation of the intestines. During normal embryologic development in the first trimester, the midgut leaves the abdominal cavity, travels into the umbilicus (umbilical cord), and subsequently returns to the abdominal cavity. As the intestines return, the proximal and distal parts of the midgut rotate around the superior mesenteric artery axis by 270 degrees in a counterclockwise direction. The ligament of Treitz (duodenojejunal junction) lands in the left upper quadrant, and the cecum comes to rest in the right lower quadrant. In malrotation, this intestinal rotation and fixation occur abnormally. If normal rotation does not occur, the cecum is not anchored in the right lower quadrant and may be in the midline or in the upper abdomen, and the small bowel is not anchored in the left upper quadrant and may lie entirely in the right hemi-abdomen.