Clinical meaning
Intestinal malrotation is a congenital anomaly resulting from incomplete or abnormal rotation and fixation of the midgut during embryological development. During the 4th to 12th week of gestation, the midgut (which will become the distal duodenum, jejunum, ileum, cecum, appendix, ascending colon, and proximal two-thirds of the transverse colon) herniates out of the abdominal cavity through the umbilical ring into the extraembryonic coelom due to rapid growth of the intestine outpacing the growth of the abdominal cavity. During its return to the abdomen between the 10th and 12th week, the midgut normally undergoes a 270-degree counterclockwise rotation around the axis of the superior mesenteric artery (SMA). After rotation is complete, the mesentery anchors broadly across the posterior abdominal wall from the ligament of Treitz (duodenojejunal junction in the left upper quadrant) to the ileocecal junction (cecum in the right lower quadrant). This broad-based mesenteric attachment prevents the bowel from twisting on its vascular pedicle. When rotation is incomplete, arrested, or reversed, the mesentery has a narrow pedicle attachment rather than a broad base. This narrow mesenteric pedicle creates a critical risk: the entire midgut can twist around the SMA axis, producing a midgut volvulus. Volvulus compromises blood flow through the superior mesenteric artery and vein, causing intestinal ischemia, necrosis, and potentially catastrophic short bowel syndrome or death if not surgically corrected within hours. Additionally, with malrotation, peritoneal fibrous bands called Ladd bands may extend from the malpositioned cecum across the duodenum, causing extrinsic duodenal obstruction independent of volvulus. Approximately 75-85% of patients with symptomatic malrotation present within the first month of life, with most presenting in the first week. The hallmark presentation is bilious (green) vomiting in a neonate, which is a surgical emergency until proven otherwise because it may indicate midgut volvulus with impending intestinal necrosis.