Intestinal malrotation


Intestinal malrotation is a congenital anomaly resulting in the lack of or incomplete rotation of the fetal intestine around the axis of the superior mesenteric artery. Symptoms usually present in early childhood, but are rarely seen in adults. Rotational anomalies, which may or may not be symptomatic, are estimated to occur in between 1/200 and 1/500 live births [1,2] and incidentally are discovered later in life at surgery for other conditions [3-5]. Symptomatic malrotation is estimated to occur in 1/6000 live births [1,6]. Rare adult cases have been reported [7-10]. Adult-age intestinal malrotation has a nonspecific presentation and is difficult to diagnose due to progressively decreasing suspicion for malrotation in the older population.

Intestinal malrotation is any deviation from the normal 270 degree counterclockwise rotation of the midgut around the superior mesenteric artery that begins at the 6th gestational week with a prolapse into the umbilical cord and return of the midgut into the abdominal cavity between the 10th and 12th week. This rotation has been divided into 3 stages and anomalies in rotation are associated with each stage:

Stage I anomalies are nonrotation anomalies where the midgut fails to return to the abdomen, developing an omphaloceles.

Stage II anomalies are duodenal malrotation anomalies that include nonrotation, malrotation, reversed rotation and paraduodenal hernias.

Stage III anomalies are combined duodenal and cecal malrotation anomalies that include an unattached duodenum, mobile cecum, internal hernias, midgut volvulus, incomplete fixation of hepatic flexure of the colon, intermittent duodenal obstruction by Ladd bands and an unattached small bowel mesentery [11,12]. Ladd bands are bands fixing the duodenum to the retroperitoneum and cecum that continue to form in spite of incomplete rotation of the cecum [13].