Malrotation is the most common congenital anomaly of the small intestine. It is estimated that 1 in 200 live births has an asymptomatic rotational anomaly; however, symptomatic malrotation occurs less frequently (1 in 6000 live births).
During embryonic development, the primitive bowel protrudes from the abdominal cavity. As it returns to the abdomen, the large bowel normally rotates counterclockwise, with the cecum coming to rest in the right lower quadrant. Incomplete rotation, in which the cecum ends up elsewhere (usually in the right upper quadrant or midepigastrium), may cause bowel obstruction due to retroperitoneal bands (Ladd bands) that stretch across the duodenum or due to a volvulus of the small bowel, which, lacking its normal peritoneal attachment, twists on its narrow, stalk-like mesentery (1).
Other malformations occur in 30 to 60% of patients, most commonly other gastrointestinal (GI) malformations (eg, gastroschisis, omphalocele, diaphragmatic hernia, intestinal atresia, Meckel diverticulum). Cardiac anomalies are next most common, including heterotaxy syndrome (a condition in which the internal organs are abnormally arranged in the chest and abdomen).
Patients with malrotation can present in infancy or in adulthood; however, 30% present in the first month of life and 75% in the first 5 years of life. Patients can present with acute abdominal pain and bilious emesis, with an acute volvulus, with typical reflux symptoms, or with chronic abdominal pain. In some patients, malrotation is found incidentally as part of an evaluation for another problem.
Bilious emesis in an infant is an emergency and should be evaluated immediately to make sure the infant does not have malrotation and a midgut volvulus; untreated, the risk of bowel infarction and subsequent short bowel syndrome or death is high.
In infants with bilious emesis, plain x-rays of the abdomen should be done immediately. If they suggest obstruction, for example showing a dilated stomach and proximal small bowel (double-bubble sign), a paucity of bowel gas distal to the duodenum, or both (suggesting a midgut volvulus), further diagnosis and treatment must be done emergently. Barium enema typically identifies malrotation by showing the cecum outside the right lower quadrant. If the diagnosis remains uncertain, an upper GI series can be done cautiously.
If plain x-rays are nonspecific and no obstruction is present, clinicians sometimes begin with an upper GI series because this may detect other conditions that cause similar symptoms.
In nonemergent situations, the definitive imaging for malrotation is an upper GI series. Studies have investigated the use of ultrasonography to diagnose malrotation by looking for retromesenteric localization of the third portion of the duodenum, or reversed mesenteric vessel position and the whirlpool sign (bowel wrapped around the superior mesenteric artery in a whirlpool-like pattern). The use of ultrasonography depends on the availability of an experienced radiologist or radiology technician. For now, an upper GI series is the standard diagnostic technique for malrotation with or without volvulus (1, 2).
1. Graziano K, Islam S, Dasgupta R, et al: Asymptomatic malrotation: Diagnosis and surgical management: An American Pediatric Surgical Association outcomes and evidence based practice committee systematic review. J Pediatr Surg 50:1783–1790, 2015. doi: 10.1016/j.jpedsurg.2015.06.019
2. Zhou LY, Li SR, Wang W, et al: Usefulness of sonography in evaluating children suspected of malrotation: Comparison with an upper gastrointestinal contrast study. J Ultrasound Med 34:1825–1832, 2015. doi: 10.7863/ultra.14.10017
The presence of malrotation and midgut volvulus is an emergency requiring immediate surgery, which is a Ladd procedure with lysis of the retroperitoneal bands and relief of the midgut volvulus. The Ladd procedure can be done laparoscopically or as an open procedure. Doing the Ladd procedure laparoscopically for malrotation without volvulus may decrease the time until enteral nutrition is reintroduced and reduce the length of hospital stay compared to an open procedure (1).
When malrotation is found incidentally in an asymptomatic child, the Ladd procedure should be considered given the potentially devastating outcome of a volvulus; however, doing this procedure in this situation is controversial.
During embryonic development, the bowel begins outside the abdominal cavity and then returns to the abdomen and rotates; incomplete rotation may cause bowel obstruction.
Patients are often asymptomatic but some have mild, nonspecific symptoms (eg, reflux), or manifestations of life-threatening bowel obstruction (eg, bilious emesis) due to volvulus.
Other malformations, typically gastrointestinal (GI), are present in 30 to 60% of patients.
Do GI x-rays and upper GI series and/or barium enema.
Do surgical repair for symptomatic infants.