Malrotation of the bowel

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Malrotation of the bowel is failure of the bowel to assume its normal place in the abdomen during intrauterine development. Diagnosis is by abdominal x-ray. Treatment is surgical repair.
(See also Overview of Congenital Gastrointestinal Anomalies.)
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.
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.