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A number of rotational abnormalities have been described which correlate with abnormal embryologic development of the midgut. Intestinal rotation during embryologic development of the bowel was described by malrotation of the bowel. The incidence of malrotation is 1 in 500 live births. Twenty-five to 40% of patients with symptomatic malrotation present within the first week of life, 50% present within the first month, 75% present prior to 1 year of age, and the remaining 25% present after 1 year of age with equal occurrence in males and females. There is a 2:1 male predominance in cases presenting in the neonatal period. Infants and children with displaced viscera as a result of other developmental abnormalities such as gastroschisis, omphalocele, or congenital diaphragmatic hernia always have rotational abnormalities owing to lack of fixation. Malrotation has also been associated with small bowel atresia, Meckel's diverticulum, intussusception, Hirschsprung's disease, GER, gastric volvulus, persistent cloaca, and extrahepatic biliary anomalies.
Extracoelomic development of the fetal intestine occurs between the 4th and 12th weeks. Initially, development of the midgut occurs with rapid elongation of the primary intestinal loop. The superior mesenteric artery (SMA), supplying the small bowel and proximal colon, acts as the primary blood supply to these segments and the axis of their subsequent rotation.
Lack of fixation of the small bowel results in obstructing, peritoneal adhesive bands (Ladd's bands) forming between the cecum and the right lateral abdominal wall causing compression of the duodenum and mechanical obstruction. Furthermore, the small bowel becomes suspended from a narrow pedicle (containing the SMA) like a bell clapper. As a result, the small bowel may then twist, in a clockwise direction, about this narrow axis resulting in midgut volvulus (MGV) and ischemia. This is the most catastrophic consequence of malrotation. Volvulus occurs in 68% to 71% of neonates with malrotation and up to 41% in older children.
Malrotation typically presents in the first month of life with bilious vomiting and a sudden onset of abdominal pain in an otherwise healthy infant. In infants of this age, this presentation should be considered malrotation with MGV until proven otherwise.
Physical ExaminationTorres, in a review of 22 patients undergoing surgery for malrotation, reported a normal abdominal examination in 50%. Another 32% had abdominal distension without tenderness. Because the obstruction is very proximal, abdominal distension.
Diagnostic StudiesA high index of suspicion of malrotation in the neonate with bilious vomiting must be maintained to prevent the devastating consequences.
Rapid fluid resuscitation and immediate laparotomy is required in patients suspected of having MGV. In the emergency room, a nasogastric tube is placed and broad-spectrum antibiotics are administered. At operation, the MGV is untwisted in a counterclockwise