Gastrointestinal (GI) malrotation, sometimes referred to as incomplete rotation or intestinal nonrotation, is any deviation from the physiological rotation and/or fixation of the GI tract during embryonic development.
During the development of the GI tract, the 3 parts of the tract, namely the fore-, mid- and hindgut, normally bulge out of the abdominal cavity and undergo a counterclockwise rotation of 270 degrees. This rotation occurs around the superior mesenteric blood vessels. Following its physiological rotation, the gut then returns the cavity within the abdomen where it is fixated at the duodenojejunal junction and cecum.
Embryological Rotation of the Midgut
Patients presenting with GI malrotation may have a distended abdomen with tenderness accompanied by guarding (tensing of the abdominal muscles) on physical examination. Abnormal rotation of the GI tract can lead to comprised vascular supply to the affected portions of the intestines and this in turn can cause intraluminal hemorrhage, which manifests as hematemesis (vomiting blood) and/or melena (blood in stools).
In addition to hemorrhage, patients may develop shock with signs such as a decrease in urine output, low blood pressure, and poor perfusion. Other signs of compromised vascular supply include inflammation of the peritoneum and skin discoloration.
GI malrotation, has been recently suggested to result from genetic mutations. The gene implicated is the fork head transcription factor (FOXF1) gene. In addition to abnormal rotation, it has been cited that these patients may also have congenital short bowel. FOXF1 is believed to play a crucial role in mediating the physiological rotation of the intestines and the forming of the dorsal mesentery.
Inactivating mutations of this gene may result in GI malrotation. In addition to a mutation in FOXF1, mutations in genes that control left-right (L-R) patterning in the embryo and other genes not yet identified may also be associated with GI malrotation.
There are four suggested etiological groups for GI malrotation: (i) abnormal L-R patterning, (ii) dorsal mesentery, (FOXF1) anomalies, (iii) irregularities of the intestine itself, and (iv) abnormalities of other abdominal contents.
Irregularities of the intestine itself include atresias (closed or missing orifices/passages) and congenital short bowel. The fourth category has been postulated on the basis of incorrectly placed intestines and/ or abdominal organs within the abdominal cavity during organogenesis, which subsequently leads to GI malrotation.
In the United States, for example, asymptomatic GI malrotation occurs with an incidence somewhere between 1 in 200 to 1 in 500. Symptomatic GI malrotation, on the other hand, has a much lower incidence, being somewhere around 1 in 6000 live births. Nearly 80% of patients will present with malrotation within their first year of life.
Moreover, the incidence in males is double that of females in those patients younger than 1 year. Up to 6 out of every 10 children with GI malrotation may have an accompanying congenital anomaly. By default, all children with hernia of the diaphragm, omphalocele (protrusion of abdominal organs into umbilical cord), and gastroschisis (intestines protruding through the abdominal wall) have malrotation.
Diagnosis of GI malrotation may be confirmed with abdominal radiographs, ultrasound, CT, and fluoroscopy. Emergency surgical treatment is required in cases where volvulus (twisting) and/ or obstruction accompanies GI malrotation. Patients should not be fed orally to avoid exacerbating the situation. Instead, a feeding tube through the nose or mouth is used, while electrolyte and fluid balances are maintained.
Shock, if present, is treated with vasopressive agents to correct low blood pressure, appropriate fluid resuscitation and blood products, if applicable. Surgery is done by means of the Ladd procedure. This procedure entails an appendectomy, dividing Ladd’s bands (tissue connecting the cecum to the abdominal wall), proper placement of the small of the large intestines within the abdominal cavity and, if necessary, the treatment of volvulus.