Paediatrics: Midgut malrotation and volvulus

Midgut malrotation and volvulus

During the first trimester of intrauterine development the foetal midgut transiently herniates into the umbilical cord. As this reduces, the mesentery normally rotates to bring the cae-cum to lie in the right iliac fossa and duodenojejunal flexure (DJF) to lie to the left of the midline. The midgut mesentery thus extends diagonally across the back of the abdominal cavity and provides a broad stable pedi-cle for the SMA to supply the bowel. Malrotation is a failure of this normal rotation that leaves the caecum high in the right upper quadrant and DJF mobile in midline. The result is a narrow base for the midgut mesentery and a narrow mobile pedicle through which the SMA runs. Malrotation is usually asymptomatic and only detected by contrast meal and follow through.

Midgut malrotation

•   Midgut malrotation predisposes to midgut volvulus.

•   To prevent this complication, surgical correction of a malrotation is advised using Ladd’s procedure.

•   An incidental appendicectomy is usually performed.

Midgut volvulus

•   This is a catastrophic event that occurs without warning.

·  The immediate effect is high intestinal obstruction at duodenal level that is rapidly followed by infarction of the entire midgut.

Symptoms

•   Bile-stained vomiting.

•   Circulatory collapse.

•   Tender abdomen.

Diagnosis

•   AXR (Fig. 23.10). May appear similar to duodenal atresia with a ‘double bubble’ and a paucity of gas elsewhere in the abdomen.

•   The diagnosis is confirmed by an urgent (even middle of the night) upper GI contrast study.

Surgical treatment

•   Immediate laparotomy to untwist the volvulus.

•   If the bowel is healthy a Ladd’s procedure is performed.

If bowel viability is doubtful a second look laparotomy may be necessary after 24hr. Frequently, there is massive intestinal necrosis and the child is left with a very short gut in which case long-term IV feeding is required.