Intestinal malrotation in an adult presenting as midgut volvulus

A 24-year-old male presented to the emergency department with a history of acute onset abdominal pain and bilious vomiting for 1 day. No history of previous abdominal surgery. No history of fever. No history of alcohol intake. On examination, tenderness was noted in the epigastric and umbilical region. The patient was subjected to multimodality imaging.

The erect X-ray abdomen revealed two air-fluid levels (double bubble): a large bubble representing the stomach and a small bubble representing a distended duodenum. There is no evidence of air under the diaphragm (Figure 1).

Ultrasound of the upper abdomen revealed a well-distended stomach with whirling of vessels and small bowel loops (whirlpool sign) in the transverse plane in the right periumbilical region (Figure 2).

CT (computerised tomography) abdomen reveals a distended stomach and proximal duodenum with negative oral contrast (Figure 3), and a clockwise swirling of distal duodenum, proximal jejunal loops and their mesentery around the superior mesenteric artery axis (Figure 4). The duodenojejunal junction is located to the right of the midline, with the ileocaecal junction in the right lumbar quadrant adjacent to the duodenojejunal junction (Figure 5). There is an inversion of the superior mesenteric artery and superior mesenteric vein relationship, indicating malrotation (Figure 6).

The volume-rendered three-dimensional reconstruction imaging revealed the corkscrew appearance of the left branch of the superior mesenteric artery (the barber pole sign) (Figure 7).

The diagnosis of midgut volvulus secondary to intestinal malrotation was made. The patient underwent immediate surgery with uneventful post-operative recovery.

During the 5th and 12th weeks of embryological development, physiological intestinal herniation and rotation occur along the axis of the superior mesenteric artery (SMA) in a counter-clockwise direction for 270°. Failure of this process results in varying degrees of malrotation. Malrotation results in malpo­sition of the bowel and malfixation of the mesentery, resulting in a narrow mesenteric pedicle, which predisposes to volvulus [1].

Malrotation with midgut volvulus most commonly presents in infants. It is an extremely rare anomaly in adults accounting for only 15%. Midgut volvulus occurs secondary to intestinal malrotation with narrow mesentery. In adults with malrotation, midgut volvulus is the most common cause of small bowel obstruction [2].

Pa­tients with malrotation may be asymptomatic, which is incidentally detected during imaging or abdominal surgery. Acute symptomatic patients present with severe abdominal pain, distension and vomiting secondary to obstruction by midgut volvulus or Ladd’s band, causing external compression on the duodenum and jejunum. Chronic unexplained vague abdominal discomfort and abdominal pain can occur secondary to Ladd’s bands causing intermittent obstruction or volvulus. Abnormal peritoneal attachments, from the right lateral abdominal wall and liver to the caecum, are called Ladd’s bands [3].

Ultrasound, CT and barium meal are the main imaging modalities for diagnosis with specific imaging features.

In malrotation, the duodenojejunal junction is located to the right of the midline, with an abnormal mesenteric vessel relationship, and the superior mesenteric artery located to the right of the superior mesenteric vein. The imaging features of the midgut volvulus are pathognomonic, showing the typical “whirlpool sign” of the mesentery and the small bowel wrapped around the SMA in both ultrasound and CT. The tapering of an obstructed proximal small bowel gives a beak sign appearance. Barium meal study shows the typical corkscrew appearance of twisted small bowel loops. CT angiography also shows the typical corkscrew appearance of whirling SMA and its branches (the barber pole sign) [4].

The mainstay of treatment in acutely symptomatic patients is surgery by Ladd’s procedure. The procedure includes detorsion of the volvulus, Ladd’s band division, broadening of mesentery and division of adhesions around the SMA. If untreated, there are high chances of ischemia and necrosis of the bowel supplied by the SMA [5].