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Intestinal obstruction is a common surgical emergency. It is often due to adhesions; however, when the patient is young and has a virgin abdomen, we have to consider uncommon causes. We present a rare case of reversed rotation of the midgut as a cause for intestinal obstruction.
A 25-year-old man presented via accident and emergency with pain in the left upper quadrant for 4 days. He had constipation for 3 days which progressed to absolute constipation. This was associated with increasing abdominal distension and vomiting of at least 10–15 times a day. He was known to have Gilbert’s syndrome, depression and hay fever and had had no previous abdominal surgery. He was a smoker and used to drink alcohol moderately.
On examination, he was apyrexial and haemodynamically stable. His abdomen was distended but non-tender, with increased bowel sounds. No hernias and digital rectal examination revealed an empty rectum with no other abnormalities. Full blood count revealed leucocytosis of WCC 14.2 × 109 cells/l.
Plain abdominal X-ray showed dilated loops of small bowel which were pushed to the right side of the abdomen (Fig. 1). Chest X-ray revealed no abnormalities.
He was treated conservatively overnight and re-assessed in the morning when a Gastrograffin follow through was obtained. This showed contrast in the stomach and the duodenum. The pyloric region of the stomach was displaced upward by a significantly enlarged, distended segment of large bowel (Fig. 2). The appearances were likely to represent a caecal volvulus. The rest of the contrast was vomited back. The decision was made to undertake an urgent exploratory laparotomy.
Findings at laparotomy were of a caecal volvulus with ischaemia and serosal tears. Reversed rotation of midgut loop, through 90º in a clockwise direction. The transverse colon was seen to cross behind the superior mesenteric vessels (SMVs); the duodenum crosses in front of them; otherwise the disposition of the viscera appeared to be normal. The root of the mesentery of the small intestine (pre-arterial) has acquired its usual secondary attachment to the posterior abdominal wall, except where it crosses the transverse colon (Fig. 3). At this point, narrow tunnel has been left for the passage of the transverse colon.1 With theses operative findings, reversed midgut rotation was confirmed as a cause for the acute intestinal obstruction.
The right colon was mobilised to the hepatic flexure where the proximal transverse colon was found to be constricted and fixed to the posterior abdominal wall, lying posterior to the duodenum and SMV. The duodenum was kocherised. To avoid injury to the superior mesenteric vessels, the transverse colon was divided to the left of the vascular pedicle and pulled through with blunt dissection. Similarly, the ileum was divided just proximal to the ileocaecal valve, and a fromal right hemicolectomy was performed.
A side-to-side anastomosis anterior to the duodenum and SMV was performed. No drain was required and the patient had an uneventful postoperative recovery.
First described in the late 1800s, reversed rotation occurs when the midgut loop erroneously rotates in a clockwise direction.4 As a result, the duodenum and the transverse colon are reversed in position; the transverse colon lie posterior to the superior mesenteric artery and the duodenum lies anterior.
Reversed rotation occurs when the postarterial segment of the midgut returns to the abdomen first. The caecum begins its migration and passes to the right behind the superior mesenteric artery. This reversed migration unwinds the normal counter-clockwise rotation that occurred during the first stage and substitutes a final clockwise rotation of 90º, so that the transverse colon lies behind the duodenum and is separated from it by the superior mesenteric artery.5
Clinical diagnosis of reversed rotation is not possible, but suspicion of midgut malrotation may be raised by the presenting symptoms and signs. The reversed rotation may lead to volvulus of the mobile right colon or the entire midgut, stenosis of the transverse colon because of pressure on it in the retro-arterial tunnel, or obstruction at the duodenojejunal junction because of pressure of Ladd’s bands or volvulus. In the neonate and infant, it presents as acute intestinal obstruction necessitating immediate surgical attention;6 in the adult, intermittent subsiding bouts of bowel obstruction, coming to definitive surgical care only after several episodes, are more common.7
As this case demonstrates, the incidence of malrotation should not be forgotten during laparotomy in the young to ensure prompt treatment to prevent rupture of the bowel and life-threatening complications.