Abdominal imagingCase Type
Dr. Niharika Prasad, Dr. Sanjay M. KhaladkarPatient
44 years, male
A 44-year male presented with few episodes of non-bilious vomiting since one week. It was accompanied by chest pain and breathlessness. He consumed alcohol weekly on a regular basis. There was no history of altered bowel habits, fever, weight loss or hemoptysis. There was no trauma or surgery in the past. General clinical examination was normal.
On admission, the patient was subjected to Ultrasonography of the abdomen which revealed a grossly distended stomach and proximal duodenum. Jejunal loops were on the right side of the abdomen. There was no abnormal wall thickening, mass lesion or ascites. Following this, a computed tomography (CT) with oral & intravenous contrast was performed. Above mentioned findings were confirmed. In addition, there was abrupt narrowing at the junction of 2nd and 3rd part of the duodenum due to an incomplete annular pancreas. Duodenal- jejunal junction was in the midline.
The relation between superior mesenteric artery (SMA) and superior mesenteric vein (SMV) was normal at the root of the mesentery; however, a reversal was seen more distally. There was counterclockwise twisting of mesenteric vessels and small bowel loops, suggestive of a volvulus. Ileo-caecal junction and caecum were normal in position. Aorto-mesenteric angle measured 24.8 degrees (Normal range 28-65 degrees). There were no features of small bowel ischemia. These findings were suggestive of a partial malrotation with small bowel volvulus. Duodenal obstruction was due to incomplete annular pancreas. Duodenal obstruction and SMA syndrome were found intra operatively. Duodenojejunostomy was performed and the patient was scheduled for follow up.
Intestinal malrotation can be symptomatic or asymptomatic and can present at any age, although most commonly, it occurs in the first month of life. In adults, the presenting symptoms are usually non-specific. It is due to any deviation from the 270 degrees clockwise rotation of the midgut during normal embryological development. The commonest types include ‘incomplete’ rotation- anomalies involving the duodenum or the right colon and ‘non-rotation’, more common in the adult population.  A shortened mesentery is a predisposing factor.
Radiologists have an important role to play in diagnosis and missing this condition can lead to life-threatening complications like bowel ischemia, volvulus, perforation and gangrene. The rotation of gut occurs in three stages- I) between 5-10 weeks: herniation of midgut, 90 degrees counter-clockwise rotation and return to abdomen II) 11th week: further rotation till 270 degrees resulting in anterior position of the transverse colon and III) fixing of the mesentery. 
Ladd’s bands are fibrous adhesions which fix caecum and ascending colon to the abdominal wall. These can cause compression of the second part of duodenum. In this case, the duodenal obstruction resulted from an incomplete annular pancreas. The ‘whirlpool sign’ on CT has been described as wrapping of the SMA by coils of bowel and mesentery with the SMV, resulting in the appearance of concentric circles.  In pediatric age group, upper gastrointestinal (GI) contrast study with water-soluble agent forms an initial standard investigation of choice while CT is confirmatory. Patients with malrotation will have a duodenal jejunal flexure to the right side. On upper GI series, a ‘corkscrew pattern’ of twisted proximal intestine is characteristic of volvulus.  Emergency or elective Ladd’s procedure is the most commonly performed surgery. Laparoscopic management has an emerging role in the management of this condition. 
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