Teaching Case

A 4-day-old male infant, born at 40 weeks gestation, was admitted with bilious non-bloody vomiting. On examination, he had stable vital conditions and his abdomen was minimally distended.

Abdominal ultrasonography (US) with colour Doppler showed inversion of the position of the superior mesenteric vessels, with the superior mesenteric artery (SMA) on the right side of the superior mesenteric vein (SMV) (Fig. 1). There was also a heterogeneous epigastric mass, with a distinctive whirling pattern appearing as a clockwise winding of the small bowel around the SMV (Fig. 2). An abdominal radiograph revealed paucity of bowel gas distal to the duodenum (Fig. 3). Upper gastrointestinal imaging showed a dilated stomach and proximal duodenum with stagnation of contrast at the delayed phase (Fig. 4). The patient was taken to the operating room and laparotomy was performed, assessing the diagnosis of malrotation with midgut volvulus. The surgeon derotated the volvulus, separated the Ladd’s bands and returned the bowel to a position of non-rotation (caecum placed into the left lower quadrant and Treitz angle into the right upper quadrant).

Intestinal malrotation leading to midgut volvulus is a paediatric emergency. Malrotation is defined as an abnormal rotation of the duodenum and/or caecum around the SMA axis, with variable fixation of the midgut to the retroperitoneum [1]. Malrotation is a possible cause of volvulus of the midgut around its vascular axis. When the venous and arterial flow is impeded, midgut volvulus can result in massive bowel infarction, and death [1, 2]. Midgut volvulus may present with abdominal pain, distension, diarrhoea or constipation but the most common clinical finding is bilious vomiting [3]. Abdominal radiographs might suggest a duodenal obstruction, showing a dilated duodenum and a lack of gas distal to the duodenum [3, 4], but they can be interpreted as normal in 20% of cases [3]. Ultrasonography (US) with colour Doppler is a very useful diagnostic tool, determining the relationship between the superior mesenteric vessels. Normally, the SMA lies to the left of the SMV. Reversal of that position suggests malrotation [5]. US findings also include the “whirlpool” appearance of the mesentery around the SMA [5]. Upper gastrointestinal imaging (UGI) is often considered as the “gold standard” test to detect malrotation, showing a low duodeno-jejunal junction (DJJ), absence of the DJJ from its typical position to the left of the vertebral body pedicle, the jejunum located on the right, or a corkscrew appearance [5, 6]. The barium enema might show a malpositioned caecum in 80% of cases of malrotation, but is rarely used alone [5, 7]. Computed Tomography (CT) can also be useful to detect the reversal of the position of the superior mesenteric vessels and the “whirlpool sign” but it exposes the child to a significant dose of radiation [4] compared to US. When the diagnosis of malrotation with midgut volvulus is suspected, laparotomy should be performed quickly [8]. Surgical treatment, initially described by Ladd in 1936, includes derotation of the bowel with or without resection, division of Ladd’s bands, mobilization of the right colon and the duodenum, division of adhesions around the SMA, and appendectomy [9, 10].