Midgut volvulus is a complication of malrotation in which clockwise twisting of the bowel around the SMA axis occurs because of the narrowed mesenteric attachment. This life-threatening condition is a clear indication for emergent surgery. The clinical diagnosis of midgut volvulus in older children and adolescents is difficult because the presentation is usually nonspecific and malrotation is rarely considered. Recurrent episodes of colicky abdominal pain with vomiting over a period of months or years are typical and may eventually lead to imaging. Diarrhea and malabsorption from chronic venous and lymphatic obstruction may also occur (Berdon 1995). Findings on abdominal radiographs in midgut volvulus are usually abnormal but nonspecific. Upper gastrointestinal examination (the study of choice in neonates) shows the typical corkscrew appearance of the proximal small bowel. However, in older patients with acute symptoms, US or CT are generally performed instead of a barium examination. Sonographically, an abnormal location of the mesenteric vein to the left or anterior to the corresponding artery can raise the suspicion of malrotation. When a volvulus occurs, twisting of the bowel loops around the mesenteric artery axis leads to the whirlpool sign (PRacROS 1992), best shown in Doppler color studies (PatiNO
Fig. 1.69a,b. Paralytic ileus due to gastroenteritis. a Supine film shows generalized dilated bowel loops and distal gas. b Upright film demonstrates multiple air-fluid levels
Fig. 1.69a,b. Paralytic ileus due to gastroenteritis. a Supine film shows generalized dilated bowel loops and distal gas. b Upright film demonstrates multiple air-fluid levels a
b and Munden 2004) (Fig. 1.13). In the last step of the process, the presence of free fluid and wall thickening may indicate vascular compromise. A similar appearance can be seen on CT (Bernstein and Russ 1998; Pickhardt and Bhalla 2002). Additional CT findings include duodenal obstruction, congestion of the mesenteric vasculature, and evidence of underlying malrotation. The presence of intestinal ischemia or necrosis is an ominous sign. Internal hernia caused by abnormal peritoneal bands is an under-recognized complication of malrotation after childhood (Maxson et al. 1995). This condition may also be life-threatening because of the risk of bowel obstruction and strangulation. CT findings of malrotation and small-bowel obstruction (without volvulus) may be seen in patients with this complication (Pickhardt and Bhalla 2002). Evidence of ischemic bowel again portends a poor prognosis. Some patients may present with a combination of midgut volvulus and internal hernia. These life-threatening events in adolescents who may be otherwise healthy underscore the importance of earlier detection and treatment.
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