Content area
Full Text
Gastrointestinal (GI) complaints re among the most frequent auses for emergency department visits in the pediatric population. Radiology plays an ever-increasing role in the diagnosis and treatment of these emergencies. This article describes the clinical presentation, epidemiology, and imaging findings of 5 GI emergencies that require surgical intervention: Malrotation and midgut volvulus; intussusception; hypertrophic pyloric stenosis; appendicitis; and Meckel's diverticulum.
Malrotation and midgut volvulus
Malrotation is any deviation from the normal 270° counterclockwise rotation of the bowel that occurs during embryogenesis. The resultant shortened mesenteric pedicle predisposes to midgut volvulus, a clockwise rotation around the superior mesenteric artery axis that can lead to bowel ischemia. A mnemonic for remembering the direction of rotation of volvulus and surgical devolvulus is: "the surgeon turns back the hands of time."
The incidence of malrotation is 1 in 500.1 The male-to-female ratio is 2:1. Malrotation with midgut volvulus may become rapidly life-threatening. The previously healthy infant with bilious emesis is one of the few "drop everything else" presentations in pediatric imaging, as the stopwatch of ischemic bowel may be ticking. The older the child, however, the more atypical the symptoms; the teenager with chronic abdominal pain or malabsorption may be suffering from recurrent bouts of volvulus and devolvulus.
Conventional radiographs are neither sensitive nor specific for malrotation. On the upper GI series, it is crucial to locate the position of the duodenal-jejunal junction (DJJ). The DJJ must be at least over (but more reassuringly lateral to) the left vertebral pedicle and at the same height as the duodenal bulb on a well-centered view. If the DJJ does not meet these two criteria, then malrotation is diagnosed (Figure 1). Signs of midgut volvulus include an abrupt termination, or beak, of the contrast column (Figure 2) and the corkscrew (apple peel, or barber pole2) sign (Figure 3).
On ultrasound (US) and computed tomography (CT), the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) relationship may be reversed (Figure 4). Normally the SMV is to the right of the SMA; with malrotation, the SMV may occupy a position directly anterior or to the left of the SMA. Of critical importance, a normal SMA/SMV relationship does not exclude malrotation, and the upper GI remains the imaging gold standard. Conversely, some children...