The best questions often stem from the inquisitive learner. As educators, we love—and are always humbled—by those moments when we get to say “I don’t know.” For some of these questions, you may already know the answers. For others, you may never have thought to ask the question. For all, questions, comments, concerns, and critiques are encouraged. Welcome to the Kids Korner.

What Is the Sensitivity of Ultrasound for Detecting Volvulus in Infants When Compared to An Upper GI Study?

Most of us do not work in a location that has ready access to obtain an upper GI study in infants to evaluate for malrotation with midgut volvulus. While surgical evaluation is the true gold standard for identifying midgut volvulus, the diagnostic study of choice for many surgeons tends to be the upper GI study. But what about ultrasound? In cases where the clinical suspicion is lower for a midgut volvulus, but you feel it still needs to be explored, can ultrasound help?

Interestingly, upper GI studies have a wide range of sensitivities and specificities for diagnosing malrotation with midgut volvulus. The sensitivity for the diagnosis of malrotation, alone, ranges from 40-100 percent.^1,2 The diagnosis of malrotation with midgut volvulus is lower.²

Regarding ultrasound’s ability to diagnose malrotation, a prospective study by Zhou et al included 70 children with suspected malrotation with ages ranging from 2 days to 13 years (median 31 days).¹ These children with suspected malrotation were included based upon their clinical exams and had symptoms of bilious vomiting, repeated upper abdominal pain with vomiting, or upper abdominal distention. Of these 70 children, 23 were confirmed to have malrotation by surgery. Regarding these 23 patients with malrotation, all 23 patients were found to have inversion of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) and 22 had the ultrasound “whirlpool” sign. Thirteen of the 23 children were noted to have a transverse duodenum in front of the mesenteric artery. The transverse duodenum should be behind the superior mesenteric artery and the “whirlpool” sign—which is indicative of volvulus—occurs when bowel rotates around its mesentery leading to whirls of mesenteric vessels. All cases of malrotation demonstrated inversion of the SMA and SMV and there was a single false positive, yielding a sensitivity and specificity of 100 percent and 97.6 percent, respectively. For the whirlpool sign, the sensitivity was 95.6 percent and specificity was 95.7 percent, respectively. These findings suggest that ultrasound is an excellent tool to evaluate for malrotation with volvulus.