Purpose or Case Report: Rapid detection and accurate diagnosis of midgut volvulus are crucial due to the risk of bowel infarction with delayed diagnosis. The purpose of our study is to evaluate the diagnostic accuracy of abdominal ultrasound (US) for midgut volvulus in the clinical setting of multiple sonographers and radiologists.
Methods & Materials: A retrospective review of all abdominal US exams performed to evaluate for malrotation and midgut volvulus from January 2018 through September 2019 was performed. The abdominal US exams assessed the relationship between the superior mesenteric artery and vein (SMA/SMV), the presence of a whirlpool sign (swirling of the SMV around the SMA), and the position of the third portion of the duodenum. Demographics and clinical outcomes were obtained from the electronic medical record. Sensitivity and specificity of the whirlpool sign for midgut volvulus were determined. Reference standard for midgut volvulus was diagnosis at surgery. Or, if no surgery normal upper gastrointestinal (UGI) series or computed tomography (CT), or a minimum of 1-month clinical follow-up.
Results: 173 abdominal US exams for suspected midgut volvulus were performed by 35 sonographers and interpreted by 23 pediatric radiologists on 171 children (median age 38 days, range 0-6269; 52% male). Fifty US exams were excluded due to inadequate follow-up, leaving 123 for analysis. 33/123 (27%) were considered nondiagnostic due to bowel gas or other technical limitations, one in a patient with midgut volvulus. Although other findings on this patient's ultrasound indicated need for exploratory laparotomy and the exam was reported as such. For the 90 US exams considered diagnostic, the whirlpool sign had a sensitivity and specificity of 100% (8 true positives, 0 false positives, 82 true negatives, 0 false negatives).
Conclusions: Abdominal US demonstrates high accuracy for the diagnosis of midgut volvulus in the setting of multiple sonographers and interpreting radiologists when not technically limited. This provides evidence that US may serve as a first-line imaging exam for suspected midgut volvulus, with the UGI series reserved for inconclusive US exams. Larger multi-institutional studies are needed to more precisely characterize the test performance and generalizability of US for suspected midgut volvulus.