Making the diagnosis of midgut volvulus: Limited abdominal ultrasound has changed our clinical practice.

PURPOSE: To assess the diagnostic accuracy of limited abdominal ultrasound (US) examination for midgut volvulus (MGV) and to evaluate how clinical practice has changed in a free-standing children's hospital leading to the near obsolescence of upper GI (UGI) studies for the diagnosis of MGV.

MATERIALS AND METHODS: All patients with suspected MGV who underwent abdominal US during 2016-2017 were identified using keyword search tools in the radiology information system. Retrospective, blinded image review was performed by a certificate of added qualification (CAQ), board certified pediatric radiologist. US images were evaluated for the presence of the superior mesenteric artery (SMA) cutoff sign and twisting of the bowel and mesentery around the SMA (whirlpool sign). The results were compared with the operative reports.

RESULTS: 195 US studies were performed from 2016 to 2017. The most common presentations were vomiting (44%), abdominal pain (7%), and suspected malrotation (10%) 195 US studies were reviewed, of which 16 were nondiagnostic. The remaining 179 diagnostic studies showed MGV in 14 patients. Those 14 patients were surgically explored and confirmed to have midgut volvulus. 7 of the 16 nondiagnostic US studies were further evaluated with UGI examination with 1 patient demonstrating malrotation without volvulus, which was confirmed at surgery. 2 had CT exams which were normal. 4 were followed clinically. The remaining 3 patients went to surgery, all of which did not show MGV. There were 164 negative US, none of whom went to surgery. US was diagnostic in 92% of patients and when diagnostic the positive and negative predictive values of US were 100%.

CONCLUSION: Limited abdominal US is a highly accurate examination for the diagnosis of midgut volvulus. UGI exposes patients to ionizing radiation and should be reserved for patients in whom US is nondiagnostic or inconclusive.

TYPE OF STUDY: Retrospective review.

LEVEL OF EVIDENCE: Level 3.