Purpose or Case Report: Midgut malrotation can lead to significant morbidity and even mortality if complicated by volvulus or obstruction related to Ladd bands. At our institution, it is routine practice to perform fluoroscopic upper gastrointestinal (UGI) exams to assess for intestinal malrotation prior to gastrostomy tube placement. We sought to determine if it is feasible to assess midgut rotation using any previous MRI exams that include the upper abdomen. We hope to remove the need for upper GI exams in patients with previous MRI exams, thus preventing unnecessary radiation exposure and overutilization of resources, prior to gastrostomy tube placement.
Methods & Materials: With IRB wavier of consent, a retrospective study was performed on pediatric patients with MRI examination before fluoroscopic UGI exams from 2011-2021. Exclusion criteria include insufficient image quality and/or coverage. Midgut rotation on MRI was assessed by three blinded pediatric radiologists. For midgut rotation to be designated as normal, the course of the third portion of the duodenum had to be identified between the aorta and SMA, and the SMV to the right of the SMA-aorta axis. Inter-rater reliability was measured with Kappa analysis. Sensitivity analysis was performed using fluoroscopic UGI findings as the gold standard.
Results: Nineteen patients ages 1 day to 11 years were included in our study and two patients were excluded because of inconclusive UGI exam. All remaining seventeen patients had normal rotation on MRI with strong interobserver agreement (Kappa 0.86). One of the 17 conclusive UGI exams was reported as positive for malrotation, although intraoperative findings were negative for malrotation and therefore in agreement with the MRI findings. Sensitivity analysis demonstrated MRI examination with 100% sensitivity and 99.9% negative predictive value for midgut malrotation.
Conclusions: MRI can be useful in ruling out malrotation and obviating fluoroscopic UGI exams prior to gastrostomy tube placement.