Acute appendicitis and pregnancy: diagnostic performance of magnetic resonance imaging.

Background: The aim of this study was to evaluate the performance of magnetic resonance imaging (MRI) in the diagnosis of acute appendicitis in pregnant women.

Methods: The study was conducted in 2 referral centers in Brussels, Belgium, between March 1st 2009 and January 31st 2017. Pregnant women who presented with abdominal pain and underwent MRI were included. Baseline characteristics, clinical, laboratory, and ultrasound test results were extracted retrospectively from the electronic medical charts. MRI exams were prospectively reevaluated by an experienced radiologist blinded to patient outcome and MRI findings. Visualization of the appendix and assessment of gastrointestinal, genitourinary, and vascular systems were recorded. The diagnosis of acute appendicitis was confirmed by pathology exam.

Results: In total, 85 patients were included. The appendix was identified in all patients on MRI and acute appendicitis was suspected in 7. The diagnosis was confirmed in 6 patients. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI were 100% (95% confidence interval [95% CI]: 54.1%-100%), 98.7% (95% CI: 93.2-99.9%), 85.7% (95% CI: 46.1-97.7%), and 100%, respectively. In contrast, the sensitivity, specificity, PPV, and NPV of the combination of clinical exam, laboratory findings and/or ultrasound were 100% (95% CI: 54.1%-100%), 62% (95% CI: 50.4-72.7%), 16.7% (95% CI: 13.1-20.96%), and 100%, respectively.

Conclusion: MRI is reliable in confirming or excluding acute appendicitis during pregnancy, with a rate of visualization of the appendix approaching 100%. Efforts should be focused on the implementation of MRI as a first-line imaging exam in the workup of suspected acute appendicitis during pregnancy.