The Role of Magnetic Resonance Imaging to Rule Out Suspected Appendicitis in Pregnant Women

Introduction: Pregnant women with acute abdominal pain pose a diagnostic challenge. Delay in diagnosis may result in significant risk to the fetus. The preferred diagnostic modality is magnetic resonance imaging (MRI), since ultrasonography (USG) is often inconclusive and computed tomography (CT) would expose the fetus to ionizing radiation. Study objectives were to describe the process in setting up an aroundthe-clock MRI service for diagnosing appendicitis in pregnant women and to evaluate the contribution of abdominal MR in the diagnosis of acute appendicitis. Material and Methods: We conducted a retrospective study of consecutive pregnant women presenting with acute abdominal pain over a 6 year period who underwent MRI studies. A workflow that involved a multidisciplinary team was developed. A modified MRI protocol adapted to pregnancy was formulated. Data regarding patients’ characteristics, imaging reports and outcome were collected retrospectively. Results: Forty-nine pregnant women with suspected appendicitis were enrolled. Physical examination was followed by ultrasound: when positive, the patients were referred for MR scan or surgery treatment; when the ultrasound was inconclusive, MR scan was performed. In 88% of women appendicitis was ruled out and surgery was prevented with fetus safer drugs. MRI diagnosed all cases with acute appendicitis and one case was inconclusive. The overall statistical performance of the study shows a negative predictive value of 100% (95%CI 91.9–100%) and positive predictive value of 83.3% (95%CI 35.9–99.6%). Conclusions: It provides a safe way to rule out appendicitis and to avoid futile surgery in pregnant women.