MRI remains highly accurate in the diagnosis of appendicitis in pregnancy when read by radiologists of mixed specialty training and experience.

Abstract

To audit the accuracy of magnetic resonance imaging (MRI) abdominal studies performed in the diagnosis of appendicitis in pregnant patients when read by radiologists of mixed experience. MRI reports from 45 pregnant women presenting to our emergency department for the investigation of appendicitis between 2009 and 2020 were retrospectively reviewed. Where available, these reports were correlated with surgical and pathology reports as well as follow-up clinical information. Following a review of literature, accuracy targets were set. Statistical analyses including sensitivity, specificity, positive, and negative predictive values were calculated. A total of 18 radiology consultants read 45 MRI abdominal studies in the assessment of appendicitis during pregnancy with 62% (n = 28) of these read by specialist radiologists and the remainder by general radiologists. This yielded an accuracy in diagnosis of 99.8%, sensitivity of 80% (95% CI: 49-94.3%), and specificity of 100% (95% CI: 90-100%). The calculated negative predictive value was 94.6% (95% CI: 82.3-98.5%), and positive predictive value was 100% (95% CI: 90-100%). The appendix was not identified in 19 patients (42%). A statistically significant relationship between the presence of right iliac fossa stranding of the fat OR free fluid was associated with appendicitis (p = 0.01). Alternate diagnoses were identified in 8% (n = 4) of cases. MRI is a highly accurate imaging modality for the assessment of appendicitis in pregnancy. Even with variable reader MRI experience, MRI demonstrates an accuracy of 99.8% and a positive predictive value for acute appendicitis of 100%. Double reading and the possible inclusion of DWI may help further improve accuracy and minimise false-negative rates.