WP7.1 - MRI for suspected acute appendicitis in pregnant females: What is the best imaging modality?

Abstract Introduction/Aims Acute appendicitis (AA) in pregnancy is the commonest non-obstetric cause of acute abdominal pain, but controversy surrounds the most appropriate imaging modality in this group. Ultrasound (USS) and Magnetic Resonance Imaging (MRI) have no known fetal risks. Hence, The World Society of Emergency Surgeons (WSES) recommends MRI in pregnant patients with suspected appendicitis, if available, but emphasises the preferred initial use of USS. This project explored the use of both imaging modalities in pregnant patients with suspected AA. Method Data was collected for all pregnant patients undergoing an MRI for suspected AA between 2015 and 2023. Results Of the 29 patients identified, the mean gestation was 23 weeks (range 2-36), and over half (15, 52%) of MRI scans were performed in 2022/3. Intra-abdominal pathology was seen in 17 (59%) patients, with 8 (47%) having MRI features of AA. 63% of those diagnosed with AA had an USS pre-MRI, and 40% identified the appendix as "normal." Other intra-abdominal pathologies picked up on MRI included pyelonephritis(1), small bowel obstruction(1), stercoral perforation(1), and ovarian torsion(2). Of the 8 patients with MRI-proven AA, all underwent appendicectomy: 3 laparoscopic, 2 open, and 3 with simultaneous Caesarean section, of whom 2 required ileocaecal resection. Conclusions Diagnosis of abdominal pain in pregnancy is a challenge. USS may be reasonably sensitive and specific in dedicated hands, but pathology may still be missed. In this patient group, for which appendicectomy for AA is associated with better outcomes than non-operative management, MRI should be obtained for accurate diagnosis.