Unprovoked piriformis myositis presenting in a pregnant patient

A patient in her mid-30s presented to hospital at 25 weeks' gestation with acute onset of leg pain.Routine investigations were performed to rule out the common causes of leg and back pain in pregnancy, which were grossly normal. Piriformis pyomyositis was diagnosed on MRI and a collection was drained. Following an initial response to antibiotic therapy, the patient delivered by elective caesarean section, but the pain returned on postnatal day 2 and muscle inflammation was diagnosed again, requiring a repeat course of antibiotics.This case highlights a rare cause of leg pain in a pregnant patient, and the additional complexities of managing cases in the obstetric population.