Caesarean section defects may contribute to irregular menstrual bleeding. We performed a prospective audit of 300 women referred to our unit for pelvic scans, aged between 20-45years, during the period October 2007 –May 2008. The women completed a questionnaire to determine the history of caesarean section and irregular bleeding. During the pelvic ultrasound examination, if a caesarean section scar defect was noted, images of the size were recorded. A review of the indications for the scans, a history of irregular bleeding and any other relevant pathology detected on gynae scans was recorded. A total of 300 pelvic scans were assessed. 80 women had a history of caesarean sections, and 27 of these had a visible uterine defect. 20 had a measurable scar defect in the absence of any other uterine pathology.13 of these women also reported prolonged periods or intermenstrual bleeding. Caesarean section scar defect may be the cause of menstrual abnormalities, particularly intermenstrual or post menstrual spotting.