Perforation of the uterus by an intrauterine device usually occurs at the time of insertion. However, silent migration by such a device is a well recognized complication. In the case described here, sciatic irritation was caused by an intrauterine device that had penetrated the uterine wall and migrated to the vicinity of the first sacral nerve roots though remaining intrapelvic and intraperitoneal. The proximity of the lumbosacral plexus to the uterus is shown. A freely movable intrauterine device that has not been trapped in the uterine wall or by the omentum can migrate posteriorly to the area of the lumbosacral nerve roots. The left lumbosacral plexus is less susceptible to this complication because it is partially shielded by the sigmoid colon. Since the device may migrate to different parts of the pelvis, symptoms may vary.
