A rare but potentially serious complication is that of uterine perforation. This may occur either during the device's insertion, or from its later embedment into the myometrium (uterine wall) and subsequent migration through to the intra-abdominal cavity. Perforation can cause internal scarring, infection, or damage to other organs, and may require surgery. Uterine perforation has been reported at rates ranging from 1 to 2.6 per 1000 insertions. It is believed that perforations are significantly underreported, however, and actual perforation rates are likely higher.