Uterus, prolapsed: A uterus that has moved from its normal position in the abdominal cavity into a different position, usually a lower position. Prolapsed uterus may occur because of underlying weak muscles or simply as a result of repeated term pregnancies. It can sometimes interfere with conception, cause difficulties during pregnancy, and contribute to pelvic pain. A prolapsed uterus can be treated by inserting a stabilizing device into the vagina called a pessary. Sometimes surgery is required.