Retained placenta is defined as failure of placental delivery within 30 minutes after birth of the baby. It occurs in about 1% of deliveries. Causes include uterine atony, a constriction ring in the uterus, or abnormal adherence of the placenta. Clinical signs include bleeding if the placenta is partially separated, a lax uterus, and examination may reveal a constriction ring or abnormal placental adherence. Management depends on the cause, and may include medications to induce uterine contractions, manual separation, or in severe cases of adherence, hysterectomy. Complications can include shock, hemorrhage, or infection.