After 20 weeks of gestation or during delivery, the placenta in its normal position is partially or completely detached from the uterine wall before the delivery of the fetus, which is called placental abruption. Placental abruption is a serious complication in late pregnancy, with rapid onset and progression, which can endanger the life of mother and child if not treated in time. The incidence of placental abruption is 4.6‰ to 21‰ in China and 5.1‰ to 23.3‰ in foreign countries. The incidence is related to whether the placenta is carefully examined after delivery. Some patients with mild placental abruption may have no obvious symptoms before delivery, and only during postpartum examination of the placenta, clot pressure is found at the abruptio, which is easily ignored. The abdominal examination shows that the uterus is hard like a plate on palpation and there is pressure pain, especially at the placenta attachment area. The diagnosis of placenta abruptio with a hard, plate-like uterus needs to be differentiated from the following diseases: 1. Placenta praevia: Mild placenta abruptio can also be painless vaginal bleeding, and the signs are not obvious, so the diagnosis can be confirmed by B-type ultrasonography to determine the lower edge of the placenta. The abdominal signs of placenta abruptio in the posterior wall of uterus are not obvious, so it is not easy to distinguish it from placenta praevia, and ultrasound examination can also identify it. The clinical manifestations of severe placenta abruptio are very typical and it is not difficult to distinguish it from placenta praevia. 2. Premature uterine rupture: It often occurs during labor, with strong contractions, lower abdominal pain and refusal to press, irritability, small amount of vaginal bleeding, and signs of fetal distress. The above clinical manifestations are difficult to distinguish from heavy placental abruption. However, most of the pre-ruptured uterus has a history of cephalopelvic disproportion, obstructed labor or cesarean delivery, and examination may reveal pathological uterine constriction ring, catheterization with meatus hematuria, etc., while placental abruption is often in patients with severe hyperemesis, and examination of the uterus is platelet-like hard.