What is the cause of placental abruption?

Placental abruption is a very serious complication in late pregnancy. It develops very quickly, and if not handled properly it can be life-threatening to both the fetus and the pregnant woman. Its incidence rate in our country is between one and two percent. So what causes it?

1. Vascular disease in pregnant women

Hypertensive disorders complicating pregnancy, especially in pregnant women with severe preeclampsia, chronic hypertension, chronic kidney disease or systemic vascular disease, are mainly caused by spasm or sclerosis of the spiral arterioles of the basal decidua, which leads to degeneration and necrosis of the distal capillaries and even rupture and bleeding. Blood forms retroplacental hematoma between the basal decidua layer and the placenta, causing separation of the placenta from the uterine wall. In the late pregnancy or after delivery, if the pregnant woman lies in the supine position for a long time, the pregnant uterus will compress the inferior vena cava, reducing the amount of blood returning to the heart, causing a drop in blood pressure, congestion in the uterine veins, a sudden increase in venous pressure, congestion or rupture of the decidual venous bed, formation of a retroplacental hematoma, and leading to partial or complete placental detachment.

2. Sudden decrease in intrauterine pressure

Premature rupture of membranes before full term; during delivery of twin pregnancies, the first fetus is delivered too quickly; when there is too much amniotic fluid, the amniotic fluid flows out too quickly after artificial rupture of the membranes, the pressure in the uterine cavity drops suddenly, the uterus contracts suddenly, and the placenta is dislocated and detached from the uterine wall.

3. Mechanical factors

Traumatic injury, especially direct impact or compression of the abdomen; when the umbilical cord is too short (<30cm) or is relatively short around the neck or body, the fetus descends and pulls on the umbilical cord during delivery; during amniocentesis, the blood vessels at the anterior wall of the placenta are punctured, and retroplacental hematoma is formed, causing placental detachment.

4. Other high-risk factors

Such as older pregnant women, multiparous women, smoking, cocaine abuse, metabolic abnormalities in pregnant women, pregnant women with a tendency to thrombosis, uterine fibroids, etc. Pregnant women with a history of placental abruption have a 10-fold higher risk of having another abruption than those without a history of placental abruption.