What causes placental adhesion to the uterine wall?

Placental uterine adhesion is generally caused by conditions such as placenta previa, history of cesarean section, or prior myomectomy. Depending on the depth of placental villi invasion into the uterine muscle layer, it can be classified as follows: placental adhesion refers to placental villi attaching to the surface of the myometrium; placenta increta refers to placental villi invading into the uterine myometrial wall; and placenta percreta refers to placental villi penetrating through the uterine muscular layer and reaching or extending beyond the serosal surface of the uterus. Clinically, placenta accreta spectrum disorders may lead to severe postpartum hemorrhage and shock, sometimes necessitating hysterectomy to save the patient's life, and in severe cases, may even result in patient death.