What are the symptoms of placenta implantation?

Placenta accreta refers to a group of diseases in which placental tissue invades the myometrium to varying degrees, including placental adhesion, placenta accreta, and placenta penetrability. Under normal circumstances, the placenta can be detached from the uterine wall after delivery, but if there is placenta accreta, some or all of the placenta remains attached to the uterine wall after delivery, which may cause severe postpartum hemorrhage and even shock, which is a critical obstetric complication.