Abnormal placentation in which all or parts of the PLACENTA are attached directly to the MYOMETRIUM due to a complete or partial absence of DECIDUA. It is associated with POSTPARTUM HEMORRHAGE because of the failure of placental separation. | Invasion of CHORIONIC VILLI occurs through the MYOMETRIUM penetrating the uterine SEROSA. | Invasion of CHORIONIC VILLI occurs deep into the MYOMETRIUM. [MeSH]
