Placenta accreta. A clinicopathologic review of 67 cases

During a 20-year period 67 uteri removed from placenta accreta, among a population of 645,000 live births and stillbirths in Northern Ireland, were examined. Of the 37 involving the cavity, only 31 were placenta accreta vera; 14 of these were total and 17 partial. Three others showed invasion into the wall (placenta increta), and three penetration through the wall (placenta percreta). When any part of the placental adhesion involved the previa site the case was taken to be a placenta previa accreta; here adhesion was extensive in 10 and limited in 7. A further 11 were examples of placenta previa increta, and 2 more of placenta previa percreta. There were only two maternal deaths. These variants are described and illustrated, and the association with high parity and, especially in the previa cases, with previous cesarean section is emphasized. The histologic deficiency of maternal decidua at the implantation site and the recognition and behavior of cells of the nonvillous trophoblast are briefly described. Hysterectomy, which in placenta previa variants must be adequate to excise the area of cervical involvement, appears to be the rational treatment.