Placenta accreta: mild cases diagnosed by placental examination

We describe 36 placentas in which microscopic foci of myometrial tissue were adherent to the basal plate with deficient intervening decidua, consistent with a mild or focal form of placenta accreta. In only four cases was a diagnosis of placenta accreta considered clinically, and none of the cases resulted in hysterectomy. Twenty-one of the mothers underwent cesarean section for the current pregnancy, with 10 of the mothers having a history of previous cesarean section. The placenta failed to separate spontaneously in eight of the 15 vaginal deliveries necessitating manual removal of the placenta. Additional maternal factors included multiparity in 33, placenta previa in two, leiomyomas in two, and previous spontaneous abortion or voluntary interruption of pregnancy in 23. Four cases were complicated by retained placental fragments and three by postpartum hemorrhage. We conclude that these milder cases of placenta accreta are frequently associated with previous uterine operations and multiparity, and although not uncommon, are frequently not clinically suspected. Placental examination is useful in making the diagnosis of placenta accreta in cases not requiring hysterectomy, particularly if the basal plate is well sampled.