OP10.01: Placenta accreta: risk factors, accuracy of antenatal diagnosis, and effect on pregnancy outcome

The aim of this study is to define the clinical risk factors for placenta accreta, determine whether the rate of placenta accreta is increasing in conjunction with the rising Cesarean section rate; evaluating the accuracy of antenatal ultrasound for diagnosis, and the effect of these on pregnancy outcome. The records of all patients who were delivered by Cesarean section (CS) followed by hysterectomy during the last eleven years (1993–2005) at the Mater Mothers' Hospital, Brisbane were reviewed. There were 65188 (1996–2005) deliveries at Mater Mothers Hospital Brisbane during the study period. A total of 40 (93–2005) cases had the histological diagnosis of abnormal placental attachment. Among these, 58% were placenta accreta, 21% were placenta increta and 21% were placenta percreta. The mean age of women with placenta accreta was 35 years, gravidity 9, parity 4.5, number of previous Cesarean deliveries 1.6 and number of previous curettage 1.07. Thirty one (77.5%) women with placenta accreta had coexisting placenta previa, 14 (35%) had at least 1 previous Cesarean section and 10 (25%) had at least one previous curettage. Three (7.5%) women were nulliparous. Thirty one patients had antenatal ultrasound done in MMH and twenty six (83.8%) of these were recognised antenatally by ultrasound to have abnormal placentation. Thirty seven women (92.5%) required blood transfusions. The incidence of placenta accreta has increased, probably explained by the increasing rate of Cesarean delivery. Ultrasound scan is reliable as a diagnostic tool for antenatal diagnosis of possible placenta accreta. Counselling of women undergoing Cesarean delivery should include the risk of abnormal placentation and its subsequent morbidities.