272: Risk factors for placenta previa-accreta from a prior delivery: A pilot study

Abstract

STUDY CHAVI KARKOWSKY, HILLARY KEENAN, B. SCOTT SEGAL, DANIELA CARUSI, Brigham and Women’s Hospital, Department of Obstetrics and Gynecology, Boston, Massachusetts, Brigham and Women’s Hospital, CCI Biostatistical Consulting Service, Boston, Massachusetts, Brigham and Women’s Hospital, Department of Anesthesiology, Perioperative and Pain Medicine, Boston, Massachusetts OBJECTIVE: A placenta previa in the setting of a prior uterine incision is the strongest risk factor for placenta accreta. However, no studies have examined how the environment in which that incision is created can affect the risk of developing a placenta previa-accreta. We undertook this study to evaluate the association of placenta previa-accreta after prior cesarean with characteristics of the prior delivery. STUDY DESIGN: We conducted a retrospective cohort study over a 12-year period at a single institution. The cohort consisted of all women undergoing delivery for a placenta previa who had one prior cesarean, and whose one prior cesarean was at the same institution. Our outcome variable was pathologic or clinical diagnosis of placenta accreta. Medical records were reviewed for details of the prior delivery, including whether the patient labored and presence of fever. Demographic details were also collected. The variables were analyzed in a logistic regression model. Power analysis showed that we would need 450 patients in order to reach 80% power at a 95% confidence level. RESULTS: There were 75 subjects who met eligibility criteria over the 12-year period; 19% of these were diagnosed with placenta previa-accreta. No association was found between demographic variables and the presence of accreta. Subjects with a placenta accreta were twice as likely to have labored prior to their first cesarean section (odds ratio 2.1, 95% CI 0.7 7.0) though the study was insufficiently powered to find a significant result. The odds ratio for fever at prior cesarean section was 1.2 (95% CI 0.3 5.3). CONCLUSION: In this pilot study, we found a trend towards placenta previaaccreta at repeat cesarean section when the patient had labored at the primary cesarean delivery. A larger study is warranted to confirm this association, as it may aid patient counseling and prediction of this serious outcome