Prediction of Placenta Accreta Spectrum by Prenatal Ultrasound Staging System in Women with Placenta Previa with Scarred Uterus

Background Placenta accreta spectrum (PAS) disorders are defined as range of pathological adherence/invasion of placenta. Prenatal diagnosis of PAS disorders using ultrasound doppler can optimize fetomaternal outcome and reduce complications. Objectives To study the predictive value of prenatal ultrasound staging system for the presence and severity of placenta accreta spectrum and its correlation with fetomaternal outcomes. Method This was a prospective cohort study conducted in Obstetrics and Gynecology department at VMMC and Safdarjung Hospital, New Delhi, over a period of 18 months. It included 50 women with singleton pregnancy > 28 weeks with placenta previa with scarred uterus after taking informed consent and ethics committee approval. All the women underwent ultrasound and PAS score was assigned, which was correlated with intraoperative FIGO grade, histopathology and fetomaternal outcomes. Results In 50 women enrolled, prenatal ultrasound staging was performed and PAS score 0, 1, 2 and 3 was assigned. Cesarean hysterectomy was required in all 21(42%) women with PAS score > 0 (PAS 1, 2, 3). Intraoperative, focal and complete invasion was seen in 4% and 38%, respectively, and FIGO grade 1, 2, 3, 4, 5 and 6 was observed in 46%, 16%, 30%, 0%, 6% and 2%, respectively. On histopathology, 14.28% (3/21) with PAS > 0 did not have any invasion, while 85.71% (18/21) had invasion, i.e., accreta, increta and percreta in 57.14%, 19.05% and 9.52%, respectively. Considering histopathology as gold standard, the overall sensitivity, specificity, PPV, NPV and diagnostic accuracy of PAS score were 100%, 90.62%, 85.71%, 100% and 94%, respectively. Conclusion Prenatal ultrasound staging system is a simple and feasible screening modality. Hence, it should be used in all high-risk women with placenta previa and scarred uterus for definitive prenatal diagnosis of PAS.