Role of Color Doppler Ultrasound in Prediction of Adherent Placenta Previa

Introduction: Adherent placenta is a decidualisation disorder that includes placenta accreta, increta, and percreta.They are uncommon but potentially life-threatening conditions due to the risk of massive hemorrhage that may warrant hysterectomy.Risk factors include age, multiparity, previous uterine scar and placenta previa.Prediction of adherent placenta is possible using color Doppler ultrasonography.The aims of this study are to describe the pattern of adherent placenta among cases of placenta previa and to investigate diagnostic performance of abdominal ultrasound scanning and Doppler ultrasound in diagnosis of adherent placenta among placenta previa.Materials and methods: A prospective study over a 4-month period from August 2016 -November 2016 with institutional ethical approval was conducted in Benghazi Medical Centre, Libya.Ninety-one women with placenta previa complicated pregnancies, who had Doppler ultrasound at 36 weeks gestation, were included in the study.Results: Of 91 cases of placenta previa, 16.5% among them were adherent.Risk factors for adherent placenta in placenta previa only included the history of previous scars as more cesarean sections was significantly related to the occurrence of adherent placenta (P = 0.029).Presence of previous scar confers a high sensitivity (86.7%) and a high negative predictive value (94.3%).Doppler ultrasound predicted adherent placenta with different signs, the most sensitive being retroplacental hypervascularity and placenta covering the os (86.7%) while serosal disruption was the most specific sign (100.0%).The highest overall test performance signs were serosal disruption (89.0%), followed by presence of lacunae and absence of retroplacental clear zone (both 85.7%).Conclusion: Placenta previa confers high risk for adherent placenta, with 16.5% of cases of placenta previa having adherent placenta.Doppler ultrasound predicted adherent placenta with different signs, the most sensitive being retroplacental hypervascularity and placenta covering the os while serosal disruption was the most specific sign.Further well-designed research investigating abnormal decidualisation disorders and factors related to adherent placenta is required.