Morbidly Adherent Placenta: Ultrasound Assessment and Supplemental Role of Magnetic Resonance Imaging

Morbidly adherent placenta or placenta accreta is being increasingly encountered in obstetrical practice mainly owing to the increasing rates of cesarean delivery. This condition is associated with increased maternal morbidity and mortality resulting from postpartum hemorrhage. When unsuspected, outcomes can be catastrophic to the pregnant woman. Timely diagnosis during the antenatal period, on the contrary, allows for optimal planning of a multidisciplinary management approach and delivery at a tertiary care institution. A higher index of suspicion in those at greatest risk such as in women with placenta previa and with history of some prior cesarean deliveries should lead to diligent antenatal evaluation for possible placenta accreta. Management of invasive placenta implantation often involves cesarean delivery hysterectomies; uterus-sparing alternatives to manage this condition can be an option in selected cases. Ultrasound imaging remains the modality of choice for the diagnosis. This review article discusses the ultrasound image findings in placenta accreta, its limitations and pitfalls, and the supplemental role of magnetic resonance imaging in the imaging evaluation of placenta accreta.