Placenta Accreta Spectrum: From Abnormal Adherence to Invasive Disorders

Abstract

Placenta accreta spectrum (PAS) occurs when all or part of placenta is abnormally attached to the myometrium due to partial or total absence of decidua basalis and improper development of fibrinoid and nitabuch's layer. It encompasses a range of abnormal placental adherence disorders, including placenta accreta, increta, and percreta, characterized by progressive invasion of chorionic villi into the myometrium and beyond. It is associated with prior cesarean delivery, placenta previa, uterine surgery, and assisted reproductive techniques. PAS has emerged as a major contributor to severe maternal morbidity and mortality, owing to its association with life-threatening hemorrhage, massive transfusion, disseminated intravascular coagulation, and multiorgan dysfunction. Prenatal diagnosis through high-resolution ultrasound and magnetic resonance imaging is crucial for optimal management, enabling multidisciplinary planning and delivery at specialized centers. Management strategies vary depending on disease extent, maternal condition, and reproductive wishes, ranging from cesarean hysterectomy to conservative approaches that preserve fertility. Despite advances in imaging and surgical techniques, PAS remains a critical challenge in modern obstetrics, underscoring the need for early risk identification, preventive strategies, and standardized management protocols to improve maternal outcomes.