placenta accreta

Placenta accreta represents a spectrum of abnormal placental adherence caused by partial or complete absence of the decidua basalis and imperfect development of the fibrinoid layer (Nitabuch layer). This allows chorionic villi to directly contact and invade the myometrium. The condition exists on a spectrum: accreta (villi adhere to myometrium), increta (villi invade into myometrium), and percreta (villi penetrate through myometrium, potentially into adjacent organs like bladder). Risk factors include prior uterine surgery (especially cesarean section), placenta previa, advanced maternal age, multiparity, and prior placenta accreta. The primary clinical significance is severe postpartum hemorrhage due to inability of the placenta to separate spontaneously, often requiring hysterectomy for maternal survival. Diagnosis is made via ultrasound showing loss of retroplacental clear zone, irregular intraplacental lacunae, and increased vascularity on Doppler. MRI can provide additional detail for surgical planning. Management involves multidisciplinary team approach with planned cesarean hysterectomy at 34-36 weeks to minimize bleeding complications.