Diagnosing and Managing Placenta Accreta Spectrum

Understanding the High-Risk Context

The American College of Obstetricians and Gynecologists notes that placenta previa overlying a cesarean scar is the single most important risk factor for placenta accreta spectrum, present in 49% of all accreta cases 2
A patient with two prior cesareans and current placenta previa has a 40% risk for developing accreta, according to the American Journal of Obstetrics and Gynecology 1
The risk of accreta escalates dramatically with multiple cesareans: 3% with previa alone, 11% with previa plus one cesarean, 40% with two cesareans, 61% with three, and 67% with five or more, as reported by the American Journal of Obstetrics and Gynecology 1

Gray-scale ultrasound is both sensitive and specific enough to diagnose placenta accreta spectrum and should be the first-line imaging modality, with key findings including loss of the normal hypoechoic retroplacental zone, thinning or disruption of the hyperechoic uterine serosa-bladder interface, presence of placental lacunae, abnormal placental vascularity, and bladder wall irregularity, according to the American Journal of Obstetrics and Gynecology 1, 3
The absence of ultrasound findings does not rule out placenta accreta, and clinical risk factors remain equally important as predictors, with interobserver variability being substantial, as noted by the American Journal of Obstetrics and Gynecology 4

The American College of Obstetricians and Gynecologists recommends that patients with placenta accreta spectrum deliver at a level III or IV maternal care facility with a multidisciplinary team experienced in managing the condition, including maternal-fetal medicine subspecialists, pelvic surgeons, urologists, interventional radiologists, obstetric anesthesiologists, and blood bank with massive transfusion protocols 1, 5, 2
Planned delivery should occur at 34 0/7 to 35 6/7 weeks gestation to balance neonatal outcomes against maternal hemorrhage risk, as approximately 50% of women with accreta who wait beyond 36 weeks require emergent delivery for hemorrhage, according to the American College of Obstetricians and Gynecologists 5, 2
The standard approach is cesarean hysterectomy with the placenta left in situ, as attempting to remove the placenta results in catastrophic hemorrhage and should be avoided, as reported by the American Journal of Obstetrics and Gynecology 6, 5, 2