A placenta accreta spectrum is a group of placental abnormalities based on adherence to the placenta, including placenta accreta, increta, and percreta (UpToDate, 2019). Placenta accreta is an abnormal trophoblast invasion of part or all of the placenta into the myometrium of the uterine wall (Obstetric Care Consensus, 2018). Placenta accreta is when the placental villi attach to the myometrium. In placenta increta, the villi penetrate the myometrium; in placenta percreta, the villi penetrate through the myometrium to the uterine serosa or other organs (UpToDate, 2020). The chief risk factors for the placenta accreta spectrum are previous c-sections, previous placenta previa, or previous uterine surgery (Obstetric Care Consensus, 2018).
The placenta accreta spectrum is often diagnosed with ultrasound. An MRI may be used to evaluate the placenta further, but MRI has not been proven to improve the accuracy of diagnosis.
Women with the placenta accreta spectrum should deliver in an experienced, high-level maternity care center with a multi-disciplinary team (Silver & Barbour, 2015). This team should minimally include experienced obstetricians, maternal-fetal medicine specialists, pelvic surgeons, urologists, interventional radiologists, anesthesiologists, critical care experts, general surgeons, and neonatologists (Obstetric Care Consensus, 2018). These women should usually deliver between 34 0/7 – 35 6/7 weeks gestation. Earlier delivery may be recommended. Before the woman delivers, she should have pre-op consultations with appropriate providers and have her hemoglobin maximized. All team members should be aware of the time of the scheduled c-section. Cell saver should be used during surgery, and blood products should be available. Postoperative care may require intensive care (Obstetric Care Consensus, 2018).
Women with the placenta accreta spectrum are at high risk for hemorrhage. A hysterectomy may be necessary to stop hemorrhage during delivery. These women may also have an injury to other organs and require extensive surgery. The fetus is at risk for preterm delivery.