Placenta Accreta Spectrum (PAS)

What is Placenta Accreta Spectrum?

The placenta is an organ that develops in the uterus during pregnancy to allow exchanges of nutrients and oxygen between the fetus and the mother. In a normal pregnancy, the placenta is attached to the inner wall of the uterus without growing into it, and is expected to be delivered a few minutes after the delivery of the baby, whether during a vaginal or cesarean delivery.

In some patients, the placenta grows inside the wall of the uterus, and occasionally continues to grow outside of the uterus and invade into surrounding organs. This condition is called Placenta Accreta Spectrum (PAS), as it involves a range of severity (placenta accreta, increta or percreta) that correlates with the depth of invasion of the uterine wall.

As a result of this abnormal growth, the placenta does not separate spontaneously from the uterus after delivery. Attempts at manual separation of the placenta can be associated with life threatening hemorrhage. Involvement of surrounding organs adds to the complexity of this condition and its associated risks.

Although this is a relatively rare condition, its incidence is on the rise. Some of the common risk factors for this condition include a history of prior cesarean delivery, prior uterine surgery, and the location of the placenta covering the cervix (called placenta previa).

How is the diagnosis of Placenta Accreta Spectrum made?

The diagnosis of PAS is usually suspected during a routine prenatal ultrasound. Once a patient is referred to CUMC/NYP, a detailed ultrasound examination by a Maternal-Fetal Medicine specialist can confirm this suspicion and assess the severity of the condition. A pelvic MRI is frequently obtained to further delineate the extent of the placental abnormality and to assist in surgical planning. It is read by a dedicated radiologist with experience in the interpretation of MRIs in patients with PAS.  

How is Placenta Accreta Spectrum managed at CUMC/NYP?

The management of PAS is complex. At CUMC/NYP, it involves a multidisciplinary approach by a team of experts familiar with this condition. These include Maternal-Fetal Medicine specialists, Gynecologic Oncologists, Anesthesiologists, Neonatologists, Urologists, Interventional Radiologists, Vascular Surgeons and Intensivists. The blood bank plays a critical role and has the capacity to provide blood products to replace a massive hemorrhage at all times.

Once a patient is diagnosed with PAS, her prenatal care is taken over by the Maternal-Fetal Medicine team at the Mothers’ Center. In addition, the patient will have individual consultations with the different members of the multidisciplinary team involved in her care. When indicated, the patient may be recommended to be admitted to the antepartum unit for in-hospital observation until the day of her delivery. Psychological support and assistance with social services are provided as needed.

Management of individual patients is decided during regularly scheduled multidisciplinary meetings where the images are reviewed and an individualized approach to management is decided for each patient.

In general, delivery of patients with PAS is planned around 34-35 weeks of gestation. A hysterectomy will be required in most cases, but the ovaries are almost always preserved. In case an emergency delivery is indicated prior to the planned delivery date, the expert team at CUMC/NYP is available 24/7.

The team at CUMC/NYP is one of the most experienced in the country in the management of patients with PAS and is actively involved in research to find ways to constantly improve the outcomes of patients facing this condition.