Placenta Accreta on the Rise, Research Suggests More Options for Safe Management


The increasing frequency of placenta accreta is raising new questions about the best way to manage this dangerous condition. At Brigham and Women’s Hospital researchers are creating a body of data to learn if some women with previa-accreta can be selected for a later delivery, if placenta accreta requires general anesthesia, and potential future risks for women who have had accreta during pregnancy.

Placenta accreta has grown from an estimated 1 in 4,000 deliveries in the 1970s to as many as 1 in 533 deliveries more recently. The increase is attributed to specific risk factors that are also on the rise:  Cesarean section, advanced maternal age, uterine surgeries, and in vitro fertilization (IVF).

Increased standardization of care for placenta accreta in recent decades has been a positive step for managing the condition, with physicians more uniformly following a standard protocol of delivery at 34 weeks, general anesthesia, and surgical intervention that includes hysterectomy.

“With our volume, we see a big range of cases and have found that some patients can deliver later – better for baby and for the mother,” said Daniela A. Carusi, MD, MSc, director of General Gynecology at Brigham and Women’s Hospital. In some cases, fertility can be preserved.

While most women with placenta accreta (especially those who are diagnosed antenatally) are referred to advanced centers, specialists continue to weigh the risks and benefits of various approaches for specific patient circumstances.

The number of cases at BWH – 30 to 50 per year – has enabled Dr. Carusi and colleagues to investigate ongoing areas of uncertainty. In research that looked retrospectively at births at BWH, they are creating a body of data to address these questions:

  • Can some patients with suspected previa-accreta be selected for a later delivery timing? Of 84 patients who reached 34-weeks gestational age with placenta previa and suspected accreta, those who had no risk factors for preterm birth were at low risk for an unscheduled delivery prior to 36 weeks, the authors found. Their study in Obstetrics and Gynecology Scandinavia in 2017 concluded that these patients, as well as those without concern for deep placental invasion or prior cesarean, may be good candidates for later delivery.
  • Do all women with suspected placenta accreta require general anesthesia (GA)? A study in Anesthesia & Analgesia earlier this year described 129 patients undergoing nonemergent cesarean deliveries for placenta previa with suspected placenta accreta, of whom 95 percent received neuraxial anesthesia (NA) as the primary anesthetic. Of the 72 patients among these who required hysterectomy, 15 (21 percent) required conversion to GA intraoperatively, with very low rates of complications or intensive care unit admission. The authors concluded that successful use of NA in most of the patients with suspected placenta accreta supported selective conversion to GA during hysterectomy with a focus on those with the greatest level of surgical complexity.
  • What are the risks in a future pregnancy for patients who have experienced a previous accreta? Dr. Carusi and colleagues have cared for increasing numbers of patients who preserve their fertility following a placenta accreta diagnosis. To counsel them for future pregnancies, they looked at the experience of 39 patients with pathologically-diagnosed placenta accreta who returned for a subsequent delivery. They concluded in Obstetrics and Gynecology that the risk for major hemorrhage or hysterectomy in the next pregnancy depends on the clinical context of the accreta delivery. They recommended preparation for major blood loss if the preceding pregnancy was complicated by hemorrhage or required treatment for retained placenta.

“We’re trying to help advanced centers see that you don’t have to treat all patients the same,” said Dr. Carusi said.

She urges obstetricians to be aware of a patient’s risk factors, to look for abnormal placenta on ultrasound, and to know when to refer a patient to a high-risk practice or a medical center with an experienced multidisciplinary team.

See the BWH guide to Caring for the Placenta Accreta Patient

To schedule a consultation with a Brigham and Women’s obstetrician specializing in placenta accreta, call the BWH Center for Fetal Medicine and Prenatal Genetics at (617)732-9894.


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