Study Finds Higher Risk of Maternal Complications in Cesarean Deliveries with Low-Lying Placenta: ACOG annual meeting

According to the new data, patients with a low-lying placenta who underwent cesarean deliveries faced a higher risk for multiple complications even if they did not have placenta previa. The findings were presented at the annual meeting of the American College of Obstetricians and Gynecologists.

"Rates of postpartum hemorrhage, preterm delivery, placenta accreta, and need for transfusion and hysterectomy were all significantly higher in patients with low-lying placenta than in patients without," reported Jacob Thomas, MD, of Advocate Aurora Health in Chicago, Illinois, and Ascension Illinois St. Alexius Medical Center in Hoffman Estates, at the meeting.

A low-lying placenta is defined as a placental edge less than 20 mm from the internal os but not covering it. However, most studies looking at low-lying placentas group them with placenta previa, making it difficult to know if there are differences in risk of adverse outcomes for those who don’t have placenta previa.

The researchers conducted a retrospective analysis of all patients who underwent a cesarean delivery in the National Inpatient Sample from 2017 to 2019 through the Healthcare Cost and Utilization Project from the Agency for Healthcare Research and Quality.

The researchers compared outcomes among patients with ICD-10 codes for low-lying placenta to patients without low-lying placenta, after excluding placenta previa patients. The researchers specifically looked at preterm delivery, hysterectomy, hemorrhage, placenta accreta spectrum (PAS), shock, sepsis, blood transfusion, and disseminated intravascular coagulation.

The study revealed the following findings:

· Among 700,635 patients with cesarean deliveries in the database, 0.4% had low-lying placenta. These patients were more likely to be anemic, older, and delivered at a large or urban teaching hospital. They were less likely to have public insurance or a previous cesarean.

· After controlling for confounders that differed between the two populations, the researchers found a higher likelihood of all adverse maternal outcomes studied in patients with low-lying placenta.

· These patients had three times greater risk for preterm delivery (adjusted odds ratio [aOR], 3.07) and nearly three times greater risk for shock (aOR 2.55), and transfusion (aOR, 2.56).

· Compared to those without a low-lying placenta, the risk for patients with low-lying placenta was even higher for hysterectomy (aOR, 9.42), hemorrhage (aOR, 8.87), and PAS (aOR, 13.41).

· Within the group with a low-lying placenta, older patients were modestly, but significantly, more likely to have hemorrhage, hysterectomy, and PAS (aOR, 1.06 for all).

· The risk was more elevated and significant in patients with tobacco use for hemorrhage (aOR, 1.43), PAS (aOR, 1.40), and hysterectomy (aOR, 1.40).

· Patients with anemia were also significantly more likely to experience PAS (aOR, 1.34).

“Interestingly, prior cesarean was not associated with increased hysterectomy or hemorrhage rates in this population,” the researchers reported. The findings can also “help guide research in terms of questions for the future,” Dr. Thomas said, such as looking at complication rates for vaginal deliveries in those with low-lying placenta.

As obstetricians continue to navigate the complexities of managing high-risk pregnancies, studies like this provide valuable insights into optimizing maternal outcomes and ensuring the safety of both mother and baby during cesarean deliveries for placenta previa. By identifying risk factors and implementing evidence-based interventions, healthcare providers can strive to minimize complications and improve the overall quality of care for women facing this challenging obstetric scenario.