MINNEAPOLIS – Women diagnosed with placenta accreta may face a significantly higher risk of developing venous thromboembolism (VTE) compared to other pregnant individuals, according to research presented at the American College of Obstetricians and Gynecologists (ACOG) 2025 Annual Meeting.

The study, conducted at a single center, revealed that despite the implementation of a specific VTE prevention protocol, known as a VTE bundle, only about 20% of placenta accreta patients received the complete intervention. rinat Tal, of the University of Michigan Medical School, Ann Arbor, Michigan, and colleagues presented these findings.

The researchers emphasized that “patients with placenta accreta spectrum are at risk for massive hemorrhage, need for blood transfusion, massive transfusion, long operating times, general anesthesia, and ICU stay, all of which increased patients’ risk for VTE beyond the preexisting elevated risk in pregnancy.”

Currently, there are no established guidelines for optimal VTE prophylaxis in patients with placenta accreta. Consequently, the research team evaluated the effectiveness of their institution’s VTE bundle in mitigating VTE risk within this patient population.

The Michigan Medicine VTE Bundle comprises four key elements: intraoperative management of subcutaneous heparin, resumption of anticoagulation within 8 hours postoperatively, continuation of anticoagulation throughout the hospital stay, and prescription of prophylactic anticoagulation upon discharge.

Researchers analyzed retrospective data from scheduled cesarean hysterectomies performed for suspected placenta accreta, excluding patients with cancer or incomplete 6-week postpartum data. Of the 90 patients meeting the criteria, only 22.2% received the complete VTE bundle.

The incidence of VTE in the cohort was 2.2%, with one patient in each group (complete bundle vs. incomplete bundle) experiencing VTE (P = .34). While the difference was not statistically significant, the researchers noted that the VTE incidence was approximately 18 times higher in this cohort compared to the general pregnant population.

among the 77.8% of patients who did not receive the full VTE bundle, 28.5% experienced a delay in the restart of postoperative anticoagulation but received the other three components. The remaining 71.4% were missing between one and three components, with 5.7% receiving no prophylactic anticoagulation at all.

The median age (34 years) and gestational age at delivery (34 weeks) were similar between the groups. However,the median body mass index was higher in the complete bundle group (34.7 vs. 31.8). A higher percentage of women in the incomplete bundle group had a previous C-section (92.9% vs.80%).

Patients in the incomplete bundle group experienced greater median blood loss (2500 mL vs. 1600 mL) and a higher rate of packed red blood cell transfusions (21.4% vs. 5%).

The researchers advocated for further investigation into the barriers preventing the consistent submission of the VTE bundle and emphasized the need for targeted quality improvement initiatives to enhance compliance.

expert Commentary

Alison G. Cahill, MD, associate dean of translational research and professor of women’s health at The University of Texas at Austin Dell Medical School, advised caution in interpreting the findings due to the study’s small size and preliminary nature. though, she acknowledged the importance of the research question.

“We’re constantly searching for opportunities to further reduce the chance of VTE in the setting of pregnancy for all kinds of all pregnant people.”

“We’re constantly searching for opportunities to further reduce the chance of VTE in the setting of pregnancy for all kinds of all pregnant people,” said CAHILL. She suggested that this study “raises the question as to whether or not this group [those with placenta accreta] should be considered separately” in seeking more ways to prevent VTE.

CAHILL added, “Just the idea of thinking about VTE risk – that there are differences, and what they look like, and how we might approach them differently – is an important investigative lane, especially because a lot of the data that we have for VTE primary prevention is from outside of the obstetric literature.”

No external funding or disclosures from the authors were reported. CAHILL had no disclosures.