Using anticoagulants to prevent obstetric VTE may increase risk of bleeding complications

UAB women’s health experts found that prophylactic anticoagulation guidelines did not reduce risk of venous thromboembolisms but did increase the risk for bleeding complications in the general obstetric population.

pitkin streamUAB women’s health experts found that prophylactic anticoagulation guidelines did not reduce risk of venous thromboembolisms but did increase the risk for bleeding complications in the general obstetric population.
Photography: Lexi Coon
Venous thromboembolism, or blood clots that start in a vein, account for 9.2 percent of maternal deaths following pregnancy in the United States. To reduce the risk of maternal VTE, national guidelines advise using a risk-based strategy to administer anticoagulation drugs during pregnancy or in the postpartum period in an effort to prevent VTE.

Researchers from the University of Alabama at Birmingham conducted one of the largest retrospective studies to evaluate the safety and efficacy of the guidelines. The findings, published in Obstetrics & Gynecology, or “The Green Journal,” showed no decrease in the rate of VTE but presented a significant increase in bleeding complications, such as significant wound bleeding complications, hematomas and an increased need for blood transfusions.

“Heparin-based anticoagulant drugs are widely used in the U.S. as a method of obstetric VTE prevention despite incomplete evidence of their safety and efficacy,” said Akila Subramaniam, M.D, maternal-fetal medicine associate professor in the UAB Marnix E. Heersink School of Medicine and senior author of the study. “Given our findings, we suggest that current recommendations for the general obstetric population be revisited and potentially reconsidered.”

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UAB implemented the strict treatment guidelines from the American College of Obstetrics and Gynecology in 2016. Guidelines included a 15-fold increase in heparin-based prophylaxis given to the general obstetric population.

The team then retrospectively evaluated more than 24,000 patients who delivered at UAB Hospital from January 2013 to December 2018. Deliveries were categorized as “pre-protocol” from January 2013 to December 2015 and “post-protocol” from January 2016 to December 2018. Patients with active-VTE or high-VTE-risk deliveries were excluded as this is a population well-known to benefit from anticoagulation given their exceptionally high risk.

Akila InsideAkila Subramaniam, M.D., associate professor in the UAB Division of Maternal-Fetal Medicine
Photography: Chris Carmichael
While results showed similar frequencies in postpartum VTEs in both time periods, postpartum wound bleeding complications doubled in the post-protocol group. Additionally, the need for unplanned surgical procedures significantly increased post-protocol.

“There is no question that heparin-based anticoagulation is justified in obstetric patients with active VTE or high-risk VTE,” Subramaniam said. “However, VTE is a rare event, and there is a lack of evidence of the treatment’s safety and efficacy to support its expanded use in the general obstetric population.” 

Subramaniam notes that, while they conducted a retrospective study and not a clinical trial, their findings led to a dramatic scale-back of prophylaxis provided to the UAB obstetric population.

“The benefit of UAB’s being a tertiary referral center is that we were able to capture a

demographically, socioeconomically and geographically diverse study population,” Subramaniam said. “However, more studies and trials need to be conducted to make further practice recommendations.”

The UAB Department of Obstetrics and Gynecology received a 2021 Roy M. Pitkin Award for their findings. The award is selected by the editors of The Green Journal and recognizes outstanding published articles.