Revised obstetric VTE prophylaxis protocol prevents wound hematomas

Adopting a more conservative approach to venous thromboembolism (VTE) prophylaxis results in reduced rates of wound hematomas, with no increase in postpartum VTE, according to a recent study presented at SMFM 2024.

“In 2016 our institution adopted VTE prophylaxis guidelines based on American College of Obstetricians and Gynecologists (ACOG) recommendations,” said the investigators led by Macie L Champion from the University of Alabama at Birmingham, Alabama, US.

The ACOG guidelines recommend heparin-based chemoprophylaxis for those with at least two VTE risk factors such as obesity, chorioamnionitis, and pre-eclampsia.

“As institutional data showed increased wound hematomas and no difference in VTEs, we adopted a more restricted approach requiring three or more risk factors with fewer conditions considered risk factors (severe pre-eclampsia vs all pre-eclampsia),” the investigators said.

In this retrospective cohort study, Champion and her team evaluated the outcomes after the implementation of this revised obstetric thromboprophylaxis protocol among women who delivered at their institution between 1 January 2016 and 31 December 2018 (original guidelines) and between 1 December 2021 and 31 May 2023 (revised guidelines).

High-risk patients (ie, those with thrombophilia, prior/current VTE) on antepartum anticoagulation were excluded from the analysis.

Clinical diagnosis of wound hematoma up to 6 weeks postpartum was the primary outcome, while new diagnosis of postpartum VTE was secondary. Champion and colleagues compared baseline characteristics and outcomes between groups and estimated adjusted odds ratios (aOR) with 95 percent confidence intervals (CIs) of said outcomes using the original guideline group as the reference.

More restrictive

A total of 17,489 patients were included in the analysis. Of these, 12,430 (71 percent) were in the original guidelines groups and 5,029 (29 percent) in the revised group. [SMFM 2024, abstract 3]

Chemoprophylaxis rates decreased by 50 percent, from 16 percent during the original guidelines to only 8 percent following the revision. Baseline characteristics such as age, race, comorbidities, and insurance status differed between groups.

The more restrictive guidelines correlated with a more than 50-percent reduction in any wound hematoma compared with the original guidelines (0.7 percent vs 0.3 percent; aOR, 0.38, 95 percent CI, 0.21‒0.67). This association was primarily driven by a 50-percent decrease in superficial wound hematomas (0.6 percent vs 0.3 percent; aOR, 0.43, 95 percent CI, 0.24‒0.75).

Of note, no increase was observed in VTE, deep vein thrombosis, or pulmonary thromboembolism, according to the investigators.

In a previous study, a group of researchers reported the association of a risk-based anticoagulation protocol for obstetric VTE prophylaxis with increased wound hematomas, unplanned procedures, and blood transfusions without decreased VTEs. [Am J Obstet Gynecol 2021;224:S41-S42]

“Given that, for every 60,000 obstetric patients under this protocol needed to prevent 1 VTE, there were an associated 180 wound hematomas, routine risk-based anticoagulation for VTE prophylaxis in obstetric patients should be strongly reconsidered,” the researchers said.