Postpartum venous thromboembolism prophylaxis may cause more harm than benefit: a critical analysis of international guidelines through an evidence-based lens

Abstract

Based on prediction models and expert opinion, most obstetric venous thromboembolism guidelines recommend low-molecular-weight heparin for many postpartum women, including most delivering by caesarean. Scrutiny reveals major oversights: prediction models are based on studies that report asymptomatic deep vein thrombosis; risk estimates are not adjusted for time exposure; and harm caused by heparin has been overlooked. The benefits of heparin are exaggerated and its harms are under-appreciated. Estimates of the numbers-needed-to-treat and harm are universally lacking. This paper critically reviews the evidence and quantifies the benefit and harm from low-molecular-weight heparin in postpartum women with common risk factors.

Funding: This work was unsponsored and unfunded.

Tweetable abstract: Randomised trials should demonstrate more benefit than harm before widespread postpartum low-molecular-weight heparin is recommended.

Keywords: Caesarean section; evidence-based medicine; guidelines; postpartum; prophylaxis; venous thromboembolism.

Figure 1

Rate of VTE per 100 000 person‐years by antepartum and postpartum week. (From Sultan et al. Br J Haematol 2011, with permission.) Risk during the first postpartum week = 680/100,000. Total 12 postpartum weeks = 2870/100,000. Proportion of total postpartum risk during the first week = 680/2870 = 0.24.