Anti-Xa Monitoring of Low-Molecular-Weight Heparin during Pregnancy: A Systematic Review

Abstract

Low-molecular-weight heparin (LMWH) is commonly used for preventing or treating venous thromboembolic disease (VTE) during pregnancy. The physiological changes in maternal metabolism have led to discussions on optimal LMWH dosing strategy and possible need for monitoring. The aim of this systematic review is to summarize and discuss whether LMWH dose adjustment according to anti-Xa provides superior effectiveness and safety compared with weight adjusted or fixed dosed LMWH in pregnant women. A systematic literature search was performed in PubMed, Embase, and Scopus on September 26, 2020. The study is reported according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Effectiveness was defined as episodes of thrombosis and safety as bleeding episodes. In total, 33 studies were included: 4 randomized controlled studies and 29 cohort studies. Prophylactic dosing strategies employing weight dosed, fixed dosed, or anti-Xa adjusted LMWH dosing performed equal in effectiveness and safety. In pregnant women with VTE or high thromboembolic risk, therapeutic weight–adjusted LMWH and weight plus anti-Xa-adjusted LMWH provided equal results in terms of effectiveness and safety. Pregnant women with mechanical heart valves (MHVs) received therapeutic anti-Xa-adjusted LMWH with four out of seven studies presenting mean peak anti-Xa within target ranges. Still, pregnant women with MHV experienced both thrombosis and bleeding with anti-Xa in target. Based on the results of this systematic review, current evidence does not support the need for anti-Xa monitoring when using LMWH as thromboprophylaxis or treatment during pregnancy. Nonetheless, the need for anti-Xa monitoring in pregnant women with MHV may need further scrutiny.

Application of low molecular weight heparins in umbilical artery thrombosis: A case series and review of the literature

“…[20] Long-term use of LMWHs during pregnancy proved to be well tolerated, although the incidence of adverse effects was low. [21–23] Santoro data appear to support the role of LMWHs in preventing further miscarriage in women with thrombotic disease and adverse history, and suggest that low molecular weight heparin may have therapeutic benefits that may temporarily improve maternal placental circulation parameters. [24]…”

“…[20] Long-term use of LMWHs during pregnancy proved to be well tolerated, although the incidence of adverse effects was low. [21][22][23] Santoro data appear to support the role of LMWHs in preventing further miscarriage in women with thrombotic disease and adverse history, and suggest that low molecular weight heparin may have therapeutic benefits that may temporarily improve maternal placental circulation parameters. [24] UAT is a rare occurrence with an incidence estimated to be 1 case in every 16,600 gestations (0.006%) [25] and up to 1 in every 250 deliveries (0.4%) [26] when only high-risk pregnancies are taken into consideration.…”

Effect of hydrocolloid dressing combined with low molecular weight heparin and calcium on scar hyperplasia in burn patients with venous thromboembolism

“…Long-term compression will reduce the blood supply of scar tissue, leading to tissue ischemia and limiting scar hyperplasia. 14 Stress will affect collagen formation and soften scars. However, after conventional germ pressure dressing, sterile gauze is used to cover the outer layer and bandage it under pressure.…”

British Society for Haematology guideline for anticoagulant management of pregnant individuals with mechanical heart valves

“…Although there is no firm evidence that monitoring LMWH with anti-Xa levels in pregnancy improves maternal outcomes, 22 there is evidence that standard fixed doses of LMWH are associated with a higher risk of MVT in pregnancy. 23,24 Fatal thrombotic events in two pregnant individuals in the HiP-CAT study occurred with low peak anti-Xa levels.…”