Efficacy of obstetric thromboprophylaxis and long-term risk of recurrence of venous thromboembolism

Abstract

The relative risk reduction in VTE during thromboprophylaxis was 88%. After pregnancy, the annual long-term risk of recurrence was 1%. The risk was most pronounced in the post-treatment period. There was an increased risk of bleeding complications among women given LMWH, but there was no effect on obstetric complications.

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

“…In the Swedish study above, LMWH was associated with an absolute increase in haematomas of 2.1% ( P  < 0.001) 4. A non‐randomised comparison of 1600 high‐risk women who did or did not receive LMWH after CD showed an increase in overall wound complications with LMWH (ARI = 3.8%; NNH = 26; P  = 0.002) and associated re‐hospitalisation (ARI = 1.3%; NNH = 77; P  = 0.017) 53.…”

“…Although LMWH might be expected to inhibit small clots destined to become symptomatic, there is no evidence that LMWH prevents clinical VTE when it is no longer given. Initial benefit may be offset by transient hypercoagulability following heparin treatment 4, 45. In two small RCTs comprising the Cochrane review, 2/109 women receiving LMWH developed VTE compared with 0/108 women receiving placebo 46, 47.…”

“…Case series of postpartum women who received LMWH are of limited help because they often lack a comparison group who did not receive LMWH. An exception is a Swedish study that compared women with a personal history of previous VTE who received antepartum and postpartum LMWH prophylaxis with control women who did not 4. A significant absolute risk increase (ARI) in haemorrhage >1000 ml was found (ARI = 4.4%; P  < 0.001), which would likely be lower for women only receiving LMWH postpartum.…”

“…Large studies of obstetric and non‐obstetric patients receiving prophylactic LMWH have demonstrated minimal risk 4, 17, 50, 52…”

“…Although evidence is limited, a small subset of pregnant and postpartum women is at very high risk of VTE. Women with a personal history of VTE, potent thrombophilia, or prolonged immobilisation usually receive and very probably benefit from antenatal and postpartum LMWH prophylaxis 4, 5. This perception of benefit has spread to women with more common risk factors, in whom the risk of VTE is lower.…”