The CPLAN study: Clotting Parameters after medicaL AbortioN.

BACKGROUND

There is paucity of information on coagulation parameters throughout pregnancy, the puerperium, and post-abortion - and how these relate to venous thromboembolism (VTE) risk. Guidance for thromboprophylaxis post-abortion is guided by expert opinion and extrapolated from post-birth, with recommendations varying from 0 to 6 weeks duration.

METHODS

We conducted a study in a community abortion clinic in Edinburgh, UK March-August 2021. We recruited healthy pregnant women requesting medical abortion (<12 weeks gestation) and healthy, non-pregnant women (controls). Blood samples were taken prior to abortion and 10-14 days afterwards. Controls provided a single sample. We assessed laboratory markers of coagulation (Clauss-fibrinogen, prothrombin time, activated partial thromboplastin time, platelets) and viscoelastic measures using the ClotPro® system. We compared the control group with the pregnancy group pre- and post-abortion.

RESULTS

We recruited 45 women (24 pregnant, 21 non-pregnant). Clauss-fibrinogen was significantly elevated pre-abortion compared to controls (3.4 g/L vs 2.8 g/L, p = 0.04), although remained within normal range. Two viscoelastic measures showed pro-coagulant changes, one pre-abortion and one post-abortion compared to controls. The absolute differences were small and remained within normal ranges.

CONCLUSION

There were minimal differences in measures of coagulation in first trimester pregnancy, that largely resolved 10-14 days after medical abortion. Shorter courses of thromboprophylaxis might be sufficient compared to post-birth for those at high risk of VTE.