Routine tests of haemostasis and low-oestrogen oral contraceptives: what to expect?

Frequent requests from gynaecologists for testing of haemostatic parameters in women using hormonal contraception in order to predict development of thromboembolic disease, along with advancement of testing quality and accuracy, created the need to assess and compare the overall effect of oral contraceptives on today's routine haemostatic tests.

This 6-month prospective study included 195 women, first time users of oral contraceptives or with at least a 3-month pause before their entry in the study. Haemostatic changes were assessed by the following tests performed at three study time-points: at baseline, after three and after six months of taking oral contraceptives: prothrombin time, activated partial thromboplastin time, fibrinogen, resistance to activated protein C ratio, protein C activity, protein S activity, FVIII activity, antithrombin activity, plasminogen activity, alpha2-antiplasmin activity, inhibitor of plasminogen activator type 1 (PAI-1), and D-dimers. In addition, study subjects underwent genetic testing for FV Leiden mutation, FII G20210A mutation, and PAI-1 4G/5G polymorphism.

Significant changes were found in all haemostatic variables except for FVIII activity. With in-depth analysis, we showed that PAI-1 concentration decreased only in subjects with PAI-1 4G/5G genotype. None of the subjects developed venous thromboembolic disease during the study.

As most changes were within reference ranges, routine laboratory testing still does not appear to be recommendable in women without a known risk of thromboembolic disease.