Contraception, venous thrombosis and biological plausability.

Exogenous use of hormones leads to different impact on coagulation. Usually estrogen leads to an activation of coagulation, while use of progestogens alone do not. Combined oral contraceptives (COC) differs significantly regarding VTE risk depending on amount of estrogen and type of progestagen: COC containing desogestrol, gestoden or drospirenone in combination with ethinyl-estradiol (EE) (so called 3rd or 4th generation COC) are associated with a higher VTE risk than COC with EE and levonorgestrel or norethisterone (so called 2nd generation COC). The VTE risk for transdermal COC like vaginal ring (NuvaRing) or patch (Evra) is as high than than for COC of 3rd or 4th generation. 2nd generation COC should therefore be the first choice when prescribing hormonal contraception. Most PROGESTAGEN-only contraceptive methods do not increase VTE risk significantly. In patients with a history of venous thromboembolism (VTE) and /or a known thrombophilic defect COC are contraindicated, but progestagen-only contraceptives can be safely used in this patient group. New kinds of COC without EE but with Estradiolvalerat or Estradiol showed a much lower degree of coagulation activation than "classical" COC containing EE. If newer COC with Estradiolvalerat or Estradiol have a lower VTE risk, remains to be elucidated.