Objectives. To investigate the influence of 6 months of treatment with an oral contraceptive (OC) containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate on plasma viscosity (PV) in young women with polycystic ovary syndrome (PCOS).

Design. Patients with PCOS were assessed for PV before and after 6 months of treatment with an OC containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate. PV was determined by a viscometer Type 53610/I SCHOTT-Instruments, Mainz at 37°C.

Settings. Subjects were recruited from the Department of Obstetrics and Gynaecology, Division of Reproductive Endocrinology at the University Hospital of Patras, Greece.

Patients. The study included 66 young women with PCOS.

Main outcome measures. PV.

Results. In PCOS women as a whole, PV at baseline was 1.249 ± 0.049 mm²/s (n = 66). After 6 months of treatment with an OC containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate, PV was increased to 1.268  ±  0.065 mm²/s (p = 0.038). The difference between PV before and after 6 months of treatment with an OC containing 35 μg ethinyl estradiol and 2 mg cyproterone acetate (Δviscosity) was 0.01864  ±  0.071452 mm²/s. ΔViscosity was related to Δfibrinogen (r = 0.270, p = 0.046), to Δhematocrit (r = 0.514, p = 0.09) and to Δtriglycerides (r = 0.292, p = 0.021).

Conclusion. Young women with PCOS presented an increased PV under OC treatment with 35 μg ethinyl estradiol and 2 mg cyproterone acetate.