Venous thromboembolism in women using hormonal contraceptives. Findings from the RIETE Registry.

There is scarce information on the clinical characteristics of contraceptive users who develop venous thromboembolism (VTE). RIETE is an ongoing registry of consecutive patients with symptomatic, objectively confirmed, acute VTE. We analyzed the clinical characteristics and additional risk factors for VTE in all enrolled women aged <50 years who were using or not using contraceptives at presentation with VTE. Of 1,667 women aged <50 years enrolled in RIETE as of December 2007, 593 (36%) were contraceptive users. Of 270 aged <25 years, 190 (70%) were users. Ninety-two contraceptive users (16%) had overweight, 89 (15%) were obese. Of 951 women with no additional risk factors for VTE (i.e. recent surgery, immobility or cancer) 457 (48%) were contraceptive users. Eighty-seven (15%) users had recent immobility for >/=4 days, 44 (7.4%) were postoperative. The most common reason for immobility was lower limb trauma not requiring surgery; 25% of users with recent immobility had received thromboprophylaxis. The most common type of surgery was non-major orthopaedic surgery. Twenty-one (48%) users with postoperative VTE had received prophylaxis. The percentage of users and non-users who tested positive for thrombophilia was similar. Contraceptive use remains the most frequent risk factor for VTE in women at fertile age. Identifying those at increased risk for VTE seems to be difficult. In the meanwhile, a higher use of thromboprophylaxis during immobility or minor surgery should be warranted.