Objective: Oral contraceptive use has been associated with a lower risk of symptomatic pelvic inflammatory disease but a higher risk of chlamydial cervicitis. To explain these seemingly contradictory findings, we asked whether oral contraceptive use was more common among women with unrecognized endometritis than among women with recognized endometritis.
Study design: A multicenter case-control study was performed. Women without signs of pelvic inflammatory disease were ascertained through contact tracing of partners with sexually transmitted diseases or through presentation with cervicitis. Women with symptomatic pelvic inflammatory disease met a set of standard clinical criteria. We compared the 43 cases without signs of pelvic inflammatory disease but with endometritis ("unrecognized endometritis") with the 111 controls with recognized pelvic inflammatory disease and endometritis ("recognized endometritis").
Results: Women with unrecognized endometritis were 4.3 times (95% confidence interval 1.6 to 11.7) more likely than women with recognized endometritis to use oral contraceptives.
Conclusion: Future studies need to fully characterize the risks and benefits of oral contraceptives in relation to sexually transmitted diseases.