Objective To assess the prevalence of genitourinary Chlamydia trachomatis infection among women in different clinical settings, with a view to making decisions about who should be tested routinely.
Design Cross sectional study.
Setting One regional hospital and family planning clinic serving an urban centre.
Population Two thousand thirty-five sexually active women attending various outpatient settings.
Main outcome measures Prevalence of positivity by clinical setting, stratified by age.
Results Overall, prevalence of lower genital tract chlamydial infection was similar in a variety of clinical settings. Infertile women were the only exception, demonstrating a much lower prevalence. Stratifying the study population by age found a clear trend towards high prevalence in teenagers and virtually no infection in women over the age of 30 years.
Conclusions The prevalence of chlamydial infection in women is related to age, regardless of clinical presentation. In practice, opportunistic screening should target sexually active women under 30 years of age.