Chlamydial infection is a common, sexually transmitted disease which women can have without knowing. Untreated, it can lead to an infection of the womb and fallopian tubes called pelvic inflammatory disease (PID), which can cause infertility. There has been only one trial of chlamydia screening and this was in American women in 1992 and used outdated tests. We now need to see if screening using modern tests and self-taken swabs works in a high risk, young, multiethnic female population in the United Kingdom (UK).

The study is a randomised trial. It will involve asking women students in college bars to complete confidential questionnaires on sexual health and to provide self-administered vaginal swabs. We have successfully done this in a small pilot study. Participants will be told that the tests are for research purposes only and that if they think they may have been at risk of a sexually transmitted infection they should get checked at a clinic. If the trial shows that chlamydia screening using these new methods prevents PID, extending this community-based intervention nationwide could improve women's reproductive health and wellbeing and might prevent some women from becoming infertile

Background: Pelvic inflammatory disease (PID) is common and can lead to infertility, ectopic pregnancy or chronic pelvic pain.

Objectives: To see if screening and treatment of chlamydial infection reduces the incidence of PID over 12 months, and to investigate the natural history of chlamydial infection and the role of bacterial vaginosis (BV) in the development of chlamydia associated PID.

Design: Randomised trial over one year

Setting: Common rooms, bars and lecture theatres at universities and colleges in London, UK.

Participants: 2500 sexually active female students aged <28 years will be asked to complete a questionnaire on sexual health and to provide a self-administered vaginal swab and smear with follow up after a year.

Intervention: Following randomisation, vaginal swabs from intervention women will be tested for chlamydia by PCR and those infected referred for treatment. Vaginal swabs from control women will be stored and analysed after a year. Vaginal smears will be Gram stained and analysed for BV.

Main outcome measure: Incidence of clinical PID over 12 months in intervention and control groups.

Possible cases of PID will be identified from questionnaires and record searches. Confirmation of the diagnosis will be done by detailed review of medical records by two independent researchers blind to whether the woman is in the intervention or control group.

Inclusion Criteria:

• Sexually active

Exclusion Criteria:

• Never been sexually active
• Tested for chlamydia in past 3 months and no new sexual partner since then
• Pregnant