- In the UK, the lifetime prevalence of PID is 1.7%
- PID may be asymptomatic
- Risk factors are:
- the most important risk factor is a previous history of chlamydia, gonorrhoea infection or PID
- the 16–24-year-old age group: five-times higher risk compared with control group
- vaginal 'douching' (see below)
- smoking and low socioeconomic group
- recent intrauterine contraceptive device insertion: within 4 weeks of insertion in woman at a low risk of sexually transmitted infection
- recent intrauterine procedure e.g hysterosalpingogram, intrauterine contraceptive device, termination of pregnancy, surgical management of miscarriage, embryo transfer
- high frequency of partner change
- lack of barrier contraception
- sex during or just after menstruation
- genetic factors may also play a role
- Combined oral contraceptive pill and the use of barrier contraceptions are associated with reduced PID incidence, possibly because of altered presentation of the infection. Intrauterine devices cause very little increase risk of PID, which is limited to the first 4 weeks of insertion.
The practice of 'cleaning' the vagina by squirting water or vinegar (known as douching) more than three times in 1 month increases the risk of PID by 300% compared with not douching. It also increases the risk of endometritis and ectopic pregnancy.