The risk of complications for PID increases with:
- time delay in receiving treatment
- number of episodes of PID
- severity of episodes of PID.
The most common and important complications are:
- tubal factor infertility (20%)
- ectopic pregnancy (10%)
- chronic pelvic pain (20%)
- up to 30% of patients requiring hospital admission will develop tubo-ovarian abscess.
For PID itself, the risk of ectopic pregnancy and infertility increases six times after one episode, and a further 17 times after two episodes.
In contrast, a single treated chlamydia infection alone does not increase the risk of ectopic pregnancy (relative risk: 1). However, the relative risk of an ectopic pregnancy increases to 11 after three episodes of chlamydia infection.