What causes it?

As infection develops and spreads within the pelvis, PID may be diagnosed. If infection remains untreated, the inflammation eventually spreads to involve the whole wall of the fallopian tubes, with pus coming from the open ends at the ovaries. The outer surface of the tubes may begin to stick to other nearby organs such as the bladder and rectum.

Recurrent infection is common and after an initial episode of PID, 20% of women have further episodes, mostly within two years. It is estimated that 1.7% of women have PID, and this is almost certainly an underestimate, because many women are unaware of having contracted a sexually transmitted disease and are either free of symptoms, or unaware of the cause of their symptoms.

Although PID can often be treated quickly and effectively with antibiotics, if left untreated it can cause damage to fallopian tubes, thus increasing the risk of ectopic pregnancy and infertility.

Around 1 in 10 women with a mild case of PID are found to be infertile as a result of damage to their fallopian tubes. This can rise to 1 in 2 women, who have more severe or repeated infections.