Pelvic inflammatory disease (PID) is a condition that involves infection and inflammation of the upper female genital tract, including the womb (uterus), fallopian tubes and ovaries. Any or all of these parts may be affected. PID is usually caused by an infection in the vagina and the neck of the womb (cervix) passing to the internal reproductive organs.
PID can be caused by many types of bacterial infection, but the majority of cases occur as a result of a sexually transmitted infection (STI), most commonly chlamydia trachomatis and neisseria gonorrhoea. When infection spreads from the cervix and along the fallopian tubes, it causes inflammation (salpingitis). This causes the lining of the tubes to become red and swollen, and makes the already narrow canals even narrower. Fertilised eggs may not be able to move along normally, increasing the risk of ectopic pregnancy (a pregnancy that occurs outside of the womb) and infertility (being unable to conceive naturally).
As the infection develops within the pelvis and becomes more widespread, PID may be diagnosed. If the infection remains untreated, the inflammation will eventually spread to the whole wall of the fallopian tubes, which can cause abscesses (pockets of infected fluid) to develop. The infection can then spread through the tubes and into the ovaries. The outer surfaces of the tubes may also start to stick to the surfaces of other organs such as the bladder and rectum.
If you have PID, further infection is common. After a first episode of PID, 20% of women have further episodes, mostly within two years.
About one in 50 women a year develops PID. It most commonly develops in sexually active women who are between 15 and 24 years of age. However, this figure may be an underestimate because many women with PID experience few or no symptoms.
