Pelvic inflammatory disease (PID) is a bacterial infection of the female upper genital tract, including the womb, fallopian tubes and ovaries.

Most cases of PID are caused by an infection in the vagina or the neck of the womb (cervix) that has spread to the reproductive organs higher up.

Many different types of bacteria can cause PID, but most cases are the result of a chlamydia or gonorrhoea infection (see Causes for more information).

What happens?

When infection spreads upwards from the cervix (entrance to the womb), it causes one or more of the following:

• endometritis: inflammation and infection of the endometrium (womb lining)

• salpingitis: inflammation and infection of the fallopian tubes

• parametritis: inflammation and infection of the tissue around the womb

• oophoritis: inflammation and infection of the ovaries

• an abscess: a pocket of infected fluid in the ovary and fallopian tube

• pelvic peritonitis: inflammation and infection of the peritoneum (lining of the inside of the abdomen)

If you develop salpingitis, the lining of the fallopian tubes swells and the already narrow canals become even narrower. This means that fertilised eggs may not be able to move along them normally, increasing the risk of ectopic pregnancy (a pregnancy that occurs outside of the womb) and infertility. See Complications for more information.

Who is affected?

PID most commonly develops in sexually active women between the ages of 15 and 24. The disease is fairly common and is the reason for 1 in 60 visits to GPs by women under 45. Many more women with PID experience few or no symptoms.

Outlook

If diagnosed at an early stage, PID can be treated quickly and efficiently with antibiotics. However, if left untreated, it can lead to more serious long-term complications such as an ectopic pregnancy.

Further infection is common. After a first episode of PID, one in five women has more episodes, mostly within two years. Repeated episodes of PID are associated with an increased risk of infertility.