Pelvic inflammatory disease (PID) usually starts with a bacterial infection and inflammation of the cervix (cervicitis). This is usually caused by gonorrhea or chlamydia. PID is also linked to an imbalance of the organisms normally found in the vagina (bacterial vaginosis). The bacteria then spread to other female reproductive organs.

Sometimes PID starts after bacteria are carried beyond the cervix by an invasive procedure. This could be the insertion of an intrauterine device (IUD), a dilation and curettage (D&C), an induced abortion, or a hysterosalpingogram test (which uses a tube to inject dye through the cervix into the uterus and fallopian tubes for X-ray imaging).

In some cases, infection moves into a fallopian tube and ovary. This can form a pocket of pus called a tubo-ovarian abscess. After having this problem, as many as 93% of women cannot become pregnant.²

PID causes inflammation in the uterus and fallopian tubes. In turn, the inflammation can form scar tissue (adhesions) in the abdominal cavity and the reproductive organs. This does not always cause symptoms. The scar tissue can lead to:

• Infertility. Scarring inside the fallopian tubes is permanent and can twist or block the tubes with scar tissue or fluid, leading to tubal infertility. About 1 in 10 women cannot become pregnant after having PID once. After having PID three or more times, as many as 7 in 10 women become infertile.²
• Chronic pelvic pain, affecting nearly 20% of women who have had PID.³ Chronic (ongoing) pelvic pain is usually caused by internal scarring (adhesions) and is difficult to treat. For more information, see the topic Chronic Female Pelvic Pain.
• Tubal (ectopic) pregnancy. About 10% of pregnancies that follow PID are in a fallopian tube.³ Scar tissue can trap a fertilized egg in a fallopian tube, where it begins to grow. This can become a life-threatening problem. It must be treated right away with medication or surgery to end the pregnancy.

PID may also occur inside the abdomen as:

• A pocket of pus (abscess) in the pelvis.
• An infection and inflammation of the lower abdomen (pelvic peritonitis).
• Inflammation around the outside of the liver (perihepatitis).

The longer PID treatment is delayed, the more likely you are to have permanent damage. Similarly, each recurrent pelvic infection increases your risks of tubal infertility, chronic pelvic pain, and ectopic pregnancy.²