Pelvic inflammatory disease (PID) Dr Trisha Macnair When the organs and tissues of the upper reproductive system (uterus, fallopian tubes and ovaries) become inflamed it can lead to long-term complications, including infertility.

In this article

What causes it? Who's affected?

What are the symptoms? How is it diagnosed?

What's the treatment? Fertility after PID

Infection is the main cause of PID. In at least 60 per cent of cases the infection is picked up during sex, and in almost half of these chlamydia is to blame.

Gonorrhoea causes about one in eight cases, and a variety of other bacteria may also cause PID.

The infection can originate elsewhere in the woman's body, for example in the bowel or bloodstream. Sometimes there's no evidence of infection and it isn't possible to find a cause.

Some factors increase the risk of PID, including the use of an intrauterine contraceptive device (IUD). Normally, the cervix produces mucus that blocks the passage of bacteria from the vagina into the upper part of the reproductive system, but bacteria can pass up the thread of an IUD into the uterus.

Some estimates suggest around one in 50 women has PID, but the symptoms are often so mild women are unaware they've had an episode of PID until they struggle to conceive.

This means the real incidence may be much higher - it probably affects more than one in ten women of reproductive age.

Women can develop PID at any age, but those who first have intercourse at a very young age are at higher risk.

Inflammation of the uterus, fallopian tubes and ovaries results in symptoms such as:

• Abdominal pain (one-sided or bilateral)
• Pain during sex
• Vaginal discharge
• Low back pain
• Irregular vaginal bleeding
• Fever, nausea and vomiting (in severe cases)

There may be no symptoms at all, especially when PID is caused by chlamydia. Eighty per cent of women who are infected with chlamydia are unaware they're infected.

In serious or untreated infections, the tissues may become extensively inflamed, with the production of pus that causes the uterus and fallopian tubes to stick to other organs such as the bladder and rectum.

Abscesses may form and peritonitis can develop.

Up to 20 per cent of women develop chronic pelvic pain after just one episode of PID. In severe disease, as many as 75 per cent of women experience chronic pain.

One in five women with PID will have recurrent episodes, usually within two years of the initial problem.

The symptoms are a guide to diagnosis. Blood tests may confirm inflammation, while swabs of the cervix or upper vagina can check for the bacteria known to cause PID.

Urine test are important, because infections of the urinary tract can cause similar symptoms. If the woman is sexually active, a pregnancy test will usually be done to rule out ectopic pregnancy. (PID is the most common wrong diagnosis when an ectopic pregnancy is missed.)

An ultrasound scan of the pelvis - and sometimes a laparoscopy or examination of the internal organs under anaesthetic using a telescopic device - may also be done to check for other possible causes of pelvic pain.

All women with PID need immediate treatment with antibiotics, often a combination of two or more drugs.

The woman's partner should also be screened for infection. If they're infected, they should be treated to avoid reinfection.

In the long term, scarring can cause blockages of the fallopian tubes and damage to the uterus. This can interfere with fertilisation and the implantation of an embryo, resulting in infertility.

Every episode of PID doubles the risk of infertility. Women with a history of PID have up to ten times the average risk of an ectopic or tubal pregnancy.

The more severe the episode of PID, and the longer treatment is delayed, the greater the risk of damage to the fallopian tubes. If you have symptoms of PID, get checked by your GP as soon as possible.

Modern fertility treatments can help women having problems conceiving as a result of PID.