PID refers to the acute clinical syndrome attributed to the ascending spread of infection in women from the vagina and endocervix to the endometrium (lining of the uterus), fallopian tubes, and/or adjoining structures.
The ascent of infection has three stages:
– Infection of the cervix (cervicitis), which can lead to- Infection of the endometrium (endometritis) and eventually
– Infection of the endometrium (endometritis) and eventually
– Infection of the fallopian tubes (salpingitis).
Symptoms are not always obvious, and because PID is common among sexually active women, it is often known as the “silent epidemic”.
As already mentioned, PID can be caused by Chlamydia trachomatis and Neisseria gonorrhoeae, and also by other infectious agents.
Chlamydia is responsible for about 50% of PID cases, and gonorrhoea is the cause in 25% of cases. In young women with lower genital tract chlamydial infection the risk of developing salpingitis is one in 12, and one in 10 for women with gonorrhoea.
Non-gonococcal urethritis is the most common STD among Australian men. Chlamydia has been found to be the infectious agent in up to 70% of men with non-gonococcal urethritis, and in up to 80% of men with a related syndrome, post-gonococcal urethritis.
Each year in Australia an estimated 10,000 women are treated for PID as in-patients in hospitals, but as many as 10 to 30 times that number may be treated as outpatients or suffer more subtle forms of infection. It has also been estimated that chlamydia, the major cause of PID, costs between $75 million and $150 million a year in Australia.
There have been no Australian studies to estimate actual prevalence, however it is known that in the USA PID affects an estimated 4 million women each year, with a yearly cost of $3 billion. One in five women is hospitalised, and surgery is needed in one in 10 cases. There are 26,000 ectopic pregnancies each year in the USA as a result of salpingitis, and 200,000 women are left infertile.
Symptoms can include:
- lower abdominal pain or tenderness
- menstrual disturbances
- dysuria (burning on urination)
- a change in smell, colour, or amount of vaginal discharge
- deep pain during sexual intercourse
PID is usually caused by a sexually transmitted infection, but gynaecological surgical procedures such as abortion or the insertion of an intra-uterine device (IUD) can cause the infectious agents to spread upwards from the cervix and vagina. In Sweden it was found that 12% to 14% of all PID cases had been caused by gynaecological procedures within 6 weeks of admission.
IUDs may increase the risk of PID because the string attached to the device which extends down into the vagina acts as a wick for infection, allowing bacteria to ascend more easily into the upper genital tract. The relative risk of PID for sexually active young women using IUDs is 1.5 (i.e. a risk of PID one-and-a-half times greater than for young women not using IUDs). Those using barrier methods (i.e. condoms and diaphragms) have a relative risk of PID of 0.6 (i.e. the chance that they will acquire PID is about half that of those who do not use barrier methods).
The use of oral contraception appears to have a protective effect among sexually active young women with a relative risk of 0.3 (one-third the risk of those who do not use oral contraception). It is believed that the influence of progestogen on cervical secretions may prevent the ascent of microbes, as it does for sperm. However, these data were collected in the 1970s when higher dose pills were in use, and the protective effect of the currently more commonly used low-dose pills is not known.
PID can have devastating consequences. Salpingitis is the most frequent long-term complication because it can cause scarring of the tubes and infertility, making it impossible for the fertilised ovum to pass through the tube to the uterus.
One episode of PID doubles the risk of tubal infertility, and even a single attack can bring a seven fold increase in the chances of ectopic pregnancy. It has been estimated that one attack of PID carries a 20% risk of tubal blockage, rising to 30% after a second episode and as high as 75% after three or more episodes.
On the basis of these results it has been estimated that, of the theoretical group of women born in 1955, 15,000 per 100,000 would have had PID, and 2,000 per 100,000 would be infertile by their 30th birthday.
If untreated, PID can lead to chronic pain and sometimes severe disability.
Testing for the major causative organisms must be undertaken. However, sometimes laparoscopy (investigation by minor surgery) will be required to correctly diagnose PID.
Outpatient care may be sufficient for women with mild symptoms, but hospitalisation is necessary for women with more severe infection. Because PID can be caused by a variety of agents, drug treatments should be used that are active against a broad range of pathogens. Amoxycillin (penicillin) and doxycycline are usually prescribed.
It is imperative that regular male partners are tested for STDs and treated if necessary. In men, symptoms can be mild or non-existent so they may not present for testing or treatment.
- The use of condoms during penetrative sexual (vaginal or anal) intercourse.
- The use of condoms if an IUD is in place.
- Sexual practices other than intercourse carry less risk of transmitting the infections that cause PID.
- Where infection has occurred, it is important to avoid sexual contact involving the genitals during the course of treatment until a negative test result is obtained. This will aid healing and prevent transmission.