An infection of the endometrium (membranous lining) of the UTERUS, FALLOPIAN TUBES and adjacent structures caused by the ascent of micro-organisms from the vulva and vagina. Around 100,000 women develop PID each year in the UK; most of those affected are under 25 years of age. Infection is commonly associated with sexual intercourse; Chlamydia trachomatis (see CHLAMYDIA) and Neisseria gonorrhoeae (see NEISSERIACEAE) are the most common pathogens. Although these bacteria initiate PID, opportunistic bacteria such as STREPTOCOCCUS and Bacteroides often replace them.

The infection may be silent – with no obvious symptoms – or symptoms may be troublesome, for example, vaginal discharge and sometimes a palpable mass in the lower abdomen. If a LAPAROSCOPY is done overt evidence of PID is found in around 65 per cent of suspected cases.

PID may be confused with APPENDICITIS, ECTOPIC PREGNANCY, ovarian cyst (see OVARIES, DISEASES OF) and inflammatory disorders of the intestines. Treatment is with a combination of ANTIBIOTICS that are active against the likely pathogens, accompanied by ANALGESICS. Patients may become seriously ill and require hospital care, where surgery is sometimes required if conservative management is unsuccessful. All women who have PID should be screened for sexually transmitted disease and, if this is present, should be referred with their partner(s) to a genito-urinary medicine clinic. Up to 20 per cent of women who have PID become infertile, and there is a seven- to ten-fold greater risk of an ectopic pregnancy occurring.