Pelvic Inflammatory Disease (PID)
Definition and clinical importance
Pelvic inflammatory disease is an infection and inflammatory disorder of the upper female genital tract (endometrium, fallopian tubes, ovaries and adjacent pelvic structures). It is a common cause of acute lower abdominal pain in sexually active women and a preventable cause of infertility, ectopic pregnancy and chronic pelvic pain.
Early recognition and prompt empirical treatment in the emergency setting reduces immediate morbidity and long‑term sequelae.
Aetiology and epidemiology
PID is usually polymicrobial. Sexually transmitted organisms are important contributors but many cases are pathogen‑negative on testing and require empirical broad‑spectrum treatment.
- Common pathogens include Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium and mixed aerobic/anaerobic genital flora.
- Chlamydia trachomatis accounts for a substantial proportion of cases.
- Neisseria gonorrhoeae prevalence varies by setting and is important for public‑health management.
- Peak incidence is in younger sexually active women (≈20-24 years); presentations in older women (35-44 years) are more common in hospitalised cohorts and are less often STI‑related.
- Local incidence and resistance patterns should guide practice (consult UKHSA, BASHH and local Trust guidance).
Pathophysiology
PID results from ascending infection from the cervix to the uterus and fallopian tubes. Tubal inflammation causes scarring and adhesions, increasing the risk of infertility and ectopic pregnancy. Spread to peritoneal surfaces can produce tubo‑ovarian abscess (TOA), peritonitis or peri‑hepatic inflammation (Fitz‑Hugh‑Curtis syndrome).