First principle: an ascending, often polymicrobial upper‑tract infection
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Classic organisms N. gonorrhoeae and C. trachomatis, but frequently polymicrobial (anaerobes, vaginal flora) — so only ~half of cases are GC/CT‑positive.
Recognition: a deliberately low threshold
The exclusions that must come first 🚩
- Pregnancy test — the deadly mimic is ectopic pregnancy.
- Consider appendicitis, ovarian torsion, ruptured/haemorrhagic cyst.
Management logic
- Broad empirical cover (GC + CT + anaerobes): a typical outpatient regimen is ceftriaxone (single IM) + doxycycline 14 days + metronidazole 14 days.
- Admit if: pregnancy, tubo‑ovarian abscess, severe illness, can't tolerate/oral‑fail, or surgical emergency not excluded.
- Review at 72 h; failure to improve → reassess/escalate.
Complications
- Tubo‑ovarian abscess (adnexal mass + systemic illness). 🚩
- Fitz‑Hugh–Curtis (perihepatitis → RUQ pain, "violin‑string" adhesions).
- Long term: tubal‑factor infertility and ectopic pregnancy — the reason urgency matters.
Pitfalls
- Excluding PID because GC/CT tests are negative.
- Forgetting the pregnancy test / ectopic.
Pearls
- 🎯 Any of CMT / uterine / adnexal tenderness → treat. Cover GC + CT + anaerobes.
- 🩺 The real cost of PID is future fertility — treat early, treat broadly, trace partners.
Next → An indolent infection that presents as infertility (Concept 28).