Pelvic Inflammatory Disease (PID) — Exam Notes

1. Definition

• Endometritis
• Salpingitis
• Tubo-ovarian abscess (TOA)
• Pelvic peritonitis

2. Etiology

• Classically sexually transmitted: N. gonorrhoeae and C. trachomatis — but their contribution is declining; only ~50% of acute PID cases test positive for either organism now.
• Polymicrobial — vaginal flora also implicated: anaerobes, G. vaginalis, H. influenzae, enteric gram-negative rods, Streptococcus agalactiae.
• Also implicated: CMV, T. vaginalis, M. hominis, U. urealyticum, and possibly M. genitalium (associated with milder symptoms).
• BV is frequently co-present with PID, though a causal role in incidence is unclear.
• Screening/treating chlamydia and gonorrhea in sexually active women reduces PID risk.

3. Diagnosis

Why it's difficult

• Wide variation in symptoms/signs; many women have subtle, nonspecific symptoms or are asymptomatic.
• Delay in diagnosis → inflammatory sequelae (infertility, ectopic pregnancy, chronic pelvic pain) — even mild/subclinical PID carries this risk.
• Laparoscopy gives more accurate diagnosis of salpingitis but is not always available/justified, and misses endometritis and subtle tubal inflammation.
• Clinical diagnosis has a positive predictive value of 65–90% for salpingitis (vs laparoscopy); higher PPV in young sexually active women, STD clinic attendees, high-prevalence communities.
• No single finding is both sensitive and specific → low threshold for clinical diagnosis is recommended.

Minimum criteria — start empiric treatment if:

• Cervical motion tenderness, OR
• Uterine tenderness, OR
• Adnexal tenderness

Additional criteria (increase specificity)

• Oral temperature >38.3°C (>101°F)
• Abnormal cervical mucopurulent discharge or cervical friability
• Abundant WBCs on saline microscopy (wet prep) of vaginal fluid
• Elevated ESR
• Elevated CRP
• Laboratory-confirmed cervical infection with N. gonorrhoeae or C. trachomatis

If cervical discharge is normal and no WBCs seen on wet prep → PID diagnosis unlikely; look for alternative cause. Wet prep can also detect concurrent BV/trichomoniasis.

Definitive/specific criteria (for select cases)

• Endometrial biopsy showing histopathologic endometritis
• Transvaginal USG/MRI: thickened, fluid-filled tubes ± free pelvic fluid or tubo-ovarian complex; Doppler showing tubal hyperemia
• Laparoscopic findings consistent with PID

Differential diagnosis to exclude

Investigations for all women diagnosed with PID

4. Management

General principles

• Treat empirically and immediately once presumptive diagnosis made — do not wait for culture confirmation (early treatment prevents long-term sequelae).
• Regimens must give broad-spectrum empiric coverage, always effective against N. gonorrhoeae and C. trachomatis, plus anaerobic coverage (anaerobes like Bacteroides fragilis cause tubal/epithelial destruction; BV often coexists).
• Mild-to-moderate PID: oral and parenteral regimens have similar efficacy — outpatient treatment is reasonable.

Criteria for Hospitalization

• Surgical emergency (e.g., appendicitis) cannot be excluded
• Tubo-ovarian abscess
• Pregnancy
• Severe illness, nausea/vomiting, or oral temp >38.5°C (101°F)
• Unable to tolerate/follow outpatient oral regimen
• No clinical response to oral antimicrobials

A. Recommended Parenteral Regimens

1. Ceftriaxone 1 g IV q24h + Doxycycline 100 mg PO/IV q12h + Metronidazole 500 mg PO/IV q12h
2. Cefotetan 2 g IV q12h + Doxycycline 100 mg PO/IV q12h
3. Cefoxitin 2 g IV q6h + Doxycycline 100 mg PO/IV q12h

• Doxycycline preferred orally (painful IV; similar bioavailability).
• Transition to oral therapy usually within 24–48 hrs of clinical improvement.
• If TOA present: continue >24 hrs of inpatient observation; complete 14 days total with doxycycline 100 mg BD + metronidazole 500 mg BD.

• Ampicillin-sulbactam 3 g IV q6h + Doxycycline 100 mg PO/IV q12h (good TOA coverage)
• Clindamycin 900 mg IV q8h + Gentamicin (loading 2 mg/kg, then 1.5 mg/kg q8h, or once-daily 3–5 mg/kg)
  • On clinical improvement (24–48h): switch to Clindamycin 450 mg PO QID or Doxycycline 100 mg PO BD to complete 14 days.
  • If TOA present: prefer Clindamycin 450 mg PO QID (better anaerobic cover) over doxycycline alone, plus doxycycline.

B. Recommended IM/Oral Regimens (mild-moderate PID)

1. Ceftriaxone 500 mg IM single dose (1 g if ≥150 kg) + Doxycycline 100 mg PO BD × 14 days + Metronidazole 500 mg PO BD × 14 days
2. Cefoxitin 2 g IM single dose + Probenecid 1 g PO (concurrently) + Doxycycline 100 mg PO BD × 14 days + Metronidazole 500 mg PO BD × 14 days
3. Other parenteral 3rd-gen cephalosporin (ceftizoxime/cefotaxime) + Doxycycline + Metronidazole (same doses)

• Levofloxacin 500 mg PO once daily ± Metronidazole 500 mg BD × 14 days, OR
• Moxifloxacin 400 mg PO once daily (preferred quinolone for M. genitalium coverage) ± Metronidazole, OR
• Azithromycin 500 mg IV daily ×1–2 doses → 250 mg PO daily + Metronidazole 500 mg BD × 12–14 days

• If gonorrhea culture positive → base treatment on susceptibility.
• If quinolone-resistant N. gonorrhoeae or susceptibility unknown → ID specialist consultation.

Special Situations

Follow-Up

• Expect clinical improvement (defervescence, reduced abdominal/uterine/adnexal/cervical motion tenderness) within 3 days.
• If no improvement within 72 hrs of oral/IM outpatient therapy → hospitalize, reassess regimen, consider diagnostic laparoscopy for alternative diagnoses.
• Retest all women (chlamydial or gonococcal PID) at 3 months post-treatment regardless of partner treatment status; if not feasible, retest whenever next seeking care within 12 months.

Management of Sex Partners

• Evaluate, test, and presumptively treat male partners from contact within 60 days preceding symptom onset for chlamydia and gonorrhea (regardless of identified pathogen).
• If last intercourse >60 days before symptoms → treat most recent partner.
• Partners often asymptomatic; use Expedited Partner Therapy (EPT) if linkage-to-care is delayed/unlikely.
• Advise abstinence until therapy completed and symptoms resolved in both patient and partner(s).

Prevention

• Screen/treat chlamydia & gonorrhea in sexually active women (proven to reduce PID incidence).
• BV treatment's role in preventing PID is unclear; role of screening for M. genitalium unknown.

5. Complications (for context/viva)

• Tubo-ovarian abscess
• Chronic pelvic pain
• Infertility (tubal factor)
• Ectopic pregnancy (tubal scarring)
• Fitz-Hugh-Curtis syndrome (perihepatitis with RUQ pain from C. trachomatis/N. gonorrhoeae spread — "violin-string" adhesions on liver capsule)
• Recurrent PID

Quick-recall diagnostic mnemonic

Note on recent literature