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Pelvic Inflammatory Disease (PID)

BASICS

  • Definition: Infection of the upper female genital tract (uterus, fallopian tubes, ovaries, pelvic structures) usually due to ascending polymicrobial infection from the lower genital tract.
  • Severity:
  • Mild-moderate: Absence of tubo-ovarian abscess (TOA)
  • Severe: Severe systemic symptoms OR presence of TOA
  • Diagnosis: Clinical, often challenging due to nonstandardized definitions/symptoms; many patients have subtle/nonspecific signs.

EPIDEMIOLOGY

  • Most common in: Sexually active women <30 years old
  • Incidence: >1 million US cases annually
  • Lifetime prevalence: ~4.4% in sexually active women (18–44 yrs)
  • Disparity: Higher rates in Black women without STI history (suggests more undiagnosed STIs)

ETIOLOGY & PATHOPHYSIOLOGY

  • Polymicrobial: Chlamydia trachomatis, Neisseria gonorrhoeae (now <50% cases), Mycoplasma genitalium, anaerobes (e.g., Bacteroides fragilis), Gardnerella, E. coli, Haemophilus influenzae, etc.
  • Mechanisms of ascent:
  • Cervix → endometrium → salpinx → peritoneal cavity (most common)
  • Lymphatic spread (esp. IUD)
  • Rarely hematogenous
  • Complications: Infertility, chronic pelvic pain, ectopic pregnancy, TOA

RISK FACTORS

  • Age <25 years, new/multiple sexual partners, inconsistent condom use
  • Recent gynecologic procedures (e.g., IUD insertion, endometrial biopsy)
  • Prior PID, cervical ectopy, prior C. trachomatis or N. gonorrhoeae

GENERAL PREVENTION

  • Barrier contraception, annual chlamydia screening (<25 yrs & high-risk), safe sex education
  • Early treatment of genital lesions or abnormal discharge
  • Routine STI screening in pregnancy

COMMONLY ASSOCIATED CONDITIONS

  • IUD + pelvic abscess → suspect Actinomyces
  • Fitz-Hugh-Curtis syndrome (perihepatitis): severe RUQ pain, complicates 4–6% of PID
  • Ruptured adnexal abscess: rare, life-threatening

DIAGNOSIS

History

  • Lower abdominal/pelvic pain (dull, aching, bilateral, worsened by motion/coitus)
  • Abnormal vaginal discharge (~75%)
  • Fever, chills, cramping, dyspareunia, low back pain, urinary symptoms
  • Unanticipated vaginal bleeding (often postcoital)

Physical Exam

  • Fever, lower abdominal pain, cervical motion/uterine/adnexal tenderness, cervicitis, vaginal discharge

Differential Diagnosis

  • Appendicitis, ectopic pregnancy, ovarian torsion/tumor, hemorrhagic/ruptured cyst, endometriosis, IBD, diverticulitis, UTI/pyelo, nephrolithiasis

Tests

  • Initial:
  • Pregnancy test (rule out ectopic)
  • Chlamydia/gonorrhea NAAT/cervical swab
  • Urinalysis
  • Wet prep (WBC, BV, trichomoniasis)
  • HIV & syphilis screen
  • TVUS (hydrosalpinges, TOA, free fluid)
  • Follow-up: Serial US for abscess resolution
  • Laparoscopy: Only for unclear cases, treatment failures, or diagnostic uncertainty

TREATMENT

General

  • Treat empirically based on clinical suspicion—do not delay for lab results
  • Outpatient management for most, unless severe/complicated
  • IUD removal not required unless no improvement after 48–72h

First Line (Outpatient)

  • Ceftriaxone 500 mg IM x1 (if >150kg, 1g) PLUS
  • Doxycycline 100 mg PO BID x14d PLUS
  • Metronidazole 500 mg PO BID x14d
  • (CDC now recommends adding metronidazole to standard regimen)

Second Line

  • Cefoxitin 2g IM x1 + probenecid 1g PO x1 or cefotaxime 1g IM x1 or ceftizoxime 1g IM x1
  • PLUS doxycycline and metronidazole as above
  • Penicillin-allergic: Levofloxacin 500 mg PO BID x14d (if cephalosporin contraindicated)

Hospitalization (Inpatient) Indications

  • Surgical emergencies (appendicitis, etc.) not excluded
  • Pregnancy, TOA, severe illness, intolerance to PO meds, failed outpatient Rx after 72h
  • Parenteral regimens (CDC):
  • A: Ceftriaxone 1g IV q24h + doxycycline 100mg PO/IV q12h + metronidazole 500mg PO/IV q12h
  • B: Clindamycin 900mg IV q8h + gentamicin

  • C: Ampicillin/sulbactam 3g IV q6h + doxycycline

  • Parenteral therapy for 24–48h after improvement, then continue oral Rx to complete 14 days

Special Considerations

  • Refer/treat all sexual partners from last 60 days
  • Expedited partner therapy where available
  • HIV+ patients: treat as per general population

SURGERY/PROCEDURES

  • Reserved for treatment failures or suspected/ruptured abscesses

ONGOING CARE

  • Follow-up: At 72h (esp. moderate/severe), monitor for improvement
  • Test of cure for GC/CT at 3 months
  • Serial US for abscess monitoring
  • Education: Abstinence until treatment complete (patient/partner); encourage condom use, STI screening, HPV/Hep B vaccines, offer HIV PrEP if appropriate

PROGNOSIS

  • Complications:
  • Infertility (~18%)
  • Chronic pelvic pain (29%)
  • Ectopic pregnancy (0.6%); risk increases 7–10x
  • TOA (7–16% before presentation); 20–25% recurrence rate

  • Hydrosalpinx (infertility, pain)

  • Early Rx = Good prognosis; delayed Rx = higher risk of complications

ICD-10 Codes

  • N70.0 Acute salpingitis and oophoritis
  • N70 Salpingitis and oophoritis
  • N71.0 Acute inflammatory disease of uterus

CLINICAL PEARLS

  • PID is often polymicrobial; chlamydia/gonorrhea only in <50% cases now
  • Treat empirically in at-risk women with pelvic/lower abdo pain and CMT/adnexal/uterine tenderness
  • Infertility, ectopic pregnancy, chronic pain: major long-term sequelae
  • Hydrosalpinx, adhesions, TOA: major complications