What is pelvic inflammatory disease (PID)?

Pelvic Inflammatory Disease (PID)

Pelvic inflammatory disease is an infection-caused inflammatory condition of the female upper genital tract, including any combination of endometritis, salpingitis, tubo-ovarian abscess, and pelvic peritonitis, primarily resulting from ascending spread of microorganisms from the vagina and endocervix. 1

Etiology

PID has a polymicrobial etiology involving multiple organisms:

• Primary sexually transmitted pathogens:

  • Neisseria gonorrhoeae (cervical isolation rates 27-80%)
  • Chlamydia trachomatis (cervical isolation rates 5-39%)
  • Mycoplasma genitalium

• Secondary microorganisms (found in 25-50% of cases):

  • Anaerobes: Bacteroides, Peptostreptococcus, Peptococcus species
  • Facultative bacteria: Gardnerella vaginalis, Streptococcus species, Escherichia coli, Haemophilus influenzae
  • Other: Mycoplasmas, bacterial vaginosis-associated organisms 1, 2

Pathogenesis

PID develops through:

1. Direct canalicular spread of organisms from the endocervix to the endometrium and fallopian tubes
2. Noncanalicular spread via parametrial lymphatics (less common)

Contributing factors to ascending infection:

• Uterine instrumentation (e.g., IUD insertion)
• Hormonal changes during menses (reduced cervical barrier function)
• Retrograde menstruation
• Organism-specific virulence factors 1

Clinical Presentation

PID presents with a wide spectrum of symptoms, making diagnosis challenging:

• Common symptoms: Lower abdominal pain, abnormal vaginal discharge
• Additional symptoms: Metrorrhagia, postcoital bleeding, urinary frequency, fever
• Important note: Many women (particularly those with chlamydial PID) may have subtle, mild, or even no symptoms 3, 2

Diagnosis

The clinical diagnosis of PID is imprecise, with a positive predictive value of 65-90% compared to laparoscopy. Due to the risk of serious sequelae, a low threshold for diagnosis is recommended 1.

Minimum criteria for clinical diagnosis:

• Lower abdominal tenderness
• Bilateral adnexal tenderness
• Cervical motion tenderness 1

Additional supportive criteria:

• Routine criteria:

  • Oral temperature >38.3°C (101°F)
  • Abnormal cervical/vaginal discharge
  • Elevated WBCs on vaginal secretion microscopy
  • Elevated ESR or C-reactive protein
  • Laboratory documentation of cervical infection with N. gonorrhoeae or C. trachomatis 1

• Elaborate criteria (for severe cases):

  • Histopathologic evidence of endometritis
  • Tubo-ovarian abscess on imaging
  • Laparoscopic findings consistent with PID 1

Treatment

Early administration of appropriate antibiotics is crucial to reduce the risk of long-term sequelae 3. Treatment should provide broad-spectrum coverage against likely pathogens.

Outpatient treatment (mild-to-moderate PID):

• Extended-spectrum cephalosporin PLUS either doxycycline or azithromycin 4, 2
• Patients should show substantial improvement within 72 hours; if not, reevaluation, hospitalization, and parenteral therapy are indicated 1

Inpatient treatment (severe PID):

• Indications for hospitalization:

  • Severe symptoms
  • Tubo-ovarian abscess
  • Pregnancy
  • Inability to tolerate oral medications
  • Failure to respond to oral therapy 1

• Parenteral broad-spectrum antibiotics with activity against polymicrobial flora, particularly gram-negative aerobes and anaerobes 4, 2

• May switch to oral therapy 24 hours after clinical improvement, completing a total of 14 days of treatment 1

Partner Management

• Male sex partners should be examined and treated if they had sexual contact with the patient during the 60 days before symptom onset
• This is critical due to the risk of reinfection and the high likelihood of urethral gonococcal or chlamydial infection in partners 1

Complications and Sequelae

PID can lead to serious long-term consequences:

• Infertility (tubal factor)
• Ectopic pregnancy
• Chronic pelvic pain
• Recurrent PID
• Tubo-ovarian abscess 5, 6

Prevention

• Regular screening for chlamydial and gonococcal infections in sexually active women
• Prompt treatment of cervicitis and bacterial vaginosis
• Consistent condom use
• Reduction in number of sexual partners 1

Key Points for Clinicians

• Maintain a low threshold for diagnosis due to the potential for serious sequelae
• Begin treatment promptly when PID is suspected
• Consider PID in sexually active women with pelvic or lower abdominal pain, even with mild symptoms
• Remember that many cases of PID may be asymptomatic or present with subtle symptoms
• Ensure appropriate partner treatment to prevent reinfection