Description

• Pelvic inflammatory disease (PID) is an infection of the upper female genital tract, including the uterus, fallopian tubes, ovaries, and adjacent pelvic structures. PID is most commonly an ascending polymicrobial infection acquired through retrograde movement of microorganisms from the lower genital tract (1)[C].
• PID is clinically concerning due to its consequences for future fertility.
• Mild to moderate PID is characterized by the absence of a tubo-ovarian abscess (TOA). Severe disease is defined as severe systemic symptoms OR the presence of a TOA (2)[C].
• Diagnosis may be challenging due to nonstandardized definitions and guidelines, lack of a single definitive diagnostic test, and variation in signs and symptoms. Many patients with PID have subtle or nonspecific symptoms (2)[C].

Epidemiology

Most commonly affects sexually active patients aged <30 years

Incidence
More than one million patients are diagnosed with PID annually (1)[C].

Prevalence
Estimated prevalence of lifetime PID is 4.4% in sexually active cisgender women aged 18 to 44 years. Approximately 2.5 million women of reproductive age in the United States have had a PID diagnosis.

• Lifetime prevalence has decreased steadily since 1995.
• Without history of prior STI, lifetime prevalence is higher in black versus white women (6% vs. 2.7%). Among patients with a prior STI, lifetime prevalence was similar across race (10% vs. 10.3%). This disparity suggests black patients might be more likely to have had an undiagnosed STI, subsequently developing PID.

Etiology and Pathophysiology

Multiple organisms cause PID, and polymicrobial infections are common.

• Chlamydia trachomatis and Neisseria gonorrhoeae, previously thought to be the most commonly implicated pathogens in PID, are now identified in only 22–50% of cases (2)[C]. Genital tract mycoplasmas (particularly Mycoplasma genitalium) have similar incidence rates as C. trachomatis in recent studies of patients with PID, although their role in the pathophysiology of PID is unclear.
• Common flora and causes of bacterial vaginosis including aerobic and anaerobic (Bacteroides fragilis) species and vaginal microbes (e.g., Prevotella, peptostreptococci, Gardnerella vaginalis, Escherichia coli, Haemophilus influenzae) are increasingly implicated (2)[C].
• Possible mechanisms for ascent from the lower genital tract include (i) travel from cervix to endometrium to salpinx to peritoneal cavity; (ii) lymphatic spread via infection of the parametrium (from an IUD); and (iii) hematogenous route, although this is rare.

Risk Factors

• Sexually active and age <25 years
• New sexual partner or sexual partner with symptoms or a known diagnosis of STI
• Two or more sexual partners within the last year
• Inconsistent condom use
• Gynecologic procedures that break the cervical barrier such as endometrial biopsy, curettage, hysterosalpingography, hysteroscopy, in vitro fertilization, and insertion of IUD in the last 3 weeks (3)[C]
• Other factors associated with PID:
  • Previous history of PID; 20–25% will have a recurrence.
  • Cervical ectopy
  • History of C. trachomatis; 10–40% will develop PID.
  • History of gonococcal cervicitis; 10–20% will develop PID.

General Prevention

• Educational programs about safe sex practices such as barrier contraceptives, especially condoms.
• The U.S. Preventive Services Task Force recommends annual screening for chlamydia in all sexually active women aged <25 years and in those aged ≥25 years at increased risk (new sex partner/multiple sex partners). Moderate-quality evidence suggests that chlamydia screening reduces cases of PID (3)[C].
• Routine STI screening in pregnancy
• Early medical care with the occurrence of genital lesions or abnormal discharge

Commonly Associated Conditions

• In a patient with an IUD and a pelvic abscess, suspect Actinomyces infection requiring penicillin treatment.
• Rupture of an adnexal abscess is rare but is life-threatening. Early surgical exploration is mandatory (2)[C].
• Chlamydial or gonococcal perihepatitis, called Fitz-Hugh-Curtis (FHC) syndrome, may occur with PID. FHC syndrome is characterized by severe pleuritic right upper quadrant pain and complicates 4–6% of PID cases (2)[C].