Pelvic Inflammatory Disease

Lydia A. Shrier

DEFINITION

Pelvic inflammatory disease (PID) is an ascending polymicrobial infection of the female upper genital tract and includes endometritis, parametritis, salpingitis, oophoritis, tuboovarian abscess (TOA), peritonitis, and perihepatitis.

ETIOLOGY

Risk Factors

Age: Adolescent and young adult (AYA) women account for up to one-third of cases of PID; the peak incidence is among 20- to 24-year-olds.¹
- Cervical ectropion: The erythematous ring around the cervical os, commonly seen in adolescents, is the transitional zone between the columnar and squamous epithelium and is highly susceptible to sexually transmitted infections (STIs).
- Cervicitis with Neisseria gonorrhoeae or Chlamydia trachomatis: Among women with gonococcal or chlamydial cervicitis, approximately 10% to 20% develop PID, with higher rates being reported among high-risk adolescents.²
- Sexual and other health-risk behaviors: AYAs who frequently engage frequently engage in behaviors associated with increased rates of STIs and PID, including unprotected and/or frequent intercourse, multiple sex partners, intercourse during menses, smoking, alcohol, and other drug use.³
- Age at first intercourse: Risk for PID is more common among women who had coitarche before the age of 15 or 16 years.³
Previous PID: A history of previous PID increases the risk of subsequent PID.³,⁴
Race: Black AYAs have an increased risk of PID compared to non-Black AYAs.³,⁵
Contraceptive methods
- Condoms: Inconsistent use is associated with two to three times the risk of PID.⁶
- Oral contraceptives: Associated with increased risk of infection with chlamydia, and possibly gonorrhea,⁷ but not with risk of PID.⁶
- Medroxyprogesterone acetate: May reduce the risk of PID,³ although the association has not been consistently observed.⁶
- Intrauterine device (IUD): The risk of PID following insertion of the current generation of IUDs is low, even in the presence of cervicitis,⁸ and generally restricted to the first 3 weeks after insertion.
Bacterial vaginosis (BV): May facilitate ascension of organisms pathogenic for PID to the upper genital tract. Anaerobic bacteria associated with BV have been found in the upper genital tract of women with acute PID,⁹ but longitudinal studies have not consistently supported an association between BV and subsequent PID.¹⁰,¹¹
Menses: May be associated with increased risk of ascending infection because of cervical mucus plug loss, endometrial shedding, menstrual blood (a good culture medium), and/or myometrial contractions, resulting in reflux of blood into the fallopian tubes.

Microbiology

PID is a polymicrobial infection. N. gonorrhoeae and C. trachomatis have been identified in the lower or upper genital tract in up to two-thirds of PID cases¹²; adolescents with PID are more likely than adults to be infected with these organisms.¹³ PID also involves genital mycoplasmas, and aerobic and anaerobic bacteria comprising endogenous vaginal flora.

N. gonorrhoeae: Found in the upper and/or lower genital tract of 11% to 33% of women with PID⁹,¹⁴,¹⁵,¹⁶ and associated with a dramatic presentation.¹⁷
C. trachomatis: Recovered from the upper and/or lower genital tract in up to 44% of women with PID.⁹,¹⁴,¹⁵,¹⁶ Chlamydial PID presents more subtly than gonococcal PID, which may delay care, contributing to worse reproductive health outcomes.¹⁸
Genital mycoplasmas (Mycoplasma genitalium, Mycoplasma hominis, Ureaplasma urealyticum): M. genitalium has been found in the upper and/or lower genital tract of 7% to 14% of women with nongonococcal, nonchlamydial PID¹⁴,¹⁹ and may be more common among women <25 years of age.²⁰
Bacteroides species and other anaerobes: More than 60% of women with PID have evidence of upper tract infection with anaerobic organisms.²¹
Other endogenous vaginal flora (Escherichia coli, Haemophilus influenzae, Streptococcus species, and other facultative bacteria).

Pathogenesis

Following lower tract infection, commonly with N. gonorrhoeae or C. trachomatis, anaerobes, facultative bacteria, and genital mycoplasmas supplant vaginal lactobacilli.
Inflammatory disruption of the cervical barrier facilitates ascension of the inciting pathogens and other microorganisms from the vagina into the normally sterile uterus.
Decreased tubal motility secondary to inflammation results in collection of fluid (hydrosalpinx) or pus (pyosalpinx) within the tube.
Spillage of infected contents from the tubes into the peritoneal cavity may result in the following:
- Peritonitis
- Perihepatitis (Fitz-Hugh-Curtis syndrome): Infected material tracks along the paracolic gutter. Inflammation of the hepatic capsule and diaphragm causes right upper quadrant pain and referred right subscapular pain. Perihepatitis is relatively uncommon in adolescents with PID (4%²² to 7%¹⁶).
- TOA: Develops if resolution of upper tract infection is delayed or if previous tubal scarring occludes the tube. The abscess can form in the tube or between the tube and ovary. TOA may be found in 26% of hospitalized adolescents,²³ but rates may be much lower among adolescents treated as outpatients.²⁴ Incidence of TOA in young adult women with PID has not been reported separately from that in older women.
- Adhesions: Scar tissue in the tube, between the tube and ovary, or in the peritoneal cavity leads to infertility, ectopic pregnancy, and chronic abdominal or pelvic pain.

PRESENTING SIGNS AND SYMPTOMS

The classic presentation—lower abdominal or pelvic pain, abnormal vaginal and/or cervical discharge, fever and chills, leukocytosis, and increased erythrocyte sedimentation rate (ESR)—is seen in only approximately one in five laparoscopically verified cases of PID. Subclinical infection likely accounts for most cases.