Pelvic inflammatory disease (PID) is a complex inflammatory disorder of the female upper genital tract that usually develops as a result of an initiating sexually transmitted infection, but can also be caused by iatrogenic uterine instrumentation.16 The term denotes a wide spectrum of histopathologic entities including endometritis, salpingitis, oophoritis, peritonitis, and abscess formation. Clinically, PID can manifest in a wide range of symptoms, from subtle pelvic discomfort to frank peritonitis and hemodynamic shock. A distinct entity called subclinical PID has been recognized as an asymptomatic infection with evidence of upper genital tract inflammation; despite lack of symptoms, subclinical PID is suspected to result in the same long-term reproductive sequelae as its symptomatic counterpart.710

## Burden of Disease

Surveillance data suggest that lifetime prevalence of PID for women in the United States is 8%,1 with 20% of cases affecting adolescent females.11,12 Estimates of the true burden of this disease, though, are likely inaccurate because this syndrome is not reportable and is substantially underdiagnosed because of atypical presentations. Incidence is decreasing from a peak of 1 million cases annually in the early 1980s to 420,000 cases in the year 2001.6,11,13 Similarly, hospitalization rates have substantially decreased since 1980s, reflecting a shift to outpatient management. Total medical cost of PID was estimated at $2.7 billion for the year 1990,14 but because of the decreased incidence and hospitalization rates, total expenditure in 1998 was$1.88 billion, with long-term reproductive sequelae representing 40% of that sum.15

## Risk Factors

Demographic, behavioral, and contraceptive practices have been evaluated in cross-sectional studies as risk factors for PID (Table 43–1). Among demographic risk factors, age younger than 19 years,1618 lower socioeconomic group,16,19 non-Caucasian race,16,17,20 lack of married status,16,21 and less education17,22 have been associated with increased risk of PID. Behavioral risk factors overlap with those for acquiring STIs. High-risk behaviors include early sexual debut,16,18,19,23 having multiple sexual partners,2325 and having a current or past STI.16,1821,26 A history of PID is reported by some19 but not all17,18 authors as an independent risk factor for recurrence. Use of substances like alcohol,18,27 tobacco,17,19,22,28 and cocaine17 may also increase PID risk. Additionally, engaging in sex during menses19,24 and douching2931 are behaviors that remain controversially associated with PID.

Table 43–1. Risk Factors for PID

### Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.