Prevalence of Pelvic Inflammatory Disease in Sexually Experienced Women of Reproductive Age — United States, 2013–2014

Pelvic inflammatory disease (PID) is a clinical syndrome of the female reproductive tract characterized by inflammation of the endometrium, fallopian tubes, or peritoneum (1). PID occurs when microorganisms ascend from the vagina or cervix to the fallopian tubes and other upper genital tract structures (1). PID can result from untreated bacterial infections, including chlamydia and gonorrhea, and can lead to infertility, ectopic pregnancy, and chronic pelvic pain (1). Because there is no single diagnostic test for PID, clinicians rely on nonspecific signs and symptoms for diagnosis. The purpose of these analyses was to assess the burden of self-reported PID in a nationally representative sample using data from the National Health and Nutrition Examination Survey (NHANES) 2013–2014 cycle. Starting in 2013, NHANES female participants aged 18–44 years were asked about a lifetime history of PID diagnosis. Based on these data, the estimated prevalence of self-reported lifetime PID was 4.4% in sexually experienced women of reproductive age (18–44 years). The prevalence of self-reported lifetime PID was highest in women at increased risk, such as women reporting a previous sexually transmitted infection (STI) diagnosis. Stratified by race/ethnicity and having a previous STI diagnosis, non-Hispanic black (black) and non-Hispanic white (white) women reporting a previous STI diagnosis had nearly equal self-reported lifetime PID prevalence (10.0% versus 10.3%). However, the lifetime prevalence of PID among black women was 2.2 times that among white women if no previous STI was diagnosed (6.0% versus 2.7%). These findings suggest that PID is prevalent and associated with previous STI diagnoses; therefore, it is important for clinicians to screen female patients for chlamydia and gonorrhea to reduce the incidence of PID.

NHANES is a cross-sectional, complex, multistage survey designed to be nationally representative of the noninstitutionalized U.S. civilian population (https://www.cdc.gov/nchs/nhanes.htm). Participants undergo a medical examination and are interviewed in person, during which time questions regarding sexual and reproductive health are asked. In NHANES 2013–2014, a total of 1,444 women aged 18–44 years were interviewed and had a medical exam; the response rate was 71.1%. The 1,171 (81%) reproductive-aged female participants who responded “Yes” to the question, “Have you ever had vaginal, anal, or oral sex?” were defined as sexually experienced and were the focus of these analyses. Participants who responded “Yes” to the question, “Have you ever been treated for an infection in your fallopian tubes, uterus or ovaries, also called a pelvic infection, pelvic inflammatory disease, or PID?” met the case definition of a lifetime PID diagnosis. Having received a diagnosis of a previous STI was defined as having had a chlamydia or gonorrhea infection during the past 12 months or ever having had herpes, human papillomavirus, or genital warts. The prevalence of self-reported lifetime PID, prevalence ratios (PRs), and 95% confidence intervals (CIs) were estimated overall and by various characteristics. Associations were measured by use of the Rao-Scott chi-square test. All analyses were conducted using SAS statistical software (version 9.3) and accounted for the complex survey design and sampling weights. As such, these results are nationally representative. The mobile examination center exam sampling weights were used to weight the data. Population counts were estimated by multiplying weighted prevalence estimates by the average of the American Community Survey estimates during 2013–2014.

Among 1,171 sexually experienced reproductive-aged women in NHANES 2013–2014, the prevalence of self-reported lifetime PID was 4.4% (Table), indicating that approximately 2.5 million women aged 18–44 nationwide have received a diagnosis of PID in their lifetime (95% CI = 1.8–3.2 million). No significant differences existed in prevalence of a lifetime PID diagnosis by age, race/ethnicity, or socioeconomic factors, such as income-poverty ratio, current health insurance coverage, or having a current usual place for health care.

Significant differences in the prevalence of lifetime PID were observed by the sexual behaviors and sexual health histories of respondents. The prevalence of self-reported lifetime PID among women whose age of sexual debut was <12 years was approximately eight times that of women whose age of sexual debut was ≥18 years (PR = 8.6). Similarly, the lifetime PID prevalence among women with ≥10 lifetime male vaginal sex partners was approximately three times that of women with a single partner (PR = 3.6). The prevalence of lifetime PID was approximately double in women reporting lesbian/bisexual versus heterosexual orientation (PR = 2.1), and the prevalence among women reporting a previous STI diagnosis was approximately three times that of women without a previous STI diagnosis (PR = 3.3).

In stratified analyses (Figure), the prevalence of self-reported lifetime PID among women reporting a previous STI diagnosis was similar in whites and blacks (10.0% [95% CI = 4.4–15.6] versus 10.3% [95% CI = 1.3–19.4], p = 0.97). However, among women with no previous STI diagnosis, the prevalence of self-reported lifetime PID in black women was 2.2 times the prevalence in white women (black: 6.0% [95% CI: 3.4–8.6] versus white: 2.7% [95% CI: 1.1–4.4], p = 0.01).

Corresponding author: Kristen Kreisel, ltq1@cdc.gov, 404-718-5148.

¹Division of STD Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, CDC.

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TABLE. Prevalence of self-reported lifetime pelvic inflammatory disease* among sexually experienced women^† aged 18–44 years (n = 1,171), by selected characteristics — National Health and Nutrition Examination Survey, United States, 2013–2014.

Abbreviations: CI = confidence interval; ED = emergency department; FPL = Federal Poverty Level; GED = General Educational Development certification; HMO = health maintenance organization; NC = not calculated; STI = sexually transmitted infection.
* Prevalence estimates based on response to the question “Have you ever been treated for an infection in your fallopian tubes, uterus or ovaries, also called a pelvic infection, pelvic inflammatory disease, or PID?”
^† Based on a response of “Yes” to the question “Have you ever had vaginal, anal, or oral sex?”
^§ Estimates were weighted to be nationally representative of the U.S. population, accounting for unequal probabilities of selection and nonresponse.
^¶ Respondents with missing or unknown values were excluded from prevalence ratio calculations.
** Calculated via use of the Rao-Scott chi-square test. The overall p-values could not be calculated (p = NC) for some characteristics with zero prevalence in categories not shown (e.g., “other” category for sexual orientation).
^†† Relative standard error >30% but <40%.
^§§ Relative standard error >50%; estimates are suppressed.
^¶¶ Relative standard error >40% but <50%.
*** Ratio of family income to poverty level as defined by the U.S. Census Bureau.
^††† Participants who were told by a doctor or other health care professional in the last 12 months that they had chlamydia or gonorrhea or were ever told they have herpes, human papilloma virus, or genital warts.

FIGURE. Prevalence of self-reported lifetime pelvic inflammatory disease* among sexually experienced women^† aged 18–44 years (n = 1,171), by race/ethnicity and previous STI diagnosis^§,¶ — National Health and Nutrition Examination Survey, United States, 2013–2014

Abbreviation: STI = sexually transmitted infection.

* Prevalence estimates based on response to the question, “Have you ever been treated for an infection in your fallopian tubes, uterus or ovaries, also called a pelvic infection, pelvic inflammatory disease, or PID?” Estimates were weighted to be nationally representative of the U.S. population, accounting for unequal probabilities of selection and nonresponse.

^† Based on a response of “Yes” to the question, “Have you ever had vaginal, anal, or oral sex?”

^§ Participants who were told by a doctor or other health care professional in the last 12 months that they had chlamydia or gonorrhea or were ever told they have herpes, human papilloma virus, or genital warts.

^¶ Bars indicate 95% confidence interval. Prevalence estimates among non-Hispanic black women with a previous STI diagnosis have a relative standard error >40% but <50%.