Chapter 103: Pelvic Inflammatory Disease

INTRODUCTION AND EPIDEMIOLOGY

The term pelvic inflammatory disease (PID) comprises a spectrum of infections of the female upper reproductive tract. Although accurate estimates of the incidence and prevalence of PID in the United States are lacking due to lack of mandatory reporting and reliance on testing data, it is a common and serious disease initiated by ascending infection from the vagina and cervix. PID includes salpingitis, endometritis, myometritis, parametritis, oophoritis, and tubo-ovarian abscess and may extend to produce peri-appendicitis, pelvic peritonitis, and perihepatitis (Fitz-Hugh–Curtis syndrome). PID is the most common serious infection in sexually active women age 16 to 25 years.¹ In 2001, ambulatory data estimated that more than 750,000 cases of PID occurred in the United States.² The percentage of ED visits resulting in a diagnosis of PID decreased during 2006 to 2018 among females age 15 to 44 years (28.1% overall reduction, –4.3% annual change). Patients with less access to health care, including those without insurance or with public health insurance and those with lower median incomes, were the most likely to visit EDs.³

Long-term sequelae, including tubal factor infertility, implantation failure after in vitro fertilization, ectopic pregnancy, and chronic pain, may ultimately affect 11% of reproductive-aged women.⁴ The most common cause of death is rupture of a tubo-ovarian abscess, with mortality associated with rupture remaining at 5% to 10%, even with current treatment methods.

PATHOPHYSIOLOGY

ORGANISMS ASSOCIATED WITH PID

Neisseria gonorrhoeae and Chlamydia trachomatis can be isolated in many cases of PID, and therapy is largely directed against these organisms. Chlamydia has developed a number of mechanisms to avoid autophagy and destruction by the host immune system and is able to persist in a nonreplicative form in host epithelial cells.^5–7 Polymicrobial infection, including infection with anaerobic and aerobic vaginal flora, is evident from cultured material from the upper reproductive tract.⁸ Table 103-1 lists common pathogenic organisms associated with acute or subclinical PID. N. gonorrhoeae, C. trachomatis, and bacterial vaginosis–associated organisms are usually instrumental in initial infection of the upper genital tract. Approximately 15% of cases are due to enteric or respiratory organisms that have colonized the lower genital tract.² Anaerobes, facultative anaerobes, and other bacteria are isolated increasingly as inflammation develops and abscesses form.