Pelvic inflammatory disease (PID) is an infectious and inflammatory disorder of the upper female reproductive tract, including the uterus, fallopian tubes, and adjacent pelvic structures. It is most commonly caused by ascending bacterial infection from the vagina and cervix, frequently associated with sexually transmitted pathogens such as Chlamydia trachomatis and Neisseria gonorrhoeae. Other potential microbial agents include anaerobic bacteria, Mycoplasma genitalium, and a polymicrobial mix of endogenous flora.
Signs and symptoms
Patients with PID may present with lower abdominal or pelvic pain, abnormal uterine bleeding, dyspareunia (painful intercourse), and vaginal discharge. Fever, chills, and malaise can accompany more severe cases. However, up to 50 % of affected individuals may be asymptomatic or experience mild, nonspecific symptoms, leading to delayed diagnosis.
Diagnostic evaluation
Diagnosis is based on a combination of clinical criteria and laboratory testing. The Centers for Disease Control and Prevention (CDC) recommends a minimum of three of the following: (1) cervical motion tenderness, (2) uterine tenderness, (3) adnexal tenderness, (4) temperature > 38 °C, (5) abnormal cervical or vaginal discharge, and (6) laboratory evidence of infection (e.g., positive nucleic acid amplification test for C. trachomatis or N. gonorrhoeae). Imaging such as transvaginal ultrasonography may be employed to assess for tubo‑ovarian abscesses or other complications. Laparoscopy can provide definitive visualization of inflamed or damaged pelvic structures but is not routinely required.
Management
Prompt antimicrobial therapy is essential to prevent long‑term sequelae such as infertility, chronic pelvic pain, and ectopic pregnancy. Recommended regimens typically combine a cephalosporin (e.g., ceftriaxone) with doxycycline, with or without metronidazole, to cover likely pathogens. In cases of severe disease, hospitalization, intravenous antibiotics, and possible surgical intervention (e.g., drainage of abscesses) are indicated. Patients should be advised to abstain from sexual activity until treatment is completed and symptom resolution is confirmed.
Epidemiology
PID is most prevalent among sexually active women of reproductive age, particularly those aged 15–24 years. Estimates suggest that 1–2 % of women in this age group develop PID annually in high‑income countries. Risk factors include multiple sexual partners, a history of sexually transmitted infections (STIs), early age of sexual debut, and intrauterine device (IUD) use, although the absolute risk associated with IUDs is low when proper screening is performed.
Prevention
Primary prevention focuses on reducing STI transmission through safe sexual practices, such as consistent condom use, routine screening for C. trachomatis and N. gonorrhoeae, and timely treatment of identified infections. Secondary prevention includes education on recognizing early symptoms and seeking prompt medical care. For women using IUDs, guidelines recommend STI screening before insertion and periodically thereafter.
Complications
If untreated or inadequately treated, PID can lead to permanent damage to the fallopian tubes (scarring and obstruction), resulting in infertility or an increased risk of ectopic pregnancy. Chronic pelvic pain and the formation of tubo‑ovarian abscesses are also recognized complications.
Prognosis
With early diagnosis and appropriate antibiotic therapy, most women recover without lasting reproductive impairment. However, the risk of subsequent infertility remains elevated, particularly after recurrent episodes or severe acute disease. Ongoing research aims to refine diagnostic criteria, improve treatment protocols, and reduce the global burden of PID.
