Non-Sexually Transmitted Infection (STI)-Related Pelvic Inflammatory Disease (PID)

Pelvic inflammatory disease (PID), although traditionally viewed as a sexually transmitted infection (STI), can also result from non-sexually transmitted microorganisms that display distinct epidemiologic and clinical characteristics. Unlike STI-related PID, these infections are less influenced by sexual behavior, often show a bimodal age distribution, and are linked to bacterial vaginosis (BV)-associated dysbiosis, iatrogenic uterine procedures, postpartum states, or inadequate access to timely screening and care. Non-STI-related PID is usually polymicrobial, predominantly involving BV-associated vaginal, enteric, or urinary commensals that ascend into the upper genital tract, while respiratory tract organisms, mycobacteria, and biofilm-associated pathogens may also play a role. Pathophysiological mechanisms include disruption of the endocervical barrier, mucus degradation, biofilm formation, hematogenous or iatrogenic seeding, and chronic cytokine-mediated inflammation and fibrosis. Clinical manifestations range from asymptomatic/subclinical disease to acute pelvic pain and tubo-ovarian abscess (TOA) and can progress to systemic infection and sepsis. Diagnosing non-STI PID is challenging due to nonspecific symptoms, negative STI tests, and inconclusive imaging findings, while management relies on broad-spectrum antimicrobials with surgery as needed. Given these complexities, this review aims to synthesize current knowledge on non-STI-related PID, clarify key considerations for its diagnosis, management, and prevention, and outline future perspectives to improve clinical outcomes.