Pelvic Inflammatory Disease (PID) Overview

PID is a bacterial infection of the uterus, ovaries, fallopian tubes, and other reproductive organs. The sexually transmitted infections gonorrhea and chlamydia are common causes of PID, although this condition can also be caused by other types of bacteria.¹ Oral antibiotics are generally used to treat mild cases of PID; severe cases may require hospitalization.²

Women with PID may have fever; chills; fatigue; unusual bleeding during their periods; or discharge from the vagina that has an unusual smell, color, or texture. This condition can also cause pain in the lower abdomen and pain during intercourse or urination.² Because PID can present with a wide variety of symptoms, accurately diagnosing this condition remains difficult. Identifying biomarkers for PID is a crucial component of addressing this diagnostic gap and improving patient care.

PID can leave scarring on reproductive organs that can lead to ectopic pregnancies, chronic pelvic pain, and abscesses. In the United States, PID is also the most common preventable cause of infertility.³

Age plays a role in the risk of PID, as it is most likely to occur in women aged 15 to 24 years old. The risk is also higher among those with multiple sex partners, those who have a sexually transmitted infection or who have had PID in the past, those who douche, and those who recently had an intrauterine device inserted.^{1 , 4}

Some cases of PID do not cause symptoms, but they can still have long-term effects on fertility.⁵ These "silent" or subclinical cases of PID are not well understood, and more research is needed to develop optimal management strategies for this type of PID. Likewise, research is currently lacking on the mechanisms behind PID cases that are not caused by sexually transmitted infections and the complex relationship between vaginal microbiota and PID development. The psychosocial impact of a PID diagnosis and the barriers to PID awareness and education also require further exploration.

As part of the National Institute of Allergy and Infectious Diseases (NIAID), the Division of Microbiology and Infectious Diseases (DMID) supports researchers who are searching for methods to treat and prevent diseases that are caused by infectious agents. Within DMID, the Enteric and Sexually Transmitted Infections Branch is studying sexually transmitted infections and the conditions that arise from these infections, including PID.⁶