Pelvic Inflammatory Disease (PID) and NIH Women's Health Research

Signs, Symptoms, and Risk Factors

PID is a bacterial infection of the uterus, ovaries, fallopian tubes, and other reproductive organs. The sexually transmitted infections (STIs) gonorrhea and chlamydia are common causes of PID, although this condition can also be caused by other types of bacteria.¹

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

Age plays a role in the risk of PID, as it is most likely to occur in girls and women aged 15 to 24 years. The risk is also higher among those with multiple sex partners, those who have an STI or who have had PID in the past, those who douche, and those who recently had an intrauterine device inserted.^{1 , 3}

Diagnosis and Treatment

Because PID can present with a wide variety of symptoms, accurately diagnosing this condition remains difficult.

It is diagnosed using a combination of medical history, symptoms, physical examination findings, and diagnostic tests because no single test can definitively confirm the condition.¹ During the evaluation, a health care provider may perform a pelvic examination to look for signs such as cervical discharge, cervical tenderness, or pain. Laboratory tests may be used to assess infection or inflammation and to test for STIs, while imaging studies such as pelvic ultrasound or computed tomography (CT) scans can help identify complications or rule out other causes of symptoms.^{1 , 2}

Treatment typically involves prompt antibiotic therapy, which is often started before test results are available to reduce the risk of complications.^{1 , 2} People with mild PID may be treated with a combination of injectable and oral antibiotics, whereas those with severe disease, pregnancy, tubo-ovarian abscess, or persistent symptoms may require hospitalization, intravenous antibiotics, or, in some cases, surgery.² Early treatment is critical because 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.⁴

Ongoing Research

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 STIs 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 STIs and the conditions that arise from these infections, including PID.⁶