Pelvic inflammatory disease (PID) is not itself a sexually transmitted disease, but it is most often caused by one. PID is an infection of the uterus, fallopian tubes, or ovaries that develops when bacteria travel upward from the cervix or vagina. Chlamydia and gonorrhea are the most common triggers, though infections that have nothing to do with sex can cause PID too.
The distinction matters because PID is a complication of infection, not something you “catch” directly from another person. You can’t pass PID to a partner. But if your PID was triggered by chlamydia or gonorrhea, those underlying infections are highly contagious and your sexual partners need to be tested and treated.
How STIs Lead to PID
Chlamydia and gonorrhea are the two STIs most closely linked to PID. Both infections start in the cervix and can silently climb into the upper reproductive tract if left untreated. Because chlamydia in particular often causes no symptoms at all, many people don’t realize they have it until PID develops weeks or months later.
Not every case of chlamydia or gonorrhea turns into PID. But the longer an STI goes untreated, the greater the chance that bacteria will spread beyond the cervix. This is one reason routine STI screening matters so much, especially for sexually active women under 25, who have the highest rates of both chlamydia and PID.
Non-Sexual Causes of PID
STIs get most of the attention, but PID can also develop from bacteria that are normally found in the vagina. An overgrowth of certain vaginal bacteria can push infection into the upper reproductive tract, particularly when the cervix is briefly opened during a medical procedure. The risk of PID is highest in the first 20 days after an IUD insertion, for example, at roughly 9.7 infections per 1,000 women per year during that narrow window. After those initial weeks the risk drops sharply to about 1.4 per 1,000.
Douching, which disrupts the natural balance of vaginal bacteria, has also been linked to a higher risk. In short, anything that shifts the vaginal environment or introduces bacteria past the cervix can set the stage for PID, with or without sexual contact.
Recognizing the Symptoms
PID symptoms range from barely noticeable to severe. The most common sign is dull pain or tenderness in the lower abdomen or pelvis. Some people also experience:
- Unusual vaginal discharge, sometimes with an unpleasant odor
- Pain during sex, particularly deep penetration
- Irregular bleeding, including spotting between periods
- Burning with urination
- Fever, typically above 101°F in more serious cases
Mild PID can feel like vague pelvic discomfort that’s easy to dismiss. That’s a problem, because even low-grade infection can damage the fallopian tubes over time. If you have persistent pelvic pain, especially combined with abnormal discharge or a recent STI diagnosis, getting evaluated promptly can prevent the complications described below.
Why Early Treatment Matters
PID is treated with antibiotics, typically a combination that covers both chlamydia and gonorrhea along with other bacteria that may be involved. Most people can take the full course at home in pill form. More severe cases, particularly those involving a high fever or a suspected abscess on the ovary or fallopian tube, may need IV antibiotics in a hospital setting.
The critical point is timing. Antibiotics can clear the active infection, but they cannot reverse scarring that has already formed inside the fallopian tubes. Each episode of PID adds cumulative damage. After a single infection, roughly 13% of women develop tubal blockage. After two infections that number jumps to about 36%, and after three or more it reaches 75%. This scarring is the main reason PID is one of the leading preventable causes of infertility.
Long-Term Risks of Untreated PID
The scarring left behind by PID creates three major long-term risks. The first is tubal factor infertility. Blocked or damaged fallopian tubes prevent an egg from reaching the uterus, making natural conception difficult or impossible. The second is ectopic pregnancy, where a fertilized egg implants inside a scarred fallopian tube instead of the uterus. Women with a history of PID have roughly twice the risk of ectopic pregnancy compared to women without PID. The third is chronic pelvic pain, which can persist for months or years after the infection itself has resolved.
Research from a large population-based study in Taiwan found that PID also nearly doubled the risk of preterm labor, at about 1.9 times higher than in women without a PID history. These risks compound with repeated infections, which is why preventing reinfection is just as important as treating the first episode.
Protecting Yourself and Your Partners
Because STIs are the most common pathway to PID, the same strategies that prevent chlamydia and gonorrhea also prevent most cases of PID. Consistent condom use significantly reduces risk. Annual chlamydia screening for sexually active women under 25 catches infections before they have a chance to climb into the upper reproductive tract.
If you’re diagnosed with PID, any sexual partners from the past 60 days should be tested and treated for chlamydia and gonorrhea, even if they have no symptoms. This prevents reinfection once you finish your own antibiotics. Avoid sex entirely until you and your partner have both completed treatment and your symptoms have resolved. Repeat STI testing three months after treatment helps confirm the infection hasn’t returned.