Pelvic inflammatory disease (PID) is an infection of the upper reproductive organs, including the uterus, fallopian tubes, and ovaries. It develops when bacteria travel upward from the vagina or cervix into these deeper structures, triggering inflammation that can cause lasting damage if not treated promptly. PID is one of the most common serious infections in women of reproductive age, and it’s also one of the most preventable.
How PID Develops
The vagina and cervix naturally harbor bacteria, and the cervix acts as a barrier that keeps most of those organisms from reaching the upper reproductive tract. PID occurs when that barrier is breached, usually by sexually transmitted bacteria, and infection spreads into the uterus, fallopian tubes, or ovaries. Once bacteria reach these tissues, the immune system responds with inflammation, swelling, and sometimes abscess formation.
About half of PID cases involve gonorrhea or chlamydia. But PID isn’t always caused by a single organism. In many cases, a mix of bacteria is responsible, including organisms that normally live in the vagina without causing problems. These bacteria can become harmful when they migrate to areas where they don’t belong. This means PID can develop even in someone who tests negative for the most commonly screened STIs.
Who Is Most at Risk
PID can affect anyone with a uterus who is sexually active, but it’s most common in women under 25. Several factors raise the likelihood:
- Current or past STI, especially gonorrhea or chlamydia
- Multiple sexual partners, or a partner who has other partners
- Previous episode of PID, which makes recurrence more likely
- Frequent douching, which may push bacteria upward and disrupt the vagina’s natural balance
Age plays a role partly because the cervix in younger women is still maturing and may be more susceptible to infection. Behavioral factors like inconsistent condom use compound that biological vulnerability.
Symptoms and What They Feel Like
PID symptoms range from barely noticeable to severe. Many women experience a dull, persistent ache in the lower abdomen or pelvis. Pain during sex is common, particularly with deep penetration. Other typical signs include unusual vaginal discharge (often with an odor), irregular bleeding or spotting between periods, burning during urination, and fever.
The tricky part is that PID can also be “silent.” Some women have no symptoms at all, or symptoms so mild they attribute them to a menstrual cramp or a urinary issue. This is one reason the infection sometimes goes untreated long enough to cause damage to the fallopian tubes.
When Inflammation Spreads Beyond the Pelvis
In a small number of cases, infection or inflammation from PID travels beyond the reproductive organs and reaches the tissue surrounding the liver. This is called Fitz-Hugh-Curtis syndrome. It produces sharp pain in the right upper abdomen, under the ribs, that worsens with breathing or movement. Because the pain is nowhere near the pelvis, it’s often mistaken for a gallbladder or liver problem. The inflammation creates sticky, string-like adhesions that attach the liver capsule to the abdominal wall or diaphragm, which is what causes the distinctive pain pattern.
How PID Is Diagnosed
There’s no single test that definitively confirms PID. Diagnosis is primarily clinical, meaning it’s based on your symptoms, medical history, and a physical exam. During a pelvic exam, your provider will check for tenderness in the uterus, fallopian tubes, and cervix. Pain or tenderness during this exam, combined with lower abdominal pain, is typically enough to begin treatment rather than waiting for lab results.
Additional tests help support the diagnosis and identify the specific bacteria involved. These may include cervical swabs for gonorrhea and chlamydia, blood tests to check for signs of infection, and a pregnancy test to rule out an ectopic pregnancy, which can cause similar symptoms. Transvaginal ultrasound can also be helpful. In one study, ultrasound detected thickened, fluid-filled fallopian tubes with 85 percent sensitivity and 100 percent specificity, making it a reliable tool when the clinical picture is uncertain.
Treatment and What to Expect
PID is treated with antibiotics, and most cases can be managed with oral medications taken at home. Because PID is often caused by a mix of different bacteria, treatment typically involves a combination of antibiotics rather than a single drug. The full course usually lasts 14 days, and it’s important to finish the entire course even if symptoms improve within a few days. Stopping early can allow surviving bacteria to regrow and cause a relapse.
More severe cases, such as those involving a pelvic abscess, high fever, vomiting that prevents keeping oral medication down, or pregnancy, may require hospitalization for intravenous antibiotics. Surgery is rarely needed but can become necessary if an abscess doesn’t respond to antibiotics alone.
Your sexual partner (or partners) should also be evaluated and treated, even if they have no symptoms. Men can carry the bacteria that cause PID without any signs of infection, and untreated partners are a major reason PID recurs. Avoiding sex until both you and your partner have completed treatment helps prevent reinfection.
Long-Term Complications
The biggest concern with PID is the damage it can do to the fallopian tubes. Inflammation causes scarring and adhesions inside the tubes, which can partially or completely block them. This creates two serious risks: infertility and ectopic pregnancy, where a fertilized egg implants in the tube instead of the uterus.
A large cohort study tracking women from 2008 to 2022 found that those with chlamydia infections, a leading cause of PID, had roughly 2.8 times the risk of tubal factor infertility and 1.8 times the risk of ectopic pregnancy compared to women who tested negative. These risks climb with repeated episodes of PID. A single episode may cause relatively minor scarring, but each subsequent infection compounds the damage.
Chronic pelvic pain is another common aftermath. Even after the infection clears, adhesions and scar tissue can cause ongoing discomfort that lasts months or years. Some estimates suggest that roughly one in three women with a history of PID develops chronic pelvic pain.
Prevention
Consistent condom use is the most effective way to reduce your risk. Because chlamydia and gonorrhea are the two most common triggers, regular STI screening matters, especially if you’re under 25 or have new or multiple partners. Chlamydia in particular often causes no symptoms, so screening catches infections that would otherwise go unnoticed and potentially progress to PID.
If you’re diagnosed with chlamydia or gonorrhea, prompt treatment with the full course of antibiotics significantly lowers the chance of the infection ascending into the upper reproductive tract. Avoiding douching also helps maintain the vagina’s protective bacterial balance and reduces the chance of pushing harmful organisms upward.