Pelvic or lower-abdominal pain in women most often traces to one of three things: pelvic inflammatory disease (PID), a sexually transmitted infection of the upper reproductive organs; a urinary tract infection (UTI); or an ovarian cyst. They overlap too much to tell apart by symptoms alone. A test settles which one it is, and PID needs prompt treatment to protect fertility.
of those who've had PID
chlamydia, gonorrhea
| Item | Value |
|---|---|
| US women with a history | ~2.5 million |
| Later infertility | ~1 in 8 — of those who've had PID |
| Main cause | untreated STIs — chlamydia, gonorrhea |
| Prevention | early testing |
The short list: what's likely causing pelvic pain
When the pain sits low in the abdomen or deep in the pelvis, three culprits cover most cases. One is an STI complication, the other two aren't. Quick triage before we get into how to tell them apart:
- PID — an infection of the uterus, fallopian tubes, and ovaries, usually a downstream complication of untreated chlamydia or gonorrhea.
- UTI — a bacterial infection of the bladder or urinary tract, the most common non-STI cause of this kind of pain.
- Ovarian cyst — a fluid-filled sac on the ovary that can cause pressure, aching, or sudden sharp pain if it ruptures or twists.
These conditions share so many symptoms, and several run silent, so you usually can't self-diagnose. This page maps the overlapping signals to the right diagnosis and tells you when to act fast.
Which STIs cause pelvic or lower-abdominal pain
The STI answer here is essentially one condition: pelvic inflammatory disease. Chlamydia and gonorrhea don't usually cause deep pelvic pain on their own. The pain shows up when those infections go untreated and climb upward into the reproductive tract.
Pelvic inflammatory disease (PID)
PID is an infection of the upper female reproductive organs — the uterus, fallopian tubes, and ovaries — often a complication of untreated STIs like chlamydia and gonorrhea CDC. Bacteria that started as a cervical infection migrate upward, inflaming the tubes and surrounding tissue. That inflammation produces the deep, aching pelvic pain people notice.
The tell-tale pattern is lower abdominal or pelvic pain combined with one or more of these: unusual discharge with a bad odor, fever, pain or bleeding during sex, burning when you urinate, and bleeding between periods. PID symptoms are often mild or absent, so many people don't realize they have it, and undiagnosed PID can scar the fallopian tubes before anyone knows it's there.
That scarring is why PID matters more than the others. Damaged tubes can lead to infertility, chronic pelvic pain, or ectopic pregnancy (a pregnancy that implants in the tube instead of the uterus, which is a medical emergency). Given those stakes, PID is treated on suspicion rather than proof.
When it's NOT an STI
Plenty of pelvic pain has nothing to do with sex. The two most common non-STI causes are easy to confuse with PID at first.
Urinary tract infection (UTI)
A UTI is a bacterial infection of the bladder or urinary tract, and a common non-STI source of lower-abdominal pain. The signature is urinary: burning with urination, needing to go often and urgently, and pressure low over the bladder. Cloudy or strong-smelling urine is typical. The pain tends to sit centrally above the pubic bone rather than off to one side, and there's usually no abnormal vaginal discharge unless something else is going on.
Ovarian cyst
An ovarian cyst is a fluid-filled sac on the ovary, another common non-STI cause of pelvic pain. Many cysts cause nothing at all. When they do hurt, it's often a dull ache or sense of fullness on one side, sometimes tied to the menstrual cycle. The pain can turn sudden and severe if a cyst ruptures or if the ovary twists on its stalk (ovarian torsion), a sharp one-sided pain that can come with nausea and is a reason to be seen right away.
How to tell them apart
No single symptom is decisive. These overlap too much to tell apart by sight alone, and several are silent. A few discriminating features point a clinician in the right direction:
- Where it hurts: UTI pain is central, over the bladder; ovarian-cyst pain is usually one-sided; PID pain tends to be deeper and felt across the lower pelvis.
- Discharge and odor: foul-smelling or unusual vaginal discharge leans toward PID; a UTI doesn't change vaginal discharge.
- Urinary clues: frequency, urgency, and burning with otherwise normal periods point to a UTI.
- Cervical-motion tenderness: pain when the cervix is moved during a pelvic exam is a hallmark of PID and is part of how clinicians decide to treat.
- Timing with the cycle: cyclical, one-sided pain near ovulation suggests a cyst; a sudden severe spike suggests rupture or torsion.
Overlapping symptoms are why you usually can't self-diagnose this. A test turns a guess into an answer.
Side-by-side comparison
| Feature | PID | UTI | Ovarian cyst |
|---|---|---|---|
| STI-related? | Yes — often from untreated chlamydia/gonorrhea | No | No |
| Pain location | Deep, across lower pelvis | Central, over the bladder | Usually one-sided |
| Vaginal discharge | Often unusual, foul-smelling | Normal | Normal |
| Urinary symptoms | Can include burning | Burning, urgency, frequency | Usually none |
| Fever | Possible | Possible if it spreads to kidneys | Uncommon unless rupture/torsion |
| Pain with sex | Common | Uncommon | Sometimes |
| Main risk if ignored | Tubal scarring, infertility, ectopic pregnancy | Kidney infection | Rupture or torsion |
How it's tested
Testing depends on what's suspected: a urine sample for a UTI, a self-collected or clinician swab for chlamydia and gonorrhea, and a pelvic exam — sometimes imaging — for PID or a cyst. There's no single confirmatory test for PID; it's diagnosed clinically CDC, 2021. You can get tested at a clinic or health department, and most STI results come back in a few days. If you're testing because of a specific exposure, check when to test after exposure so you don't test too early to catch it.
In practice it's a urine cup, a quick swab, or a brief exam. Testing is free or low-cost at health departments, Planned Parenthood, and Title X clinics.
What to do next
A confirmed UTI is treated with antibiotics aimed at the bladder. Most ovarian cysts resolve on their own and just need monitoring, though painful or large ones get follow-up imaging. PID is the one you don't wait on: the CDC advises a low threshold to treat, because waiting for confirmation risks permanent tubal damage. Treatment combines antibiotics that cover chlamydia, gonorrhea, and other bacteria, and any sex partners from the recent past should be tested and treated too. See the full regimen and timeline on the pid treatment page.
Red flags — when to get seen urgently
Some pelvic pain can't wait for a routine appointment. Seek care promptly if you have:
- Sudden, severe one-sided pelvic pain (possible cyst rupture or ovarian torsion).
- High fever with pelvic pain, which can signal a serious upper-tract infection.
- Severe pain with nausea, vomiting, or fainting.
- Pelvic pain with a positive or possible pregnancy — ectopic pregnancy is an emergency.
- Heavy or unusual vaginal bleeding alongside the pain.