What tests detect ovarian cancer

There is no single test that reliably screens for ovarian cancer in people without symptoms. When doctors suspect ovarian cancer based on symptoms or findings during a pelvic exam, they typically order a combination of tests: a blood test for a protein called CA-125, an ultrasound of the pelvis, and sometimes a CT scan. If these tests suggest cancer, a biopsy—removing a small sample of tissue to examine under a microscope—is the only way to confirm the diagnosis.

The challenge with ovarian cancer detection is that early-stage disease often causes no symptoms, and the tests available are not sensitive enough to catch it reliably in asymptomatic people. This is why ovarian cancer is often found at a later stage, when symptoms have already appeared.

Key Takeaways

  • CA-125 blood tests and pelvic ultrasounds are the main tools doctors use when ovarian cancer is suspected, but neither test alone can confirm cancer.
  • A biopsy—taking tissue directly from the ovary or suspicious area—is required to confirm an ovarian cancer diagnosis.
  • CT or MRI scans help doctors see whether cancer has spread beyond the ovaries before treatment begins.
  • Routine screening for ovarian cancer in people without symptoms or risk factors is not recommended because current tests are not reliable enough.
  • People with a family history of ovarian or breast cancer may be offered genetic testing and more frequent monitoring.

CA-125 blood test and what it measures

CA-125 is a protein that can be elevated in ovarian cancer, but it is also elevated in many benign conditions—endometriosis, fibroids, menstruation, and other cancers. A single CA-125 result does not diagnose or rule out ovarian cancer. Doctors use it as one piece of information alongside imaging and symptoms.

The test is most useful in people already diagnosed with ovarian cancer, where a rising CA-125 level over time can signal that cancer is returning or that treatment is not working. In people without a diagnosis, an elevated CA-125 prompts further testing but does not mean cancer is present.

Pelvic ultrasound and what it shows

An ultrasound uses sound waves to create images of the ovaries and surrounding structures. A technician moves a probe over the lower abdomen (transabdominal ultrasound) or inserts a small probe into the vagina (transvaginal ultrasound) to get a closer view. The images can show whether an ovary is enlarged, whether there are cysts or solid masses, and whether fluid is present in the pelvis.

Ultrasound cannot definitively prove cancer is present—many benign cysts and masses appear on ultrasound. However, certain features (a solid component, thick walls, or irregular shape) raise concern and lead to further testing. Transvaginal ultrasound is more sensitive than transabdominal ultrasound for detecting ovarian abnormalities because the probe sits closer to the ovaries.

CT and MRI scans for staging and spread

If ultrasound and CA-125 suggest ovarian cancer, a CT (computed tomography) scan or MRI (magnetic resonance imaging) is usually ordered. These scans create detailed cross-sectional images and help doctors determine whether cancer has spread to the lymph nodes, liver, lungs, or peritoneum (the lining of the abdominal cavity).

CT is faster and more widely available; MRI provides better soft-tissue detail in some cases. Neither scan can diagnose ovarian cancer on its own, but both are essential for understanding the extent of disease before surgery or treatment begins. The results guide decisions about whether surgery should happen first or whether chemotherapy should start before surgery.

Biopsy: the only way to confirm diagnosis

A biopsy is the only test that can definitively confirm ovarian cancer. There are several ways to obtain tissue. During a procedure called fine-needle aspiration, a thin needle is guided by ultrasound or CT into a suspicious area and a few cells are withdrawn. A core needle biopsy uses a slightly larger needle to remove a small cylinder of tissue. Both can be done in an outpatient setting.

If imaging suggests advanced disease, the biopsy may happen during surgery. A surgeon removes the ovary, fallopian tube, or other affected tissue, and a pathologist examines it under a microscope to confirm cancer and determine its type and grade. In some cases, surgery itself is both diagnostic and therapeutic—it removes the cancer while confirming the diagnosis.

Genetic testing for hereditary risk

People with a personal or family history of ovarian cancer, breast cancer, or pancreatic cancer may carry mutations in genes like BRCA1 or BRCA2 that significantly increase cancer risk. Genetic testing involves a blood test that looks for these mutations. A positive result does not mean cancer is present—it means risk is elevated.

If you carry a BRCA mutation, your doctor may recommend more frequent screening with ultrasound and CA-125, or preventive surgery to remove the ovaries. Genetic counseling before and after testing helps you understand what results mean for your health and your relatives. Testing is most useful if you have a known family history or if you have already been diagnosed with ovarian cancer.

Why routine screening is not recommended

Major medical organizations including the American Cancer Society and the U.S. Preventive Services Task Force do not recommend routine ovarian cancer screening in people without symptoms or known risk factors. The reason is that available tests—CA-125 and ultrasound—are not sensitive or specific enough. They produce too many false alarms (abnormal results that turn out not to be cancer) and may miss some cancers.

Screening can lead to unnecessary biopsies and surgery in people without cancer, causing harm without benefit. For people at average risk, the best approach is to report any persistent pelvic pain, bloating, difficulty eating, or urinary symptoms to your doctor promptly. These symptoms warrant testing even though they are often caused by benign conditions.

Frequently Asked Questions

Can a CA-125 test alone tell me if I have ovarian cancer?

No. CA-125 can be elevated in ovarian cancer, but it is also elevated in many benign conditions and other cancers. A single elevated CA-125 result is not a diagnosis. Doctors use it alongside ultrasound, imaging, and symptoms to decide whether further testing is needed.

What should I do if my ultrasound shows a cyst on my ovary?

Most ovarian cysts are benign and resolve on their own. Your doctor will determine whether the cyst needs follow-up imaging based on its size, appearance, and your age and symptoms. Many cysts require only repeat ultrasound in a few weeks or months, not immediate biopsy.

If I have a family history of ovarian cancer, should I get screened?

Routine screening is still not recommended even with family history, but you should discuss your risk with your doctor. You may be a candidate for genetic testing to check for BRCA mutations, and if positive, for more frequent monitoring or preventive measures. Your doctor can help determine what makes sense for your situation.

Does a biopsy hurt, and how long does it take?

A needle biopsy is usually done under local anesthesia and takes 15 to 30 minutes. You may feel pressure or mild discomfort but not pain. A surgical biopsy is done under general anesthesia and takes longer, but you are asleep during the procedure. Recovery varies depending on the type of biopsy.

What happens after a biopsy confirms ovarian cancer?

Your doctor will order additional imaging (CT or MRI) to determine the stage and extent of cancer. You will likely meet with a gynecologic oncologist, a surgeon who specializes in cancer of the reproductive organs, to discuss treatment options, which may include surgery, chemotherapy, or both.