How ovarian cancer is diagnosed
Ovarian cancer is diagnosed through a combination of physical exam, imaging, and blood tests—not through a single test that gives a yes-or-no answer. A doctor usually starts by asking about symptoms (pelvic pain, bloating, changes in bowel habits) and doing a pelvic exam to feel for masses. If something seems abnormal, the next step is almost always a transvaginal ultrasound, which uses a probe inserted into the vagina to get a close look at the ovaries. If the ultrasound shows a concerning cyst or mass, a blood test for a protein called CA-125 may follow, though this test alone cannot diagnose cancer.
The only way to know for certain whether a growth is cancer is a biopsy—a tissue sample taken during surgery or through a needle. Most women do not have a biopsy until imaging and blood work suggest cancer is likely. Surgery to remove the ovary or take a sample is both diagnostic and often the first treatment step, so the pathology report from that surgery is usually when a diagnosis is confirmed.
Key Takeaways
- Transvaginal ultrasound is the standard first imaging test when a doctor suspects ovarian cancer based on symptoms or a pelvic exam.
- CA-125 blood tests can suggest cancer is present but cannot diagnose it on their own, and results vary based on menstrual cycle, other conditions, and even benign ovarian cysts.
- A tissue biopsy is the only definitive way to diagnose ovarian cancer, and it usually happens during surgery to remove the affected ovary.
- Staging—determining how far the cancer has spread—requires CT or MRI imaging of the abdomen and pelvis, and sometimes a chest X-ray or PET scan.
The physical exam and symptom history
The diagnostic process begins in the office. Your doctor will ask detailed questions about when symptoms started, how often they occur, and whether anything makes them better or worse. They will perform a pelvic exam, inserting two gloved fingers into the vagina while pressing on the abdomen with the other hand to feel the size, shape, and texture of the ovaries. A normal ovary is about the size of an almond; anything larger or with an irregular surface raises concern.
This exam alone cannot diagnose cancer—many benign cysts and fibroids feel abnormal—but it tells the doctor whether imaging is needed. If the ovaries feel normal but symptoms persist, the doctor may still order imaging if the symptoms are severe or have lasted several weeks. If the exam finds a mass or the ovary feels hard or fixed in place, imaging becomes urgent.
Transvaginal ultrasound and what the images show
Transvaginal ultrasound is the imaging test ordered first because it gives the clearest view of the ovaries and uses no radiation. A technician inserts a probe about the size of a tampon into the vagina and moves it to see the ovaries from different angles. The ultrasound machine creates images in real time, and the technician takes still pictures to send to a radiologist for review.
The radiologist looks for specific features that suggest cancer: a cyst with thick walls, solid areas inside the cyst, multiple cysts on the same ovary, or fluid in the pelvis. A simple, thin-walled cyst with clear fluid inside is almost always benign. A complex cyst—one with solid nodules, thick septa, or irregular borders—raises suspicion. The radiologist assigns a risk score based on these features. If the score suggests cancer is possible, your doctor will order blood work and likely refer you to a gynecologic oncologist (a surgeon who specializes in cancer of the female reproductive system).
CA-125 blood test and what the results mean
CA-125 is a protein that can be elevated in ovarian cancer, but it is also elevated in many other conditions: endometriosis, fibroids, menstruation, pregnancy, liver disease, and even some infections. A single CA-125 result is not diagnostic. Doctors use it as one piece of information alongside imaging and symptoms.
A normal CA-125 level is generally below 35 units per milliliter, though this varies slightly by lab. A level above 35 in a woman with a suspicious ovarian mass on ultrasound increases the likelihood that cancer is present. However, some women with early ovarian cancer have normal CA-125 levels, and some with benign cysts have elevated levels. If CA-125 is very high (over 1,000), cancer becomes more likely, but imaging and biopsy are still needed to confirm. Your doctor may order CA-125 again after a few weeks to see whether the level is rising, which suggests a more urgent problem.
Biopsy and surgical diagnosis
A biopsy is tissue examined under a microscope by a pathologist, and it is the only way to definitively diagnose ovarian cancer. There are two ways to obtain tissue: needle biopsy or surgical biopsy. A needle biopsy uses imaging to guide a needle into the mass and withdraw cells; it can be done in an outpatient setting but is less common for ovarian masses because the ovary is deep in the pelvis and the sample is sometimes too small to be conclusive.
Most often, diagnosis happens during surgery. If imaging and blood work suggest cancer is likely, your gynecologic oncologist will recommend surgery to remove the ovary (or both ovaries) and examine the tissue. During surgery, the surgeon also looks at the lining of the abdomen, the lymph nodes, and other organs to see whether cancer has spread. Tissue samples from the ovary and any suspicious areas are sent to pathology. The pathology report comes back in a few days to a week and confirms whether cancer is present, what type it is, and how aggressive it appears under the microscope.
Staging scans after diagnosis
Once a biopsy confirms ovarian cancer, imaging is done to determine the stage—how far the cancer has spread. This staging process uses CT (computed tomography) scans of the abdomen and pelvis, which show whether cancer is present in the lymph nodes, liver, or other organs. A chest X-ray or chest CT may also be ordered because ovarian cancer can spread to the lungs and the lining around the lungs.
Some doctors order a PET scan (positron emission tomography), which uses a radioactive tracer to highlight areas where cancer cells are active. PET is more sensitive than CT for finding small deposits of cancer but is not always necessary for staging. The combination of surgical findings (what the surgeon saw and removed during the operation) and imaging results determines the stage, which ranges from Stage 1 (cancer confined to the ovary) to Stage 4 (cancer spread to distant organs). Staging guides treatment decisions and prognosis.
When symptoms lead to diagnosis
Many women are diagnosed with ovarian cancer only after symptoms have been present for weeks or months. Common symptoms include persistent pelvic or abdominal pain, bloating that does not go away, feeling full quickly when eating, and changes in bowel or bladder habits. Because these symptoms are vague and can be caused by many conditions, ovarian cancer is often diagnosed at a later stage than it would be if caught by screening.
There is no routine screening test for ovarian cancer in women without a family history or genetic risk. Women with a strong family history of ovarian or breast cancer, or who carry a BRCA1 or BRCA2 mutation, may be offered regular ultrasounds and CA-125 testing, though the benefit of this screening is not yet proven. If you have persistent symptoms that your primary care doctor cannot explain, asking for a referral to gynecology or a gynecologic oncologist is reasonable, especially if symptoms have lasted more than a few weeks.
Frequently Asked Questions
Can a Pap smear detect ovarian cancer?
No. A Pap smear screens for cervical cancer, not ovarian cancer. It samples cells from the cervix, not the ovaries. Ovarian cancer cannot be detected by a Pap smear.
What does it mean if my ultrasound shows a cyst but my CA-125 is normal?
A simple cyst with a normal CA-125 is usually benign and does not require immediate action. Your doctor may recommend a follow-up ultrasound in 6 to 12 weeks to confirm the cyst has not changed. Complex cysts or cysts that grow over time warrant closer follow-up or referral to a specialist, even with normal CA-125.
How long does it take to get a diagnosis after the first ultrasound?
If imaging suggests cancer is likely, your doctor will refer you to a gynecologic oncologist, which may take one to three weeks depending on availability. Surgery and biopsy typically happen within two to four weeks of that referral. The pathology report usually comes back within a week of surgery.
Can ovarian cancer be diagnosed without surgery?
A needle biopsy can sometimes diagnose ovarian cancer without surgery, but it is less common because the sample may be too small or inconclusive. Most diagnoses are confirmed during surgery, which also allows the surgeon to assess how far the cancer has spread and remove affected tissue.
What if my doctor thinks it is cancer but the biopsy says it is benign?
Benign ovarian masses are common and include cysts, fibroids, and teratomas. If the biopsy confirms the mass is benign, no cancer treatment is needed. Your doctor will discuss whether the mass should be removed, left alone, or monitored with follow-up imaging.