There is no single test that definitively diagnoses ovarian cancer. Instead, testing follows a sequence: blood work to check tumor markers, imaging to examine the ovaries, and, if a suspicious mass is found, surgery to collect tissue for a final diagnosis under a microscope. Routine screening is not recommended for women at average risk, so most testing begins after symptoms appear or an abnormal finding turns up during a pelvic exam.
Why There’s No Routine Screening
The U.S. Preventive Services Task Force gives ovarian cancer screening a grade of D for women without a known high-risk hereditary cancer syndrome. That’s the lowest recommendation, meaning the evidence shows screening causes more harm than benefit in the general population. The core problem is false positives. In large clinical trials, between 0.2% and 3.25% of screened participants ended up having surgery for a positive result that turned out not to be cancer. Up to 15% of those women experienced major surgical complications.
This doesn’t mean testing is useless. It means testing is reserved for women who have symptoms, a pelvic mass discovered on exam, or a strong family history that puts them in a higher-risk category.
Blood Tests: CA-125 and HE4
The most widely used blood marker for ovarian cancer is CA-125, a protein shed by ovarian tumor cells. The normal reference range is 0 to 35 units per milliliter. Levels above that threshold raise suspicion, but a high CA-125 alone does not confirm cancer. Many non-cancerous conditions push CA-125 up: endometriosis does so in about 88% of cases, cirrhosis in 40 to 80%, acute pelvic inflammatory disease in roughly a third, and even early pregnancy in up to 24%. Between 0.6% and 1.4% of healthy individuals have mildly elevated CA-125 with nothing wrong at all.
A second marker called HE4 helps fill in the gaps. HE4 tends to stay normal in many of the benign conditions that inflate CA-125, making the two markers more useful together than either one alone. Doctors often combine both markers with menopausal status in a calculation called the ROMA score (Risk of Ovarian Malignancy Algorithm). The result places a woman with a pelvic mass into either a high-risk or low-risk category for malignancy, which guides decisions about the next steps.
Transvaginal Ultrasound
Transvaginal ultrasound is the primary imaging tool. A small probe inserted into the vagina produces detailed images of the ovaries and surrounding structures. The test itself takes about 15 to 30 minutes and is not painful for most women, though it can feel uncomfortable.
Radiologists look at several features to judge whether a mass looks concerning or harmless. Signs that lean toward cancer include an irregular solid tumor, four or more finger-like projections (papillary structures) growing inside a cyst, a large irregular mass with both solid and fluid-filled areas (especially over 10 cm), and the presence of free fluid in the abdomen. Signs that lean toward a benign cyst include a simple fluid-filled sac with thin walls, no internal blood flow, and a smooth surface smaller than 10 cm.
Color Doppler, which maps blood flow, adds another layer. Malignant tumors often recruit new, disorganized blood vessels in the center of the mass, producing strong blood flow with low resistance. Benign masses tend to have blood flow only at the edges or none at all. A standardized system called IOTA Simple Rules helps doctors apply these criteria consistently so that fewer women are sent for unnecessary surgery.
Additional Imaging: CT and MRI
If ultrasound findings are suspicious, a CT scan of the abdomen and pelvis is typically the next step. CT helps determine whether cancer has spread beyond the ovaries to the lymph nodes, liver surface, or lining of the abdomen. MRI is sometimes used when ultrasound results are ambiguous, because it can distinguish between different types of tissue inside a mass with greater precision. Neither scan replaces the need for a tissue sample, but both help surgeons plan the operation and stage the disease.
Surgical Biopsy: The Only Definitive Test
The only way to confirm ovarian cancer is to remove tissue and examine it under a microscope. Unlike many other cancers, doctors generally avoid using a needle to biopsy a suspicious ovarian mass through the skin or abdomen. Puncturing the cyst wall risks spilling cancer cells into the abdominal cavity, which could spread the disease.
For masses that appear to be early-stage, the standard approach is surgery to remove the affected ovary and fallopian tube. A pathologist examines the tissue during or after the procedure to determine whether it is cancerous, what type of ovarian cancer it is, and how aggressive it looks. In more advanced cases where imaging already shows widespread disease, a diagnostic laparoscopy (a minimally invasive procedure using a small camera) can be used to take biopsies from multiple sites. This helps confirm the diagnosis and determines whether the cancer can be surgically removed in one operation or whether chemotherapy should come first to shrink the tumors.
Genetic Testing
Genetic testing plays two distinct roles in ovarian cancer: assessing inherited risk before cancer develops, and guiding treatment after a diagnosis.
For risk assessment, testing focuses on changes in the BRCA1 and BRCA2 genes. Women who inherit a harmful change in either gene face a significantly higher lifetime risk of ovarian cancer compared to the general population. Expert groups recommend genetic testing for women who have a family member with a known BRCA change, Ashkenazi Jewish heritage, a personal or family history of breast cancer before age 50, or a family history of ovarian, pancreatic, or aggressive prostate cancer. A genetic counselor typically reviews these factors before any test is ordered.
After an ovarian cancer diagnosis, tumors are often tested for BRCA changes and other genetic markers because the results can determine eligibility for targeted therapies. If a BRCA change shows up in the tumor itself, the next question is whether the patient inherited it or whether it arose only in the cancer cells. That distinction matters for the patient’s relatives, who may want to know their own risk.
What Symptoms Prompt Testing
Because there is no effective screening program, recognizing symptoms is the most common path to diagnosis. The symptoms are notoriously vague, which is part of why ovarian cancer is often caught at later stages. Persistent bloating that doesn’t come and go with your menstrual cycle, feeling full quickly when eating, pelvic or abdominal pain, and needing to urinate more frequently or urgently are the four most commonly reported. “Persistent” is the key word. These symptoms happen to nearly everyone occasionally. When they are new, occur almost daily, and last more than two to three weeks, that pattern warrants a visit to your doctor, who can order a CA-125 and ultrasound as a first step.