Ovarian cancer is diagnosed through a combination of pelvic exams, blood tests, imaging, and ultimately surgery to examine tissue under a microscope. No single test can confirm or rule out ovarian cancer on its own, so doctors use these tools in sequence to build a complete picture. A definitive diagnosis requires a tissue sample, which is why surgery plays a central role in the process.
The Pelvic Exam
A pelvic exam is often the first step when ovarian cancer is suspected. During the exam, a doctor inserts one or two gloved fingers into the vagina while pressing on the lower abdomen with the other hand. This allows them to feel the size, shape, and position of the uterus and ovaries. They’re checking for anything unusual: a mass, an enlarged ovary, or an area that feels irregular. A rectal exam may also be performed to check for lumps or abnormal areas from that angle.
Pelvic exams can detect larger masses, but they have real limitations. Small tumors and early-stage disease are easy to miss by touch alone. An abnormal finding on a pelvic exam doesn’t mean cancer is present, either. Many benign conditions, from ovarian cysts to uterine fibroids, can feel similar. That’s why a pelvic exam is a starting point, not an answer.
Blood Tests and Tumor Markers
The most commonly ordered blood test during an ovarian cancer workup is CA-125, a protein that tends to be elevated when ovarian cancer is present. Levels above 35 units per milliliter are generally considered abnormal. The problem is that CA-125 is not specific to ovarian cancer. It can be elevated by endometriosis, pelvic infections, liver disease, and even normal menstruation. It also misses a significant number of early-stage cancers, making it more useful for monitoring treatment than for catching the disease early.
Other tumor markers your doctor may order include CEA, CA 19-9, and CA 27-29. These help distinguish ovarian cancer from cancers that may have spread from other organs, like the colon or stomach.
Multi-Marker Panels
To improve on the limitations of CA-125 alone, two FDA-cleared blood panels combine multiple biomarkers into a single risk score. The ROMA (Risk of Ovarian Malignancy Algorithm) combines CA-125 with a protein called HE4 and factors in whether you’ve gone through menopause. In clinical testing, adding ROMA to a doctor’s initial assessment increased the ability to correctly identify cancer from about 77% to 91%, while also improving confidence that a negative result truly meant no cancer was present.
The OVA1 test takes a different approach, combining five biomarkers into one score. Both panels are designed for women who already have a pelvic mass and are being evaluated before surgery. They help determine whether that surgery should be performed by a gynecologic oncologist, which improves outcomes.
Imaging: Ultrasound, CT, and MRI
Ultrasound is typically the first imaging test ordered. A transvaginal ultrasound, where a small probe is inserted into the vagina, gives the clearest view of the ovaries. Doctors look for specific features that raise suspicion for cancer: irregular solid tumors, masses larger than 10 centimeters with both solid and fluid-filled areas, papillary projections (finger-like growths inside a cyst), free fluid in the pelvis, and strong blood flow within the tumor.
If the ultrasound findings are straightforward and there’s no concern about cancer spreading beyond the pelvis, an ultrasound alone may be sufficient before surgery. But when the picture is less clear, or when cancer seems likely, additional imaging is needed.
CT scans are the recommended imaging tool for staging ovarian cancer, meaning they help determine how far the disease has spread. A CT scan can reveal the size of the primary tumor, whether cancer has implanted on surfaces inside the abdomen (particularly the omentum, the fatty tissue that drapes over the intestines), and whether lymph nodes are enlarged. For detecting spread within the abdomen, CT picks up about 92% of cases in advanced disease.
MRI is particularly valuable when an ultrasound finding is indeterminate, meaning it’s not clearly benign or malignant. MRI with contrast has high specificity, which means it’s good at confidently identifying benign lesions and sparing patients from unnecessary surgery. Its sensitivity for detecting abdominal spread reaches about 95% in advanced cases, slightly outperforming CT.
Why Surgery Is Required for a Final Diagnosis
Unlike many other cancers, ovarian cancer is rarely diagnosed by needle biopsy. There are two reasons for this. First, needle biopsies of ovarian masses carry a risk of spilling cancer cells into the abdominal cavity, which could worsen the prognosis. Second, needle biopsies have high false-negative rates for certain tumors, meaning they can miss cancer that’s actually there. The internal structure of ovarian tumors matters for diagnosis, and a small needle sample often can’t capture enough tissue to classify the tumor accurately.
Instead, surgery serves as both the diagnostic and initial treatment step. A surgeon removes the mass (and often the affected ovary) and sends it to a pathologist, who examines the tissue under a microscope. This is the only way to confirm whether cancer is present, what type it is, and how aggressive it looks. During the same surgery, the surgeon typically explores the rest of the abdomen to check for spread, which determines the cancer’s stage.
Conditions That Mimic Ovarian Cancer
Part of the diagnostic process involves ruling out other conditions that can look remarkably similar on imaging or physical exam. Uterine fibroids, fluid-filled fallopian tubes, pelvic abscesses, and ovarian torsion (a twisted ovary) can all produce pelvic masses. Cancers from other organs, particularly colon cancer and stomach cancer, can spread to the ovaries and initially appear to be primary ovarian tumors. Even non-gynecologic issues like a distended bladder, fecal impaction, or a pelvic kidney can create confusion on imaging.
This is why the layered approach matters. Blood markers help narrow the origin. Imaging helps characterize the mass. But tissue examination is ultimately what separates benign from malignant and ovarian cancer from cancers that started elsewhere.
Genetic Testing After Diagnosis
Once ovarian cancer is confirmed, genetic testing becomes part of the workup. The Society of Gynecologic Oncology recommends that all patients with epithelial ovarian cancer (the most common type) be offered germline genetic testing. This tests your inherited DNA for mutations, particularly in the BRCA1 and BRCA2 genes, that may have contributed to the cancer developing.
The results matter for two reasons. First, certain mutations make tumors responsive to specific targeted therapies, which directly affects your treatment plan. Second, finding a hereditary mutation has implications for your blood relatives, who may benefit from increased screening or preventive measures. Somatic testing, which looks at mutations in the tumor itself rather than your inherited DNA, may also be performed to identify additional treatment options.