Biopsy
The only way to determine for certain if a growth is cancer is to remove a sample of the growth from the suspicious area and examine it under a microscope. This procedure is called a biopsy. For ovarian cancer, the biopsy is most commonly done by removing the tumor.
In rare cases, a suspected ovarian cancer may be biopsied during a laparoscopy procedure or with a needle placed directly into the tumor through the skin of the abdomen. Usually the needle will be guided by either ultrasound or CT scan. This is only used in patients who cannot have surgery because of advanced cancer or some other serious medical condition, because there is concern that a biopsy could spread the cancer..
In patients with ascites (fluid buildup inside the abdomen), samples of the fluid can also be used to diagnose the cancer. In this procedure, called paracentesis, the skin of the abdomen is numbed and a needle attached to a syringe is passed through the abdominal wall into the fluid in the abdominal cavity. The fluid is sucked up into the syringe and then sent for analysis in order to determine if it contains cancer cells.
In all these procedures, the tissue or fluid obtained is sent to the laboratory. There it is examined under the microscope by a pathologist, doctors who specialize in diagnosing and classifying diseases by examining cells under a microscope and using other lab tests.