A biopsy is not usually conducted when ovarian cancer is suspected. Instead, a staging surgery is often performed. During surgery, tissue and fluid are removed from the pelvis and abdomen.

The surgery performed will depend on the symptoms, the size of the ovarian mass present, and the other findings on the workup. A laparotomy, or incision in the abdomen to access the pelvis, may be performed. Alternatively, a laparoscopy may be performed where the provider inserts a thin, lighted tube, called a laparoscope, through small incisions in the abdomen. Laparoscopy can be used to remove a small, benign cyst or an early ovarian cancer. It may also be used to determine whether cancer has spread.

The tissue removed is then examined by a pathologist using a microscope to look for cancer cells in the tissue or fluid. If ovarian cancer cells are found, the pathologist describes the grade of the cells. Grades 1, 2, and 3 describe how abnormal the cancer cells look. Higher grade cancer cells are more aggressive and more likely to spread.