A 41-year-old woman undergoes exploratory laparotomy for a persistent adnexal mass. Frozen section diagnosis is serous carcinoma. Assuming that the other ovary is grossly normal, what is the likelihood that the contralateral ovary is involved in this malignancy?

Serous carcinoma is the most common epithelial tumor of the ovary. On histologic examination, psammoma bodies can be seen in approximately 30% of these tumors. Bilateral involvement characterizes about one-third of all serous carcinomas. Although mesonephroid carcinomas tend to be associated with pelvic endometriosis, a similar association has not been demonstrated for serous carcinomas.