Detailed definition
Oophorectomy refers to surgical removal of one (unilateral) or both (bilateral) ovaries. Bilateral oophorectomy is performed for risk reduction in BRCA1/2 mutation carriers, for ovarian cancer treatment, for severe endometriosis, and historically as part of routine hysterectomy for benign disease (a practice now generally discouraged in premenopausal women without specific indication). Bilateral salpingo-oophorectomy (BSO) adds removal of the fallopian tubes, useful given that many "ovarian" cancers actually originate in the distal fallopian tube. Removing both ovaries before natural menopause produces immediate, severe estrogen withdrawal and abrupt loss of the ovarian testosterone contribution. Women under 45 who undergo bilateral oophorectomy without HRT have higher long-term risks of cardiovascular disease, osteoporosis, cognitive decline, and earlier mortality. Major societies recommend HRT until at least the average age of natural menopause for these women, absent contraindications.
Why it matters in menopause
Bilateral oophorectomy in a premenopausal woman is almost always a strong indication for HRT — barring specific contraindications. Many women undergoing risk-reducing BSO for BRCA mutations are concerned about HRT and breast cancer; the risk-benefit math typically favors HRT in this population through the average menopause age.