Hello,
I agree with the recommendation to remove that one ovary. if it is malignant, then the standard of care is to remove the right ovary and tube as well and to remove the uterus and check biopsies to look for spread. As most cysts are benign, the question arises, should you have your other ovary removed as a prophylactic measure.
If you have evidence of endometriosis at the time of your surgery, then you should consider removing the other ovary and uterus.This is because there is a small but increased risk of malignant change in the setting of endometriosis. If everything looks perfect, it becomes an individual decision.
There is no screening test for ovarian cancer. However, genetic testing for two genes, BRCA1 and BRCA 2 , are available. If your are considering not removing the other ovary if it looks normal, you should ask about genetic testing. However, your mother should be tested first. If she has the gene mutation that we presently can test for, then you and your sister need to get tested. If she does not have the gene mutation, it does not make sense for your to be tested at this time.
As for hormone replacement therapy, there is no hard data to suggest one form of estrogen therapy is better than another. There are alot of products out there so it can be an individual choice. You should ask your gyn what she thinks. At age 40, if you decide to have your ovaries removed, you should consider estrogen replacement to help with sexual function, vaginal dryness, hot flashes, bone strength.
Finally you can always go back later for more surgery. If you are having trouble making a decision, just have the one ovary removed for now.
best wishes to you.