It sounds as though you have a complex cyst that has been leaking some. Complex cysts are different from normal, functional cysts (which are a part of ovulation), but the majority of them are not cancer.
What does your doctor say? They can often get a good idea from the ultrasound if there is a cancer concern or not and can also check for cancer markers with a CA 125 blood test (helpful, but not 100% accurate). If there is little concern for cancer and you are not in major pain, they may choose to leave it alone and see if it resolves itself. However, if there is a cancer concern, or it is causing a lot of pain for you, they may choose to remove it. Also, complex cysts can grow very large, so they will likely monitor it, even if you choose not to remove it.
Do your research. The ovary does not always need to be removed and sometimes they seem to be removed more often than they should. Ask about the possibility of a cystectomy and ask for a second opinion if you're not comfortable with what your doctor says.
Hope this helps. Good luck!
I posted some links to your discussion over on the Ovarian Cancer board. Here is what a posted:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2815011/ -
Premature menopause or early menopause: long-term health consequences
"Premature menopause and early menopause, whether spontaneous or induced, are associated with long-term health risks which may include premature death, cardiovascular disease, neurologic disease, osteoporosis, psychosexual dysfunction, and mood disorders. Estrogen mitigates some but not all of these consequences."
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3804006/ - Reassessing Hysterectomy
"In summary, the removal of either ovary or of the uterus may have far-reaching health consequences. Therefore, the surgical removal of female reproductive organs should be considered carefully."
Most ovarian cysts, even complex ones, are benign (non-cancerous). If you do not have a predisposition or family history of ovarian cancer then your lifetime risk is VERY LOW (less than 2%).
Complex cysts sometimes resolve on their own but oftentimes have to be removed especially if they get too large (risk of ovarian torsion). Since the ovaries and uterus have LIFELONG functions and removal of any part can wreak havoc on hormones and long-term health, it is best to have just the cyst removed (cystectomy) allowing you to keep your ovary (or enough of it to regenerate).
I had a cyst similar to yours and my organs were needlessly removed (hysterectomy and oophorectomy). I wish I had known a lot more than I now know as I would have done things very differently. For starters, I would not have trusted my gynecologist nor the oncologist to whom he sent me for consultation. My surgeon sent the cyst tissue (frozen section) to pathology while I was under anesthesia. When it came back benign, he should have sewn me back up. Instead he proceeded to remove the rest of my sex organs. I know plenty of other women who have needlessly lost their uterus and/or ovary(ies). At least 90% of female sex organ removal surgeries are unwarranted.
So please do your research and advocate for what is in the best interests of your short and long-term health since you are the one who has to live with the consequences. Keep us posted on what you find out and recommended treatment. Good luck!