I am sorry you are dealing with this. I was in your shoes also at age 49 (now 62). A u/s done by my gynecologist of 20 years showed a 9cm cystic mass. I had always trusted and respected my doctor so when he mentioned that there was a chance of ovarian cancer (although I have no family history) and said I needed surgery quickly, I trusted him. He even took a step further saying there was not time to consult an oncologist but he would have one "standing by" to assist if cancer was found. The fear instilled by him clouded my judgment. It made me dismiss my intuition about his treatment plan and research the wrong things making for a devastating life-altering bad decision. I deeply regret it on a daily basis.
Instead of researching ovarian cancer, I wish I had researched the lifelong importance of the female organs and how removal of any one part does more harm than good regardless of our age. I knew that hysterectomy was overused but did not understand all the repercussions of having one's uterus removed - bladder and bowel displacement and dysfunction, sexual dysfunction, figure changes and ensuing back and hip problems due to the severing of the ligaments (pelvic support structures), endocrine dysfunction since the ovaries are endocrine glands that produce hormones a woman's whole life. And there is a whole other list of increased health risks and reduced quality of life when both ovaries are removed. And removal of one ovary can cause all the same problems. There are numerous studies on the problems caused by "bilateral oophorectomy" (castration) and some on "unilateral oophorectomy".
My gyn should have removed JUST the cyst (cystectomy) and sent it for frozen section while I was under anesthesia. Instead, he removed my ovary, sent it for frozen section and waited. When it came back benign, he continued to remove organs - my other ovary, uterus and tubes.
My life quickly fell apart. Within just 4 months, I aged 15-20 years because I lost about 75% of my hair, lots of skin collagen / subcutaneous fat and the front section of my hair turned gray. It probably didn't help that my bowels were screwed up (had diarrhea for over a year post-op).
Based on my connections with hundreds of women, the unnecessary removal of female organs is a "standard of care" despite the compelling medical evidence of the harm. So it can take a bit of searching to find a surgeon you can trust AND that has the skills to do organ sparing procedures WHEN surgery is necessary (e.g., cystectomy for cyst removal, myomectomy for fibroids). It is easier and quicker and therefore more profitable to remove the ovary or the uterus versus the growth. In all other specialties, they remove the growth, not the organ! But gynecology continues to treat our vital female parts as disposable. :(
Are you even sure your cyst is an endometrioma and not a hemorrhagic cyst? They have similar traits and cannot always be differentiated. Hemorrhagic cysts resolve on their own. However, the size of yours may be a concern for ovarian torsion. Radiographics articles may be helpful. Ovaries for Live (overy.org) is an excellent resource with a link to many studies about the harms of ovary removal. The HERS Foundation has some helpful info on their site too.
If you do end up needing surgical removal, seek out a surgeon with good cystectomy skills. According to a renowned surgeon who advocates for myomectomy and cystectomy, there are very few cases where the ovary needs to be removed.
I apologize for the novel but hope it helps! Please keep us posted on how this plays out. I hope you can enjoy your overseas vacation - how exciting!