Slightly different scenario but thought I'd pass it along. My 72 year old wife had a total knee replacement in July of 2024. She was diagnosed with ET/Jak2 in September but I'm sure she had ET during the surgery, she just wasn't on the Hydrea at the time. Her platelets at the time of surgery were 520,000 and had been steadily rising for more than a year. We didn't pick up the issue until further blood tests. The surgeon was aware of the platelet count but not sure what they did for anticoagulants during the surgery. I do know that she was told to be on a baby aspirin daily after the surgery.
Perhaps it would be prudent to have your surgeon reach out to your oncologist so they are both on the same page. ps. Surgery went well. She isn't running anymore, after a life time of marathons and half ironman tris but she is still very active. Best of luck on your surgery.