I had surgery with Dr. McGinn a month ago, and went through 8 hour-long electrolysis sessions over a 3 month period before surgery (stopping 1 month before the operating date).
Dr. McGinn emphasized that, while she will scrape follicles of remaining hair in the surgical area, scraping is still only effective for hair that's in a growth cycle. However- she reassured that it's very typical for trans women to have *some* hair growing inside the vagina post op, and if coupled at least a few sessions of electrolysis, there very likely won't be enough hair to be noticed, or cause discomfort.
Anecdotally- the electrolysis isn't that bad! It was more painful on the face, tbh.
