Depends. Was your entire personal statement about this experience you can't seem to remember details about? It must have been inspirational enough to push you towards medicine after all. That being said no they won't ask about nitty gritty details. They're more likely to ask why you felt this experience was that important to you if they bring it up at all. Stories for personal statements are dime a dozen.
Oh I can absolutely explain why it was significant for me. No questions asked haha. If they asked me so well what did they do while this guy was bleeding out from almost every orifice after being brutally assaulted I'll have zero answer to that question.