I'm a second-year undergrad student and I've done over 80 heart transplants on a pre-clinical porcine model. I was brought to a heart retrieval and the surgical staff asked me to scrub in to help him (this includes cutting, cautery, suction, and etc, basically a resident's job). I would have said no if there was a more qualified person in the room, but there wasn't and I was his best option to successfully retrieve the organ.
Legally speaking, since I worked at the hospital as a research staff, I'm covered by the hospital insurance. On top of that, the surgeon at the end of the day has the ultimate say in the OR because he/she/they have the ultimate liability for the case. If they feel like you are ready and skilled enough, they will ask you to scrub in and assist because they either a) need the help or b) would like to teach you because you're talented/have connections.
I would definitely say do it so you have a feeling of what it's like to be in an OR, but if it's not meaningful (like mentioned above), don't do write it on an application. Admission panels are usually composed of medical students, staff, and teaching staff, so they can easily see through your bs if you're useless; however, if it had a significant personal impact and case impact, then for sure: you should write about it on your application.