If I remember correctly from my application days, I think a small minority of U.S. medical schools actually explicitly require you to have a bachelor's degree. Most successful applicants have one by default of course but you won't be denied admission based on this factor alone.
I actually only had about 92 semester hours of undergrad completed by the time I entered medical school. In other words, I still had my whole "senior" year ahead of me. But since I took a "nontraditional" route, I think this was more readily overlooked. If you are following a straight path from HS,to college then med school, you will most likely need to be on track to graduate with a Bachelor's the spring prior to matriculation before gaining acceptance. Just what I've experienced and seen FWIW.