Typically, conferences last for an average of 3 days; sometimes they last for a week, other times for a single day. Medical conferences often call for business casual style. Consider the weather at the conference site, and if you want to pack a carry-on or to check in your luggage, as the packing rules are different and may affect how you pack.
Clothing
Toiletries (check with the TSA for rules if flying)
Essentials
Technology