Does everyone need to buy BIG panties post-op?

When people on this site give a list of what to take to the hospital/ what to have on hand, I often see buy BIG underwear, Do they mean bigger what we already use? And also is this for everyone or just those w/ binders?

We greatly appreciate your interest in helping us build our Q&A database. To discourage vandals from posting garbage, however, we require people to register before posting.