This is a passage from an article on the origin of the idiom bite the bullet:
“Bite the bullet” was originally used quite literally, and referred only to the actual act of biting a bullet. Many times operations were performed in the field or in rough hospitals without the benefit of any kind of anesthetic. The soldier was given a bullet to bite down on. In order to avoid swallowing the bullet, he needed to maintain focus on the bullet between his teeth, helping him to think about something besides the pain he was enduring.
What does rough mean here when used to describe a hospital?