I dropped a first aid kid up stairs in the entrance of the corrider or rooms and it fell through the floor in between the back wall of the hospital and the wall you see before you walk up the stairwell.
Hopefully my screenshots will explain it better.

After noticing where my med kit went I tried to vault/jump through the wall to get it. I was able to see through the wall just by vaulting and walking towards the wall. And when I walked towards the wall, vaulted, and then immediately crouch, "x", and log off. When I logged back in I would seemingly be in the void between the two walls, but I couldn't interact with the first aid kit. And any movement would "knock" me out of that void back into the hospital stairwell.

I've done something similar to this with an M4 and was able to get it back. Hopefully my ramblings can help somehow. {F29961} {F29962} {F29963}