Hospital
There aren't many levels leftovers in the files at all for the hospital, but what's most interesting is the levels written in the PuzzlePieceSystems.
There is only a single unused level in the files. Called LVL_3_080_Respirator. Apparently it's an older version of the room with the living patient. I honestly think this one is way prettier than the one we got.
The hospital, at the start of the chapter, was supposed to have a pharmacy.
There was supposed to be a puzzle involving a fire hose
Six was supposed to be trapped with the doctor
Originally we would go through a surgical area leading to the doctor's private launge/office
Thin man would appear and take six
As shown in the concept art, there was supposed to be a lot of experimentation going on involving "Cordyceps". These parasites were very involved in the hospital chapter and also in the school one (except there is only shown in concept art). Despite being seemingly cut, there's still an in-game photo asset that is used showing the experimentation hall with kids in beds.
Lastly, there was a basement with a chamber filled with moths.
Extra: this one i always found interesting. Apparently the teacher would've hadquarters in the hospital? i think it might have been a mistake in organization on Tarsier's part, but who knows?