"The July Ward" by S. N. Dyer, which has a wiki page
I am trying to find a short story I read in which a new doctor makes a mistake that kills a patient. Doctor is distraught.
Soon after, John Doe #3 dies from complications and the surgeon
berates Tom. The situation overwhelms Tom causing him to feel guilty
for the patient’s death.
Later in the story a killer chases the doctor who goes through a door in an abandoned wing of the hospital. The wing is occupied by the ghosts of all the patients who died from mistakes by doctors in training. The ghosts protect the doctor from the killers.
Two gunmen soon arrive to assassinate the paraplegic patient and throw
the hospital into havoc. Dr. Watson escapes the ward and the two men
follow her back into the hospital's underground floors. They chase her
through rooms with preserved body parts and specimens until she turns
and enters the door labelled “The July Ward.”
In this ghostly ward, orderlies attend to neat and clean rows of
patients in beds. Dr. Watson stops to visit the first patient she
killed, apologizes once more, then compliments healthcare workers. The
two gunmen are apprehended by the ghost staff and Dr. Watson recalls
that “only two kinds of people may enter the July Ward— doctors, and
the dead. And only the doctors may leave.”
I believe I read it between 1996 and 2010. It may have been in a sci-fi anthology. I don’t read horror stories.
Published in Asimov's in 1991 but reprinted in SF anthologies in later years.