Definition. By Mayo Clinic Staff. Atelectasis (at-uh-LEK-tuh-sis) — a complete or partial collapse of a lung or lobe of a lung — develops when the tiny air sacs (alveoli) within the lung become deflated. It's a breathing (respiratory) complication after surgery.
It can be a finding in any setting. I am wonder why you are questioning the diagnosis, is there something else in the documentation that makes you think this is inaccurate?