<chest medicine, radiology> A term used to describe partial or complete collapse of the lung, usually due to an obstruction of a bronchus (with mucus plug, infection or cancer). Atelectasis is commonly seen immediately in the post-operative period in those who have undergone general anaesthesia. Symptoms of atelectasis include low-grade fever, dry cough, chest pains and mild shortness of breath. Mild post-operative atelectasis is treated with deep breathing exercises and respiratory therapy. Atelectasis secondary to carcinoma will often be managed using bronchoscopy. (27 Sep 1997)