The evaluation of someone with atelectasis begins with a medical history and physical examination.

Physical findings in those with atelectasis may include:

• Increased respiratory rate
• Decreased lung sounds
• Wheezing

Tests are required to determine the underlying cause for the atelectasis.

Tests that may be used to evaluate atelectasis include:

• Complete blood count
• Kidney profile
• Serum electrolytes
• Pulse oximetry
• Chest x-ray
• Bronchoscopy:
• Can obtain a tissue sample during this procedure
• Sputum cytology:
• Testing the cell from lung mucus for cancer
• Telomerase:
• A blood test that may be abnormal if lung cancer is present
• CT scanning of the chest:
• A more sensitive method
• MRI scanning of the chest
• Pulmonary function tests