A chest x-ray is usually requested to diagnose the cause of chronic cough. Other tests that may be necessary depending on the symptoms of the patient include breathing tests to check for lung function, blood tests, sputum studies, other x-rays (such as those of the sinuses), barium swallow and other gastrointestinal tests to check for GERD, a CT scan of the lungs, and bronchoscopy, wherein a tube with a camera is inserted into the bronchi and the lungs are directly studied for any pathology.