Fiberoptic bronchoscope is a kind of medical equipment used to check and diagnose lung diseases. Observing the inside of the airway can help doctors diagnose pneumonia, lung cancer, emphysema and other diseases. If the patient has no sputum, it is not appropriate to use fiberoptic bronchoscopy to take sputum. This is because fiberoptic bronchoscopy is an invasive examination, which will cause damage to the respiratory tract. If the patient has no sputum, there is no need for such an invasive examination.