In nasal endoscopy, the surgeon uses a device known as an endoscope (tube with lens or camera) to view the inside of the nasal passages and sinus passages. This procedure is often done if the patient seems to have or seems to be developing problems with these areas. To perform this procedure, the doctor generally passes the endoscope through each nasal cavity three times to look at different anatomical parts. The doctor might use either a flexible endoscope or a rigid endoscope. He or she might also remove tissue for examination or surgically remove any small abnormal growths in the nasal passages and sinus passages.