Endoscopic sinus surgery - also called endoscopy or sinoscopy - is a procedure used to remove blockages in the sinuses (the spaces filled with air in some of the bones of the skull). These blockages cause sinusitis, a condition in which the sinuses swell and become clogged, causing pain and impaired breathing.

A thin, lighted instrument called an endoscope is inserted into the nose, and the doctor looks inside through an eyepiece. Much like a telescope with a wide-angle camera lens, the endoscope beams light into different parts of the nose and sinuses, allowing the doctor to see what is causing blockages. Surgical instruments can then be used along with the endoscope to remove the blockages and improve breathing.

This surgery does not involve cutting through the skin, as it is performed entirely through the nostrils. Therefore, most people can go home the same day.