Functional endoscopic sinus surgery, or simply called endoscopy or endoscopy, is a surgical procedure performed on patients suffering from chronic forms of sinus infections. A functional endoscopic sinus surgery is the most common and basic of sinusitis surgeries. The endoscopic sinus surgery removes blockages or infection from the sinuses (air sacks between areas in the human skull). The blockages caused from an infection cause the sinuses to swell and become clogged with liquids which cause pain and severely impede breathing. The sinuses all possess a natural defense system to fight against foreign bacteria and allow air to flow freely from the sinuses to the nasal passage. When an infection occurs the defense system wanes, and germs are able to multiple and invade the sinus passages. When this happens, the sinuses become clogged, and exert a pressure on the facial bones causing an inflammation of not only the nasal passage, but the majority of the face as well.

The functional endoscopic sinus surgery is performed using a thin, fiber optic instrument called an endoscope. The endoscope is inserted through the nostril, and the majority of the surgery is performed through this passage. Archaic sinus surgeries were performed through an incision made in the cheekbone of an individual; this outdated procedure left the patient with irreparable scarring and a long recovery time. A functional endoscopic sinus surgery does not require any incisions for it is performed solely through the nostril. Once the endoscope has been inserted up the nostril, the physician will then look inside the patient's sinus using a wide-angle camera lens attached to the instrument. Much like a telescope this lens beams light into different areas of the nasal passage and sinus, effectively enabling the doctor to view the problems causing the blockage. Once the problem has been detected, a physician will employ varying instruments to correct the problem, remove the blockage, and improve the patient's breathing. Endoscopic sinus surgery, as mentioned before, does not require any cutting of the skin, thus enabling a patient to go home on the same day of the operation.

Originally developed in the 1950s, endoscopic sinus surgery has paralleled the field of medicine, by instituting various forms of innovative technology. Functional endoscopic sinus surgery aims to increase the amount of air flow through the sinuses by allowing mucus to drain properly out of the nasal passages. The surgery relieves nasal blockages and facial pains caused by a chronic sinus infection. Functional endoscopic sinus surgery is regarded as widely effective as more than 86% of patients have noticed a considerable reduction in the symptoms caused by chronic sinusitis. Although a sinus infection seems fairly routine the lingering effects of an untreated case can hamper an individual’s breathing pattern and overall way of life for years. Nearly 35 million Americans experience symptoms related to sinusitis annually; the problem with the infections prevalence is not only found in the susceptibility to spread the illness, but also in the general ignorance towards the lingering effects of the sickness. For many individuals the thought of an endoscopic sinus surgery seems daunting, however, with improvements made to technology and overall knowledge of the sinus system, the procedure is accomplished with minimal pain and effective results.