A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.

Commonly, atherosclerosis causes stenotic lesions in arteries. Stenoses can also be due to birth defects or disease processes including ischaemia, infection, neoplasm, or inflammation.

The resulting syndrome depends on the structure affected. Examples of syndromes that may be caused by various stenotic lesions include:

• strokes and transient ischaemic episodes
• Intermittent claudication
• angina
• obstructive jaundice
• bowel obstruction
• hydrocephalus