NAUI Open Water E-learning Practice Test

Sinus squeeze is a barotrauma of the facial sinuses that happens when you can’t equalize pressure in the sinus cavities during a dive. The openings into the sinuses can’t vent air properly if you have nasal congestion or don’t pinch and blow to clear them, so pressure builds and the delicate sinus lining tears. This bleeding can mix with mucus and drain into the mask, so you see blood and mucus on the surface. It’s a telltale sign of sinus involvement from pressure changes, not a trauma to the nose itself or an issue in the ears or lungs.

Distinguish this from ear barotrauma, which causes ear pain and possible hearing changes from the middle ear, and from nasal fracture, which would come with obvious facial trauma. Air embolism is an emergency with sudden severe symptoms like trouble breathing, confusion, or loss of consciousness, not just blood in the mask. To prevent sinus squeeze, equalize early and often, avoid diving with nasal congestion, and address any persistent sinus issues before diving.