Scuba Diving Nosebleeds – What are “Mask Squeeze” and “Sinus Squeeze”?

Having a nosebleed while scuba diving is not an uncommon experience – especially with novice divers. The sight of blood in a dive mask may look terrifying, but divers should know that nosebleeds are mostly not a severe problem as long as they spontaneously stop. Blood from the nose is often mixed with mucus and tears, so the amount of blood loss is usually less than it seems (normally less than a tablespoon)!

Nosebleeds are experienced more often with novice divers than with experienced divers simply because of the way a new diver performs Valsalva maneuver as he/she descends. So – for those who do not know – what is Valsalva maneuver? The Valsalva maneuver is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one's mouth or pinching one's nose shut while pressing out as if blowing up a balloon. In diving, the Valsalva maneuver is often used on descent to equalize the pressure in the middle ear and sinuses to the ambient pressure.

Nice Youtube video explaining Valsava maneuver.

Barotrauma that is produced by inadequate performance of the Valsalva maneuver is commonly called mask squeeze. Briefly, mask squeeze results from not equalizing the pressure in the mast to match the water pressure, which creates a vacuum in the mask. This vacuum can directly transfer to the nasal passages. In a mucosa near the front of the nasal septum (1 cm away from nostrils) four nasal arteries connect together and form very fragile network of vessels. Affected by the vacuum, those very small and weak blood vessels can rupture and cause the nosebleed. Doing a slow descent while frequently performing the Valsalva maneuver can easily prevent the mask squeeze and nosebleeds. Mask squeeze is usually not accompanied by pain. Most of these nosebleeds will stop immediately as diver comes out of the water and do not need an emergency room visit or medical advice. 

The second (and usually more painful!) cause of scuba diving nosebleeds is due to what is known as a sinus squeeze, caused by a cold/allergy-associated blockage of the sinus openings. Sinus squeeze - also known as sinus barotrauma - occurs when a diver cannot equalize sinus pressure due to nasal congestion. In the case of blocked nose, there is almost always associated blockage of the sinus openings, and there is no gas flow between the nose and sinuses. The bony structure will not collapse under the pressure changes, but the lower pressure in the blocked sinus will draw blood into it. Blood vessels in sinuses will swell and leak. In more severe cases the squeeze results in a blood-filled sinus, which will drain during ascent when the air in the sinus expands. Sinus squeeze can be recognized as pressure or pain in the forehead or around the teeth, cheeks, or eyes. Sometimes – but not always – the nosebleed may occur. Pressure and pain regularly increase with depth.

The most common reasons for nasal congestion and sinus squeeze are colds and allergies, and they should be treated by proper medications. In a case of a sinus squeeze – until the congestion and sinus problems heal – divers should not be diving!

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Dr. Sasa Janjanin is double European Board-certified in ENT and Facial Plastic Surgery. Besides being experienced surgeon and proficient in curing problems related to thyroid gland; facial cosmetic procedures; nose, sinus and snoring complaints; and kids’ ENT problems, Dr. Janjanin’s particular expertise is in sport and diving-related ENT problems – acting many years as an ENT consultant for several professional and national sport teams and athletes, some of them Olympic medal and European championship winners.