PFO and diving: what a patent foramen ovale means for divers

After most dives there are small bubbles in the veins, which the lungs normally filter out. A PFO can let some venous blood bypass the lungs, so bubbles may reach the arteries. DAN figures suggest about 2.5 times the overall decompression sickness risk and about four times the neurological risk — though the absolute risk is still low.

No. The 2025 SPUMS/UKDMC statement advises against routine screening. Consider testing after cerebral, spinal, inner-ear, cardiovascular or skin DCS, or with migraine with aura, unexplained stroke, PFO or atrial septal defect in a first-degree relative, or other congenital heart disease. A diving physician should assess the indication; testing uses bubble-contrast echocardiography with provocation manoeuvres.

• Stop diving.
• Dive more conservatively — shorter dives well within no-stop limits, one dive a day, no heavy exertion for at least three hours afterwards.
• Consider PFO closure with specialists. Wait at least three months for repeat bubble-contrast echocardiography confirming adequate reduction or elimination of the shunt, and resume diving only once your treating specialist confirms that potent antiplatelet therapy is no longer needed; low-dose aspirin is acceptable under the statement. Closure does not eliminate all DCS risk.

Decide with a diving physician.