UK cardiologists have highlighted the risk of pulmonary oedema in open-water swimmers, after a woman in her 50s became breathless and started coughing up blood during a night-time swim. 

The woman, described as a competitive long-distance swimmer and triathlete, was diagnosed with swimming-induced pulmonary oedema (SIPE), they write in BMJ Case Reports. 

The condition, which is a subtype of immersion pulmonary oedema (IPE), is characterised by the accumulation of fluid in the lungs in the absence of water aspiration, which subsequently leads to acute dyspnoea, hypoxia and a productive cough. 

The case authors say it is a little-known hazard of open-water swimming, and the incidence rate of 1-2% is “likely under-reported”.