US doctors have reported the unusual case of a woman whose bladder naturally brews alcohol, labelling her condition ‘urinary auto-brewery syndrome’.

The 61-year-old US woman had been on a waiting list for a liver transplant, but urine tests for alcohol repeatedly came back positive, despite her assertions that she had not had a drink.

The Pittsburgh doctors eventually devised a laboratory experiment to demonstrate that yeast in her bladder could ferment sugar to produce ethanol, they report in the Annals of Internal Medicine.

The woman, who had cirrhosis and poorly controlled diabetes, had presented to the University of Pittsburgh Medical Centre Presbyterian Hospital, Pennsylvania, for placement on a waiting list for a liver transplant.