Purple urine bag syndrome.

Purple urine bag syndrome is a rare disorder where the plastic urinary catheter bag and tubing turn purple. The discolouration is due to the presence of indigo and indirubin pigments which are metabolites of tryptophan. It is associated with urinary tract infection. Bacteria that produce sulphatase and phosphatase are involved in the formation of these pigments. Purple urine bag syndrome is associated with higher morbidity and mortality, compared to urinary tract infection without this phenomenon. We present a case report of this rare phenomenon occurring in a 68-year-old woman.