[Pastel in the urine bag].

Purple urine bag syndrome is a relatively unknown phenomenon in which the urine bag and the collector of chronically catheterized patients turn purple or blue. It affects predominantly women, and is mainly reported in elderly patients. The mechanism seems to be related to the appearance in the urine of two compounds that have been identified as indigo (blue) and indirubin (red) which bind to the urine bag and the collector.