Purple urine bag syndrome is a rare clinical entity associated with chronic constipation in women, prolonged catheterization, and urinary tract infections. It is mostly caused by the reaction between synthetic compounds in the urinary bag and sulphatase or phosphatase produced by bacteria. Alkalinization of urine is also an important factor in purple urine bag syndrome. Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3894016/ Image via: https://www.amjmedsci.com/article/S0002-9629(16)30632-2/fulltext