Introduction. Violet or purple urine bag syndrome is a rare manifestation of chronic urinary tract infection in patients with permanent urinary drainage. Mainly, such unusual urine coloration develops in women. Risk factors also include constipation, chronic kidney disease, increased consumption of products containing tryptophan, which is explained by the pathogenesis of this phenomenon.

Сlinical case. This article presents a case of purple urine coloration in a 75-year-old patient with urothelial bladder cancer. Recurrence of cancer and, as a consequence, multiple transurethral resections with subsequent courses of intravesical BCG and chemotherapy led to the development of microcystis, obliteration of the left ureteral orifice and hydroureteronephrosis. A nephrostomy drainage was installed on the left, through which, for the last two years, constant purple coloration of urine has been noted. During natural urination, the usual straw-yellow color of urine remains. Catheter-associated infection is represented by bacteria of the genus Morganella morganii.

Conclusions. A change in the color of urine to a purple hue indicates the need for urinary tract sanitation, as well as an analysis of the functional state of the kidneys and intestines.