From orange to red and all shades of yellow, most clinicians can list reasons for discolored urine. When urine appears purple, however, both patients and clinicians are taken off guard. Interestingly enough, Purple Urine Bag Syndrome (PUBS) is a very real however rare clinical phenomenon that cannot go unnoticed.
Purple urine bags are just that -the bags themselves appear to have a purple tint. The urine itself is not discolored. This happens when gram-negative bacteria that produce two specific enzymes (phosphatase and sulfatase) are present in the urine and react with PVC urinary catheters and bags. While urinary tract infections are common, especially among patients in long term care facilities, PUBS is not common since it is dependent on bacteria producing those specific enzymes.
Patients that present with PUBS are often geriatric females with a history of constipation and are catheterized. Patients most often have multiple comorbid conditions, however this could be coincidental due to the age and environment of care of the patient population from many case studies. Alkaline urine plays an important role as does dehydration. Constipation allows for an overgrowth of bacteria which introduces more potential pathogens to the body (including E. Coli). The final component of the purple color is the presence of tryptophan in the body, which when in the presence of sulfatase and phosphatase in an alkaline environment is converted to indigo (blue) and indirubin (red). When indigo and indirubin combine, they appear purple to the eye.
A purple urine bag is very apparent indication of a urinary tract infection that needs treated. If not treated quickly, septicemia can occur and outcomes can be fatal, especially considering the population this most often occurs in. By treating the underlying infection and therefore eliminating the presence of phosphatase and sulfatase in the urine, the urine bag for a catheterized patient will no longer turn purple in color when replaced.
Submitted by: Michelle Mikus, PharmD; Hospice Clinical Pharmacist at Delta Care Rx; Pharmacy Manager at ProCure Pharmaceutical Services
Lin CH. Huang HT. Chien CC, et al. Purple urine bag syndrome in nursing homes: ten elderly case reports and a literature review. Clin Interv Aging. 3:729-34. 2008
- Harun NS, Nainar SK, Chong VH. Purple urine bag syndrome: a rare and interesting phenomenon. South Med J. 100:1048-50. 2007