When the Urine Bag Turns Purple: A Benign Manifestation in a Chronically Catheterized Elderly Woman.

Purple urine bag syndrome (PUBS) is a visually alarming but generally benign phenomenon observed in chronically catheterized patients. It occurs due to bacterial metabolism of tryptophan derivatives into indigo and indirubin pigments, which stain the catheter tubing and urine collection bag. We report the case of an 87-year-old woman with chronic kidney disease (CKD) who developed sudden purple discoloration of her urine drainage bag during home care follow-up. Laboratory evaluation revealed alkaline urine, leukocyte esterase positivity, mild proteinuria, and elevated creatinine. No urine culture result was available at the time of assessment. Based on urinalysis findings, particularly alkaline pH and pyuria, a catheter-associated asymptomatic condition was suspected. Following catheter and bag replacement, hydration, and observation without empiric antibiotics, the discoloration resolved completely. This case highlights that although PUBS can be visually distressing, it often represents a benign, asymptomatic phenomenon in catheterized elderly patients. Awareness of PUBS can help avoid unnecessary antibiotic use in elderly catheterized patients.