SAEM Clinical Images Series: The Color Purple

purple urine

A 64-year-old female with a history of quadriplegia and bladder rupture secondary to a motor vehicle accident two years ago, complicated by chronic indwelling suprapubic foley, presents from her skilled nursing facility with fever, oliguria, tachycardia, low blood pressure, and a change in the color of her urine.

Vitals: T 100.4°F; HR 126; BP 105/74; RR 24

General: Pleasant but mildly confused morbidly obese female smelling strongly of urine

Genitourinary: Poorly maintained indwelling suprapubic catheter with purulence noted around the ostomy and purple urine in her foley tubing and bag

Urinalysis (UA): 168 WBC, >182 RBC, Large leukocyte esterase, Positive nitrite

This is a case of Purple Urine Bag syndrome (PUBS), an uncommon subset of CAUTI that generally occurs in female patients with constipation and an indwelling foley. Although not fully understood, it is thought that the long stool transit time of constipation allows GI flora to break tryptophan down into indoles which travel to the liver via the portal system where they become indoxyl sulfate, which is excreted into the urine. Bacterial enzymes there catalyze this to indoxyl which oxidizes in alkaline urine to both indigo (blue) and indirubin (red), the combination of which, plus interaction with the plastic catheter tubing, causes the vivid purple discoloration. Risk factors include women, chronically catheterized, elderly, recurrent UTI, institutionalization, and chronic constipation.

Causative organisms are primarily gram-negative and include Proteus mirabilis, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa, Morganella morganii, and Enterococcus species.

Take-Home Points

  • PUBS is a rare subset of CAUTI primarily caused by gram-negative bacteria.
  • It is predominantly found in women, chronically catheterized, institutionalized, and constipated patients.
  • Treatment is appropriate antibiotics and improved foley hygiene, foley exchange as well as improved bowel regimen to increase stool transit time.

  • Meekins Pauline, Ramsay Amy, Ramsay Michael. Purple Urine Bag Syndrome. West J Emerg Med. 2012 Dec;13(6):499-500. 2. Scleszka Laura, Swan Tricia. October 9, 2020. Can Urine Color Guide Management? [online] EMRA. Available at: https://www.emra.org/emresident/article/purple-urine-bag-syndrome/ [Accessed 19 Dec. 2022]

Copyright

Images and cases from the Society of Academic Emergency Medicine (SAEM) Clinical Images Exhibit at the 2021 SAEM Annual Meeting | Copyrighted by SAEM 2021 – all rights reserved. View other cases from this Clinical Image Series on ALiEM.