title: The purple bag syndrome.
abstract: This is an account of an unusual case of purple discoloration of plastic disposable urethral catheters and urine collecting bags. The likely causes are discussed with reference to the analogous situation of purple diapers in children. In this instance it appears that the phenomenon may have been due to the presence of indigo in the urine as a degradation product of tryptophan in the bowel lumen.
authors.forename: J A
authors.initials: JA
authors.lastname: McSherry