A modified bladder washout test to improve diagnostic results in chronic urinary tract infections.

Bladder washout (BWO) and antibody-coated bacteria (ACB) tests were performed on 25 patients with radiological and/or clinical evidence of chronic upper urinary tract infection (UTI) and 12 patients with asymptomatic bacteriuria. Using a traditional single-washout procedure, the BWO test gave equivocal results in many cases of chronic pyelonephritis; this seemed mainly due to the lack of complete bladder sterilization. A modified procedure, including double sterilization and irrigation, biochemical typing of isolated bacteria, and evaluation of temporal pattern of bacteriuria recurrence, was then introduced. Although preliminary results of the modified BWO test demonstrated a general improvement in the diagnosis of the infection site, it seemed rather difficult, at least in chronic UTI, to establish localizing criteria based on definite numeric changes in bacterial counts after washout.