Development of a catheterised bladder model to evaluate urinary drainage equipment

A catheterised bladder model was developed to examine the design features of urinary drainage bags. The drainage bag of 4 commonly used products was inoculated with either Escherichia coli or Proteus mirabilis. The speed of retrograde contamination towards the "bladder" was determined over 96 h. The effect of lifting the drainage bag above the level of the "bladder" was examined also. Within 4 days micro-organisms were detected in the backflow valves/drip chambers of all products, but contamination had not progressed as far as the catheter. Ps. mirabilis appeared to migrate more rapidly than Esch. coli. Lifting the drainage bag had no effect on the migration of either organism. The implications of these results for clinical practice are discussed.