Residual urine volume: correlate of urinary tract infection in patients with spinal cord injury.

During a program of intermittent catheterization and bladder retraining, patients were taught new voiding techniques to reduce residual urine volumes gradually. Results were taught new voiding techniques to reduce residual urine volumes gradually. Results of urine cultures done weekly were recorded. Data from 105 patients during 1,190 patient-weeks were analyzed to determine if residual urine volumes correlated with rates of urinary tract infection. Mean and median residual urine volumes were 192 ml and 176ml, respectively, for positive culture results and 159ml and 138ml, respectively, for negative results (p less than 0.01). A progressive increase in the rate of urinary tract infection was apparent between residual urine volumes of 100ml and 250ml. The rate decreased unexpectedly for residual volumes greater than 250ml; the explanation requires an additional antimicrobial mechanism.