The effect of a 6FG urethral catheter on urinary flow in benign prostatic hypertrophy.

Free voiding and micturition alongside a fine indwelling urethral catheter of similar voided volumes of urine were recorded for 43 men over 50 years of age. All had benign prostatic hypertrophy. Ten men had no bladder outlet obstruction, seven had clinically questionable obstruction, nine had slight obstruction and 17 had moderate or severe bladder outlet obstruction. I found no statistically significant lowering of peak flow rate when voiding was carried out alongside an indwelling 6FG catheter in subjects with no obstruction and with various degrees of bladder outlet obstruction due to benign prostatic hypertrophy. My findings demonstrate that the lower urinary tract is not a simple hydrodynamic system but a biologically functioning organ. The bladder outflow tract possesses considerable elasticity and accommodation. The present findings justify the use of the fine perurethral catheter technic for urodynamic studies, particularly in subjects with clinically questionable bladder outlet obstruction due to benign prostatic hypertrophy.