The effect of a fine urethral pressure‐measuring catheter on urinary flow in females

Urodynamic evaluations of 221 female patients and 21 normal female subjects were performed to study the effects of a small ureteral catheter in the urethra on various voiding parameters. We found that the catheter induced a significant diminution of flow rate, interruption of flow, and stretching and flattening of the flow curves with respect to time. The most marked changes occurred in normal subjects and in patients with stress incontinence. The diminution of flow rate induced by the catheter was not strongly related to disease and varied so greatly within each statistical grouping that it was not possible to separate clearly the effects according to disease. Since the effects of the catheter were most marked on the normal population, catheter‐induced reduction of flow rate could not be used as an index of urinary outflow obstruction.