Urethral pressure changes during voiding.

Intraurethral pressure changes in the external sphincter zone during voiding were recorded using a specially constructed double lumen urethral catheter in 3 normal subjects. It was noted in all the 3 subjects that the urethral pressure in this zone dropped simultaneously with decrease of electromyographic activities of the external urethral sphincter when the subjects strained to void. It was ascertained for the catheter position to remain unchanged irrespective of voiding action during urethrometrography.