The effect on the bladder pressure of sudden entry of fluid into the posterior urethra.

The posterior urethra was stimulated by the rapid injection of saline against the urethral wall. The effect was studied in 50 female patients attending a urodynamic clinic. The injection was made via a double lumen catheter, and bladder, urethral and rectal pressures were observed during and after the ingress of fluid. The results indicate that sudden entry of fluid into the posterior urethra does not initiate a detrusor contraction even in those patients in whom the injection of fluid is painful. The relevance of these results in relation to the unstable bladder and urodynamic tests is discussed.