Initiation of micturition: a study of combined urethrocystometry and urethrocystography in healthy and stress incontinent females.

Six continent and 4 incontinent females were examined by a combined technique of simultaneous urethrocystometry and rapid X-ray-film exposures. The study confirmed that pressure changes occurring in the urethra and bladder at initiation of voiding were not caused by artefacts of the measuring technique. It was found that the continent females initiated micturition mainly by a rapid decrease in urethral pressure followed by an increase in the bladder pressure. The stress incontinent females strained out the urine without initial urethral relaxation. Since the X-ray-technique did not add any new clinical information about micturition in females the pressure recording technique is recommended for routine investigation of micturition in females.