Urethral pressure variations in women with and without neurourological symptoms

Simultaneous urethrocystometry was performed in 93 females without and 174 patients with neurourological symptoms. Both populations were divided into three age groups. The urethral pressure variation (ΔMUP) was calculated as the difference between the highest and the lowest maximum urethral pressure observed during 1 minute. In all age groups, both the highest and the lowest maximum urethral pressure recorded during bladder filling were significantly higher in the normal females than in the patients. There was, however, no significant difference in the degree of ΔMUP between normal females and patients in the different age groups. Typical urethral pressure variation was also observed during physiological bladder filling. Thus, urethral pressure variation in itself is a physiological phenomenon. With less difference between the lowest maximum urethral pressure and the bladder pressure, the possibility of leaking urine is increased. A urethral pressure decrease may therefore cause leakage in a patient but not in a normal female. More than 50% of the normal females had a urethral pressure variation of more than 20 cm H2O. The previous definitions of urethral pressure variations (unstable urethral pressure, urethral instability), which describe the condition as pathologic when the pressure varies more than 10, 15, or 20 cm H2O, can therefore no longer be considered useful.