[Infravesical obstruction].

Infravesical obstruction presents clinically in the form of dysuria. Urodynamic studies play an important role to distinguish between a disorder of detrusor contractility and a functional or organic obstruction. The value of uroflowmetry, static and voiding urethral pressure profiles, cystometry and electromyography is discussed. The instantaneous voiding profile appears to be the most useful test: it allows calculation of urethral resistance, which is the ratio between bladder voiding pressure and the square of flow. Bladder neck obstruction is present in more than 80% of cases with a value greater than 0.5. Obstacles are more easily identified clinically in women, but the same tests can be applied with a poorer reliability for urethral resistance.