[Urethral resistance and bladder contractility]

Urinary difficulty results from an imbalance between deux forces: expulsive and retentive forces. Prostatic hypertrophy for instance only represents one of these forces. This presentation describes the numerous factors responsible for detrusor contractility which has been often ignored in the assessment of prostatic hypertrophy. The notion of urethral resistance is explained as a ratio of pressure flow which represents the only way to assess the obstructive factor.