The Contribution of the Bladder Outlet to the Relation Between Pressure and Flow Rate During Micturition

  • Werner Schäfer


Since the measurement of bladder pressure and urine flow rate during micturition have become possible, numerous attempts have been made to describe, explain, and define the relationship between the two. Obviously a term such as “urethral resistance” should be suitable to define the relationship between the typical hydrodynamic parameters (pressure and flow rate); and analogies to more or less sophisticated fluid dynamics suggest themselves. The concepts of various “urethral resistance factors” have treated micturition as a simple hydrodynamic process and attempted to reduce the complex dynamics to a single number. However, the potential value of such a factor is poor and, based on physically inadequate assumptions, can be physiologically misleading. A more realistic concept, the “urethral resistance relation” (URR), shows the pressure/flow relationship during the whole process of voiding, but adequate interpretation is difficult.


Maximum Flow Rate Detrusor Contraction Detrusor Pressure Intravesical Pressure Peak Flow Rate 
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© Springer-Verlag New York Inc. 1983

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  • Werner Schäfer

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