Why “PUL Interventional Urodynamic Test” figure2 is a powerful
and accurate test
It is known that SUI occurs when the pressure in the urethra, or
preferably, the internal resistance to flow, is less than the motive
pressure (expulsive force) arising in the bladder. The pressure measured
in the urethra is actually a function of the urethral diameter (Pressure
=Force /Area). It is the area of “C” or “O”, figure1, which
determines whether urine is lost (or not). Area = πr2.
Simplistically, resistance to flow is inversely proportional to
πr4, the 4th power of the radius of
“O”. So though the pressure measured is only relative to the
2nd power of “O”, the same diameter “O”, figure1,
also actually reflects a 4th power change in
resistance to flow, which is a far more powerful parameter of change.