[Catheter measurements of the urethral pressure].

The outflow of viscous incompressible fluid from catheter holes into a small gap between the catheter and surrounding elastic tube is considered. Initially, the catheter is inserted into the tube lumen in such a manner that a considerable tube wall prestress exists. An additional longitudinally non-uniform external load is applied to the outer tube surface. The procedure of measuring the urethral "pressure profile" is discussed. It is shown that there is no easy way for extracting the external load (muscle forces in reality) from the measured pressure.