Investigations of micromotion characteristics of bladder wall strips and pressure wave phenomena in total bladders in vitro and in vivo indicate that m~cromotion phenomena occur in the bladder wall. Local contractions can occur without an increase in tension or pressure, because other pans are in antiphase. Local contractions stretch surrounding tissues, which can stimulate fast stretch receptors. Synchronisation of these micromotion phenomena appears to be possible. Hence, above threshold levels urge can theoretically occur, even in the absence of a pressure increase. This hypothesis could explain the weak relation between urge and pressure. The distinction between motor and sensory urge could be artifactual based on a misunderstanding of fundamental bladder wall processes.

The results of a retrospective study of 67 patients with scrotal varicocele on the left side are presented. By means of preoperative venography of the renal, internal spermatic and common iliac veins 3 types of varicocele could be distinguished in which the cause arises in the internal spermatic vein and/or the varicocele is caused by obstruction of the common iliac vein. Use of routine preoperative venography is essential to establish the etiology of the varicocele and its proper management.

The bladder wall is composed of passive (collagen, elaftin) and active (smooth muscle) elements. Some of the smooth muscle cells have properties of "pacemakers" in that they show spontaneous activity at rest. Moreover, when these cells are stretched, the resting membrane potentials decrease and the frequency of action potentials increase. It has been further demonstrated that both in vitro muscle strips and in vivo bladder preparations show spontaneous activity which may generate both tonic and phasic changes in bladder wall forces. The rate and duration of stretch both affect the force that the cell can generate. Thus, the filling pressureivolume curve obtained by systometry represents an interaction between the active and passive elements of the bladder wall. Since the cystornetric curve is time dependent, it is impossible to compare cystometrograms unless this time dependency is taken into account. With these principles in mind it is possible to standardize the terminology for characterizing detrusor activity during the collection phase as outlined in this report.

The passive behavior of the urinary bladder in the collection phase is described by a number of independent input–output relations characterizing the function of the bladder wall and the geometry of the bladder. Assembly of these relations yields a model characterized by twelve parameters. Two of these parameters can be determined from a static cystometrogram. Stepwise filling of the bladder gives a pressure-decrease curve which can be described by three exponential terms and a constant and yields nine of the desired parameters, or ten if two or more fillings are done on the same bladder.

Stepwise cystometry is a new method proposed to analyse the visco-elastic properties of the bladder. It is based on a mathematical analysis of the pressure decay after a stepwise filling. By assumption of a mechanical visco-elastic model of bladder tissue and a model of the geometry, the derived parameters are interpreted as elasticity and viscosity moduli. Static cystometry is involved in this new procedure. From analysis by stepwise cystometry it is concluded that static cystometry attained by following a slow-filling procedure is unacceptable in studying elastic behaviour.