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A physical phenomenon known as elastic jump occurs downstream of an elastic constriction applied to a collapsible tube. This flow anomaly is analogous to the hydraulic jump that occurs in surface flows. Some investigators have predicted that an elastic jump could occur in the male urethra (during voiding) in the cavernous segment between constrictions at the membranous and meatal regions. To identify and understand this flow anomaly, and to obtain clinical correlations in human male subjects we have attempted several radiological and urodynamic studies in normal and abnormal subjects. The studies were retrograde urethrography, voiding cystourethrography, static pressure recordings during voiding and uroflowmetry. Retrograde urethrography was believed to delineate accurately the anatomy of the bulbous urethra. Voiding cystourethrography showed the geometry of the functional bulb. Our observations in 43 male subjects suggest that the site and degree of elastic jump depend on the severity of bladder neck or prostatic obstruction, magnitude of detrusor pressure (energy) during voiding, degree of distal constriction and position in which the subject voids. The animal studies (23 dogs) confirmed our clinical urodynamic impression.

The urodynamic study of the lower urinary tract is the only investigation that permits an evaluation of the vesico-sphincter function. On the ground of the personal experience of 3262 urodynamic study on 1221 children, the authors are reviewed the methods, indications, limits and pitfalls of urodynamics and synchronous video-flow-cystourethrography. Indications in the personal experience are: neuropathic bladder; non neuropathic vesico-urethral dysfunction; urinary incontinence; intravesical obstruction; recurrent cystitis; vesico-uretero-renal reflux and obstructive megaureter; nocturnal enuresis. Informations given by urodynamics in these pathologic conditions are very important for the diagnosis, prognosis and therapy. The urodynamic study is a very reliable and useful method, also in pediatric age, if correctly performed by expert investigators.

Multiple peak and average urinary flow rates were measured in 34 normal men. In addition, this population was compared to 114 patients with prostatic obstruction. No matter which flow rate measurement is used some overlap is present between the 2 populations. The sensitivity of the flow rate test was defined for the 90 or 95 per cent limit of each normal and abnormal population. The specificity of both tests also was statistically determined. The ability to separate abnormal from normal voiding is enhanced significantly if peak flow rate is the measurement made. The loss of specificity for average flow rate is owing to a greater percentage of both populations, normal or abnormal, within the overlap region between the 2.

Analysis of lower urinary tract function with an extension of standard renography with 123I-hippurate was carried out in 199 children. Maximum bladder capacity, voiding and residual bladder volumes, average and maximum urine flow rates and urine flow patterns were estimated. The index of urine transport (IUT), representing the relationship between urine flow rate and bladder volume, was introduced as a measure of outflow capability. Of 129 children without evidence of outflow obstruction, 90% had a normal urine flow pattern; in 96% the average IUT was 0.8 or higher and in 87% the maximum IUT was 1.2 or higher. A sawtooth-shaped pattern with both normal and abnormal IUT values was observed in 10% of these children. In 63% of the children with outflow tract obstruction there was a low, flat urine flow pattern together with decreased IUT values. A sawtooth-shaped pattern with varying IUT values was observed in 15%, whereas in 20% the urine flow pattern and IUT values were normal. This extension of standard radionuclide renography as a method of screening lower urinary tract function is recommended. It is at least as good as conventional direct urine flow rate recording, it has the advantage of being non-invasive and it is also part of an established urological investigation.

1. A new model of infravesical outflow obstruction was developed in male rats by the repeated s.c. administration of testosterone for 5-15 days (3 mg/kg die). The effects of this treatment which produced a 65% increase of prostate weight (10 days) on bladder voiding was evaluated in urethane anesthetized rats by the transvesical infusion of saline and compared to the cystometric alterations produced by application of a silk ligature at urethral level in female rats (4-8 weeks before) as described by Malmgren et al. (1987a, b). 2. Testosterone-pretreatment for 10 days produced little changes in bladder weight, bladder capacity or amplitude of micturition contraction but determined a marked increase in residual volume, indicating that infravesical outflow obstruction impaired significantly bladder voiding. Furthermore, detrusor instability was observed in the majority of testosterone-treated rats. 3. The participation of an active component to voiding impairment in testosterone-treated rats was suggested by the effect of intravenous prazosin which improved voiding efficiency. 4. In urethra-ligated female rats there was a marked increase in bladder weight which was paralleled by a dramatic alteration in micturition reflex that is marked increase in bladder capacity and residual volume. 5. It is concluded that these two models of infravesical outflow obstruction produce cystometric patterns simulating the urodynamic alterations observed in patients with benign prostatic hyperplasia and are potentially suitable for development of drugs in this field.

E-643, a newly developed alpha 1-adrenergic blocker with a postsynaptic action, was tried on 17 subjects, 10 patients with neurogenic bladder and 7 patients with lower urethral obstruction. The results of treatment were excellent in 5, good in 7, and poor in 5 of them, the rate of effectiveness therefore being 70.6%. The inhibitory effect of E-643 on the contractility of the detrusor was no stronger than that of other alpha-blockers. The rate of effectiveness for neurogenic bladders was as high as 80% whereas that for lower urethral obstruction was much lower: 57%. Concerning benign prostatic hyperplasia (B.P.H.) alone, this agent was markedly beneficial. In the case of B.P.H the urethra pressure in the prostatic urethra tends to drop and urination is facilitated even without a change in maximum urethral closure pressure, which reduces the amount of residual urine, this sequence of events taking place on condition that the contractility of the detrusor is adequate. According to urodynamic criteria, the underlying causes of the so-called bladder neck contracture can be classified into organic and functional obstruction, but it is mistaken to use this term for functional disturbance of the bladder neck. It seems worthwhile to determine the clinical effect of alpha-blockers on functional urethral obstruction. E-643 produced few if any appreciable signs or symptoms of side effects either subjectively or objectively.

Bladder outflow obstruction was produced in 18 young male pigs using either a silver ring or a silk ligature placed around the proximal urethra. Normal growth of the animals resulted in progressive obstruction. This was monitored by urodynamic studies in conscious animals, using either long-term indwelling bladder cannulae or by intermittent suprapubic catheterisation. At urodynamic assessment 3 to 5 months later, the obstructed pigs voided at an elevated pressure and with a diminished flow rate compared with control animals. Sixty-four per cent of the obstructed pigs developed detrusor instability, with spontaneous contractions exceeding 15 cm H2O during bladder filling; another 14% had decreased bladder compliance. In control animals the filling cystometrogram was stable, with little pressure rise during filling and no spontaneous contractions. This animal model provides the opportunity to study the physiological changes responsible for the development of detrusor instability in the obstructed bladder. It may also be useful for evaluating new treatment regimes for detrusor instability.

We investigated the intraurethral pressure changes at the external sphincter zone during voiding act and during an attempt to contract the anal sphincter on 26 neurologically intact subjects (normal group) and 12 cases after intrapelvic surgery (6 after amputatio recti and 6 after radical hysterectomy) (disturbed group). During voiding the pressure was decreased in 25 of 26 cases of the normal group, but was increased in 11 of 12 cases of the disturbed group. In contracting the anal sphincter, urethral pressure rose in all cases of both normal and disturbed groups. A significant positive correlation (p less than 0.01) was found in the urethral pressure changes between voiding and during the attempt to contract the anal sphincter in the disturbed group, but not in the normal group. It is supposed that the pressure decreased during voiding is an indication of not only normally functioning external urethral sphincter but also non-underactive detrusor, and that the pressure increase means either underactive detrusor or spastic external urethral sphincter due to detrusor-sphincter dyssynergia. To measure the urethral pressure changes at the external sphincter zone during voiding is thought to be useful for assessment of the urethral resistance at that zone.

Urodynamic investigation was performed in 21 boys with posterior urethral folds. An abnormal micturition pattern characterized either by varying degree of obstruction during the course of a micturition or by constant obstruction of "stricture type" was found in nine cases. The obstruction was generally of moderate degree. No micturition pattern specific for posterior urethral folds could be shown. Ten boys had enuresis. They did not differ from the other boys in regard to urodynamic variables. On the basis of clinical indications, 16 of the boys were operated on. Postoperative urodynamic follow-up indicated definite improvement or complete normalization in most of them, though urethral resistance was slightly increased postoperatively in three cases. Patients with posterior urethral folds probably should be treated by transurethral resection only if urodynamic investigation reveals an obstruction.

Low pressure/low flow voiding in young and middle-aged males in the absence of outflow tract obstruction has been reported as being associated with anxiety and a high incidence of dyspepsia. To assess objectively the psychological basis of this condition, an unselected group of 50 men aged 25 to 55 years was evaluated by psychiatric interview, questionnaires and urodynamic tests. In addition, patients involved in an earlier study were psychologically evaluated. Low pressure/low flow voiding was demonstrated in three (6%) of the new patients. This voiding pattern was related to a long preceding history, stress-dependent symptoms and difficulty in voiding in public urinals. When compared with a control population, the experimental group scored significantly higher on measures of psychoneurosis. It is recommended that surgery be avoided in these patients and that simple behavioural therapy may be most appropriate.

We treated 25 patients with posterior urethral valves by a perineal urethrotomy approach that required no sophisticated radiological or endoscopic equipment. The over-all results were considered good in 17 patients (68 per cent) who had restoration of normal micturition and renal function. Of the remaining patients 4 (16 per cent) had some residual stricture that responded to urethral dilation, 2 (8 per cent) had fairly normal micturition with occasional dribbling, 1 had persistent chronic renal insufficiency despite adequate relief of obstruction and 1 died of renal failure. The results of this approach are comparable to other methods described in the literature. The method is particularly appropriate in developing countries or in centers with limited urological facilities.

Urinary extravasation resulting in either urinary ascites or an isolated perirenal urinoma is relatively common in the fetus with severe obstructive uropathy. We examined the effect of fetal urinary extravasation on the developing kidney and abdominal wall in 12 fetuses taken from a series of 44 cases of fetal urinary tract obstruction. Based on this experience, we conclude that fetal urinary extravasation has predictable pathophysiologic consequences. Fetal urinary ascites appears to ameliorate obstruction-induced renal dysplasia by decompressing the high-pressure, obstructed fetal urinary system. Conversely, contained urinomas secondary to ureteropelvic junction obstruction provide inadequate decompression and are associated with renal dysplasia. Last, the severity of abdominal wall laxity (prune belly) relates directly to the timing and degree of fetal ascites.

A decrease in voiding pressures because of decreased outflow resistance has been demonstrated in 8 males, and conversely an increase in voiding pressures because of increased outflow resistance has been demonstrated in 7 females undergoing surgery. These changes occur in the early postoperative period.

The uroflowmetry is an essential part of the complex urodynamic examinations. One of its advantages is the non-invasive behaviour; the patient does not suffer any inconveniences. It is suitable for the evaluation of the success in surgical interventions due to obstructions in the lower urinary tracts, for control of results of the medicamentous therapy or after operative procedures, which have as their purpose the improvement of the function of the detrusor and for the general differentiation of diseases which are accompanied by dysuric symptoms. The technique renders possible the registration, the preservation of date and means an unlimited repeatable methody.

Because MM male mice suffer from a high incidence of urinary tract infection, an assessment was made as to whether the urethral plugs, which occur in male rodents, might be involved in its aetiology. When killed, males more commonly retained urine in their bladders than females but there was no significant difference between strains or method of killing. Males also voided urine more often during stressful handling followed by abdominal pressure, but also retained some urine more often than females. The study of sexually immature mice demonstrated no sex differences and no urine was retained in any bladder. It was concluded that the high frequency of urine retention in mature males is attributable to the presence of urethral plugs but these could not be implicated in the cause of MM urinary tract infection because of comparable findings in the controls. However, the possibility was considered that the plugs might facilitate infection of the kidneys once a bladder infection had become established.

In an attempt to simulate congenital hydronephrosis secondary to urethral obstruction, we evaluated the consequences of obstructing the urethra in fetal lambs by several techniques. When the urethra was ligated before 108 days gestation, the bladder decompressed through the urachus and the upper-urinary tract developed normally. Ligation of both the urethra and urachus produced gross bilateral hydronephrosis, hydroureter, and megacystis, as well as severe pulmonary hypoplasia, and was associated with a high perinatal mortality. Intermittent urethral obstruction produced with a balloon constrictor or by diverting urine externally and pressure-limited obstruction produced with a Pudenz valve both proved unsatisfactory for producing congenital hydronephrosis. Finally, ligation of the urachus and progressive gradual obstruction of the urethra with an ameroid constrictor produced hydronephrosis and pulmonary hypoplasia. This model simulates urethral obstruction in the human fetus and produces a clinical and pathologic picture similar to that seen in infants born with congenital hydronephrosis.

Urethral destruction is only occasionally the reason for prostatitis and Cowperitis and prostatitis is only demonstrated occasionally to complicate urethral stricture. It is a dependence of prostatitis and spastic urethral obstruction in the neuropathic bladder.