Urethral Segment Research Articles

Sonourethrography in the Evaluation of Urethral Stricture Disease

Ultrasonography of the anterior urethra offers a dynamic three-dimensional study that can easily be repeated. It holds the promise of defining accurately, not only the exact length and severity of the strictured urethral segment, but also the extent of urethral fibrosis and the anatomy of the periurethral structures. A significant reduction in the incidence of recurrent stricture may be obtained by selecting patients for treatment on the basis of the findings of sonourethrography. Moreover, the potential exists for the use of this imaging method during internal urethrotomy to ensure a more accurate and aggressive incision of the stricture.

Endoscopic Urethroplasty with Balloon Dilatation for Traumatic Disruption of the Prostatomembranous Urethra

A new technique is described for endoscopic treatment of a membranous urethral stricture after trauma. Urethral continuity was reestablished with a guidewire puncture and balloon dilatation of the obliterated urethral segment using simultaneous proximal- and distal-segment endoscopy with fluoroscopic alignment. This technique provides an easy and simple urethroplasty and may be a valuable alternative in bridging obliterated urethral segments after trauma.

Immunocytochemical Localization of Estrogen Receptors in the Normal Male and Female Canine Urinary Tract and Prostate*

We have used the monoclonal estrogen receptor (ER) antibody H222Sp gamma to localize ER by immunocytochemistry in frozen sections of the normal canine urinary tract of both sexes and of the normal prostate of the male. Striking regional heterogeneity of ER location was observed. In the urinary tract, specific ER staining was confined to nuclei of the transitional epithelium (mucosa) and subjacent stroma (submucosa) of the prostatic urethra in the male dog and of the proximal urethra in the female dog. In both sexes there was a gradient of ER staining intensity along these urethral segments. In the male, ER staining intensity was highest in the region of the verumontanum. The pattern and intensity of staining were similar in the male prostatic urethra and female proximal urethra, indicating a similar concentration of ER in these tissues, which have the same embryological origin. No specific staining was found in the kidney, ureter, bladder, or distal urethra of either sex. In the normal prostate, specific immunocytochemical ER staining was confined to nuclei of the prostatic stroma and prostatic ductal epithelium. Specific staining intensity appeared to be higher in the periurethral region of the prostate than in the periphery. No specific staining was found in the acinar epithelium of the prostate. Based on overall staining intensity there appeared to be a higher concentration of ER in the urethra than in the prostate. Scatchard analysis of [3H]estradiol binding confirmed a similar ER content in the urethra of male and female dogs and a higher ER content in the prostatic urethra than in the prostate itself (P less than 0.001). The location of ER in the normal canine prostate and prostatic urethra is consistent with the location of histological changes induced by estrogen administration, indicating that these immunoreactive ER probably represent biologically functional receptors.

Urethral reconstruction following an unsuccessful one-stage hypospadias repair

At present, essentially all cases of hypospadias may be repaired in a single stage on an outpatient basis or with a single night's stay. Urethrocutaneous fistula, anastomotic stricture, and meatal stenosis are the most common complications. A urethral diverticulum may develop following a transverse preputial island flap if the caliber of the neourethra is too large or secondary to postoperative urinary extravasation. Many of these patients have multiple complications that must be recognized. If a long urethral segment is needed to reconstruct a previously unsuccessful hypospadias repair, a repeat island pedicle flap or free skin graft may be used. More recently, a free bladder mucosal graft has been demonstrated to be quite effective.

Experimental studies with total and static urethral pressures in canine urethra and their clinical significance

AbstractCanine experiments were conducted in order to determine potential sources of error in measurement of total and static urethral pressures during urodynamic studies. Transmural urethral cannulas were inserted at various urethral sites, downstream and upstream of an elastic constriction, and attempts were made to study 1) the effect of increasing rates of urethral perfusion, 2) the differences in static and total urethral pressures at a urethral site, and 3) the differences between the static pressures recorded through the transmural cannulas and the intraurethral catheter. More than 300 pressure measurements were made in 14 dogs (both male and female). The results suggested that 1) static pressure increases with increasing rates of infusion, 2) when constrictions are applied in the midurethra, the increase of pressure is greater in the proximal (upstream) than the distal (downstream) urethral segments, 3) the total urethral pressures were (4 to 10%) higher than the static pressures, and 4) although statistically not significant, the static pressures recorded through the urethral catheter were lower than those recorded through the extraluminal transmural cannula.

The Effect of 5α-Androstane-3α, 17β-Diol and 17β-Estradiol on the Adult and Immature Chacma Baboon Prostate

We have studied the Chacma baboon prostate in an attempt to develop a primate model of benign prostatic hyperplasia. Anatomically, the baboon prostate can be divided into caudal, cranial, and prostatic urethral segments. A peri-urethral group of glands has been identified in the prostatic urethra. Following treatment with either 5 alpha-androstane-3 alpha, 17 beta-diol or 17 beta-estradiol, or the hormones in combination, the mature baboon prostate showed very little response by gravimetric or morphometric analysis. In contrast, the stimulatory effect of 5 alpha-androstane-3 alpha, 17 beta-diol on the caudal lobe of the immature baboon prostate and the prostatic urethral segment (a structure that is largely fibromuscular) was potentiated by the addition of 17 beta-estradiol. The weight of the immature baboon cranial prostate was increased by 5 alpha-androstane-3 alpha, 17 beta-diol treatment, but 17 beta estradiol did not potentiate androgen-induced growth. By morphometric analysis it could be shown that both the epithelial and stromal component of the immature baboon caudal prostate responded to 5 alpha-androstane-3 alpha, 17 beta-diol (androstanediol) treatment and that the addition of 17 beta-estradiol had a slight, but significant, potentiating effect on the androstanediol-induced increase of epithelial volume.

Pubectomy in Urological Surgery

Pubectomy has been useful, particularly for the treatment of traumatic disruption of the deep urethra after a preliminary cystostomy. This procedure provides unparalleled exposure for mobilization of the apex of the prostate and distal urethral segment, and the accomplishment of an end-to-end anastomosis. Results have been good.Pubectomy has been helpful in selected cases of chronic osteitis pubis. Experience with the technique was helpful during radical pubectomy in 2 patients with chondrosarcoma of the pubis.

The effect of 5α‐androstane‐3α, 17β‐diol and 17β‐estradiol on the adult and immature chacma baboon prostate

We have studied the Chacma baboon prostate in an attempt to develop a primate model of benign prostatic hyperplasia. Anatomically, the baboon prostate can be divided into caudal, cranial, and prostatic urethral segments. A peri-urethral group of glands has been identified in the prostatic urethra. Following treatment with either 5 alpha-androstane-3 alpha, 17 beta-diol or 17 beta-estradiol, or the hormones in combination, the mature baboon prostate showed very little response by gravimetric or morphometric analysis. In contrast, the stimulatory effect of 5 alpha-androstane-3 alpha, 17 beta-diol on the caudal lobe of the immature baboon prostate and the prostatic urethral segment (a structure that is largely fibromuscular) was potentiated by the addition of 17 beta-estradiol. The weight of the immature baboon cranial prostate was increased by 5 alpha-androstane-3 alpha, 17 beta-diol treatment, but 17 beta estradiol did not potentiate androgen-induced growth. By morphometric analysis it could be shown that both the epithelial and stromal component of the immature baboon caudal prostate responded to 5 alpha-androstane-3 alpha, 17 beta-diol (androstanediol) treatment and that the addition of 17 beta-estradiol had a slight, but significant, potentiating effect on the androstanediol-induced increase of epithelial volume.

Urethral replacement with autologous venous graft: an experimental study in the dog.

This study investigated the experimental replacement of the urethra with autologous vein grafts. A free transplant of external jugular vein segments were used to replace a resected urethral segment in dogs. We suggest that replacement of the urethra with autologous fraft could be applicable in the reconstructive surgery of the urethra.

Neural pathways to lower urinary tract identified by retrograde axonal transport of horseradish peroxidase

A new technique for tracing nerve fibers supplying specific organs by retrograde axonal transport of the enzyme horseradish peroxidase (HRP) was used to determine the innervation of various segments of the lower urinary tract. HRP was injected at the level of the bladder neck, postprostatic urethral segment, pelvic nerve, pudendal nerve, and pelvic floor musculature to determine precise nerve supply to each site, as well as possible overlap. The technique determines the exact spinal level of innervation, as well as the number of nuclei directly related to the motor neuron axons supplying innervation to each particular site. Representation of these nuclei at various levels of the spinal cord was shown in various serial sections obtained after the injection of HRP. This technique is accurate and precise; it is valuable in establishing exact neural anatomic connections between the central nervous system and target organs.

Micturitional static urethral pressure profilometry in women

AbstractMicturitional static urethral pressure profilometry is an accurate method to identify the location and degree of bladder outlet and urethral obstruction in men. Described herein are the results of micturitional static urethral pressure profilometry in 17 women: 13 were nonobstructed, 3 were obstructed, and 1 voided by abdominal straining. The location of the static pressure drop was in the terminal urethral segment in all patients and was clearly distal to the location of the maximum urethral pressure determined on urethral closure pressure profilometry. It is concluded that the terminal urethral segment controls urinary flow, determines the voiding pressure, and that micturitional static urethral pressure profilometry can accurately identify the location of physiologic obstructions in the female urethra.

Urodynamic Localization of Isolated Bladder Neck Obstruction in Men Studies with Micturitional Vesicourethral Static Pressure Profile

Micturitional vesicourethral static pressure profile, a method of recording the static (lateral) component of voiding pressure in the successive urethral segments contiguous with the bladder, has allowed us to establish directly the site and degree of bladder outlet obstruction in 16 men. The diagnosis of isolated bladder neck obstruction was confirmed with greater confidence by using this technique with a 10F trilumen catheter in conjunction with uroflowmetry and radiologic studies. Repeat studies with a 5F single lumen catheter have suggested that the obstructions recognized with the 10F catheter are not entirely artifactual. Our experience with this technique in several men with non-neurogenic bladder neck obstruction indicates the importance of including this study in the urodynamic armamentarium.

The zonal anatomy of the prostate.

Earlier morphologic studies of the prostate, though often extensive, have never systematically delineated its completed structure. Recent comprehensive analysis of 500 prostates has more precisely defined its anatomic composition, identifying previously undetected features and unsuspected complexities. Using a three-dimensional model, these structures and relationships are demonstrated. Four basic anatomic regions are described. The relationship of each to the urethra provides a central anatomic reference point. 1. The peripheral zone constitutes over 70% of the glandular prostate. It forms a disc of tissue whose ducts radiate laterally from the urethra lateral and distal to the verumontanum. Almost all carcinomas arise here. 2. The central zone constitutes 25% of the glandular prostate. Its ducts arise close to the ejaculatory duct orifices and follow these ducts proximally, branching laterally near the prostate base. Its lateral border fuses with the proximal peripheral zone border, completing in continuity with the peripheral zone, a full disc of secretory tissue oriented in a coronal plane. Marked histologic differences between central and peripheral zones suggest important biologic differences. 3. Preprostatic region. The urethral segment proximal to the verumontanum is kinked anteriorly at a 35-degree angle to the distal segment. No major ducts arise in the proximal segment, but the lateral rows of peripheral zone orifices continue. Duct development is aborted here, producing only a small transition zone and several tinier periurethral ducts. The development of these small ducts is possibly determined and limited by their intimate relationship to a periurethral smooth muscle sphincter that exists only proximal to the verumontanum. These small ducts in a restricted area are the exclusive site of nodular hyperplasia (BPH) origin. 4. The anterior fibromuscular stroma forms the entire anterior surface of the prostate as a thick, nonglandular apron, shielding from view the anterior surface of the three glandular regions. Its inseparable fusion to the glandular prostate has probably delayed recognition of the anatomic features described here.

A Urethral Lengthening Procedure for Epispadias and Exstrophy

A procedure to lengthen the urethra is described, which involves the tubularization of the top layer of the foreskin, maintains a good vascular supply and requires only 1 anastomosis. The short natural urethra, with whatever functional capability it may have, also is tubularized and dropped back to form the proximal urethral segment. This technique has worked well and gives a satisfactory cosmetic result.

Light and electron microscopy study on urethral regeneration.

In a series of experiments on dogs, it was feasible to replace a segment of urethra using wide-mesh Dacron. Light and electron microscopy study on the regenerated urethra showed no evidence of muscle, cavernous tissue and nerve regeneration. Although an excess of fibrous tissue surrounded the regenerated urethra, there was no change in the calibre of the new urethra after 7 months' observation.

The mechanism of urinary continence after prostatectomy.

An anatomical and neuropharmacological study of the urethra was performed in 19 patients after prostatetectomy to investigate the mechanism of continence. Anatomically, the urethral segment responsible for the postprostatectomy continence was located distal to the open prostatic fossa in the external sphincter which is comprised of intrinsic striated muscle and is called arbitrarily rhabdosphincter by the author. This unique striated muscle in the rhabdosphinecter appears to be primarily under the alpha-adrenergic influence in view of the change in the urethral pressure profile observed following alpha-adrenergic drugs.

Urodynamic measurements in enuretics

Distal urethral stenosis in girls as well as meatal and bulbar narrowed urethral segments in boys are still subjects of discussion about their pathologic value in the literature. The urodynamic findings in enuretic children by urethral pressure profile and cystometry frequently point to a outflow resistance. Calibration with bougies à boule, urethroscopy and permictional cysturethrography disclose such urethral narrowing. The survey of our own 107 enuritic children shows that urethrotomy has given good results relative to urodynamic data. The effect of methantheline medications consists in suppressing the hyperactivity of the detrusor.

REGIONAL VARIATION IN THE RESPONSE OF THE RAT VAS DEFERENS TO FIELD STIMULATION, TO NORADRENALINE AND TO TYRAMINE

SUMMARY 1. Experiments were performed with preparations obtained by medial transection of the rat vas deferens providing urethral and testicular segments, to determine whether the smooth muscle of this organ responds uniformly along its length to field excitation of sympathetic nerve terminals and to sympathomimetic amines. 2. Both preparations responded to pulses applied at 0.1 Hz with twitches which were blocked by guanethidine (1–10 μM) indicating that sympathetic nerve terminals were being stimulated. Xylazine (0.01–1 μM) also blocked the twitches. 3. In response to stimulation at 0.1 Hz the twitches of the urethral segment were larger but briefer than those of the testicular segment. However, the increase in tension with increase in stimulation frequency over the range 0.01–10 Hz was greater in the testicular than in the urethral segment. After a train of pulses at 1 Hz or above, the first few twitches of the testicular segment evoked by pulses applied at 0.1 Hz were facilitated, whereas twitches of the urethral segment were inhibited. 4. Noradrenaline (1–100 μM) and tyramine (1–100 μM) regularly enhanced twitches in response to stimulation at 0.1 Hz in the testicular segment but often reduced those in the urethral segment. Contractions in response to these amines occurred more regularly and were stronger in the testicular than in the urethral segment. The α-adrenoreceptor antagonists phenoxybenzamine (0.01 μM), phentolamine (10 μM) and thymoxamine (10 μM) blocked contractions and blocked or reversed the twitch enhancement produced by noradrenaline and tyramine. These observations indicate that the density of excitatory α-adrenoreceptors is greater at the testicular end of the tissue. 6. Twitch inhibition evoked by noradrenaline or by tyramine in urethral segments was resistant to blockade by phenoxybenzamine (0.01 μM), phentolamine 10 μM), thymoxamine (10μM) and propranolol (10 μM). 7. A histological comparison of the two ends of the vas deferens indicated that at the urethral end there was more circularly arranged muscle and that this interrupted bundles of longitudinally arranged muscle. The testicular end was thinner but had the higher proportion of longitudinally arranged fibres. 8. The differences between the two ends of the vas deferens in the arrangement of muscle layers and in the response to sympathetic nerve stimulation and to drugs may be of physiological significance in relation to the transport of sperm from the epididymis to the urethra.

Conduit and regional compliance of female canine urethra: Observations during voiding and passive urethral infusion

Studies with induced voiding and passive urethral infusion were conducted in female dogs to investigate the effects of compliance restriction and constriction on the proximal, middle, and distal urethral regions. The studies included an evaluation of various surgical procedures on the distal urethral segment and external meatus. Compliance restriction on the proximal and midurethral regions produced abnormal elevations in the voiding pressure and urethral infusion resistance. No such effects were noted when similar restriction to the expansibility was applied around the distal segment. Constrictions, on the other hand, resulted in severe degrees of obstruction. Procedures such as meatal dilation, generous meatotomy, and distal third urethrotomy paradoxically produced increases in infusion resistance (4 to 15 per cent) and slight diminution in the functional diameter of the proximal region. The physiologic and clinical implications of these results are presented.

Studies of enuresis: VII. Results of distal internal urethrotomy in girls with juvenile urinary incontinence

Sixty-two girls with daytime urgency urinary incontinence and/or nocturnal enuresis were studied by voiding urodynamics, voiding cystourethrograms, and urethral calibration prior to distal urethral segment caliber augmentation by internal urethrotomy, and postoperatively by voiding urodynamics and voiding cystourethrograms. Marked improvement or cure was seen in 51 per cent and at least moderate improvement in 71 per cent of the girls in whom urethral disfiguration was present on preliminary voiding cystourethrogram. No significant improvement was seen when urethral disfiguration had not been present. No correlation was noted between the degree of improvement and the preoperative distal urethral segment caliber. A new theory of the pathologic implications of urethral disfiguration is presented.