OTHER URETHRAL ANOMALIES
Dra. Bernardita Troncoso1, Dr. Pedro-José López1-2
Paediatric Urology Department
Hospital Exequiel Gonzalez Cortes1 & Clínica Alemana 2
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- Anterior urethral valves, diverticula and megalourethra
These anomalies, which are confined to males, are eight times less prevalent than posterior urethral valves. In many aspects they constitute a continuum of urethral pathology while also being distinct entities in their own right. It is difficult to define the point at which the urethral dilatation proximal to anterior urethral valves constitutes a diverticulum, and similarly the point at which an extensive diverticulum becomes a megalourethra.
- Anterior urethral valves (AUV) are a much less common cause of infravesical obstruction, with as much potential morbidity as posterior urethral valves. As classically described, these take the form of either a fenestrated diaphragmatic membrane or a mucosal cusp arising from the ventral wall of the urethra. Because anterior urethral valves are occasionally found at the distal end of a diverticulum, it is unknown whether the anomaly developed primarily as a diverticulum with undermining of the distal urethra and secondary development of valvular obstruction or early valvular obstruction that resulted in proximal maldevelopment of the urethra and spongiosum.
- The embryologic origin of anterior urethral valves is somewhat controversial. It has been suggested that they may be the result of an aborted attempt of a urethral duplication, failure of alignment between the proximal and distal urethra resulting in a tissue remnant that may act as a valve, or congenital cystic dilation of periurethral glands resulting in a flaplike valve.
- These valves may be located anywhere in the anterior urethra. In 40% of cases the valve is sited at the bulbar urethra, whereas in 30% it is at the penoscrotal junction and in 30% in the penile urethra. They have rarely been reported in the fossa navicularis.
- AUV manifest with a wide spectrum of severity based on the degree of urethral dilation, presence of an associated diverticulum, and the grade of upper tract dilation.
- The presentation is with obstructive symptoms. These patients commonly have dribbling of urination, difficulty in voiding, incontinence, hesitancy or urinary retention, poor urinary stream, and recurrent urinary tract infections. Older children may also have enuresis, postvoid dribbling, or failure to thrive.
- Secondary changes in the upper urinary tracts are rare. However, in the neonatal period, the obstruction may result in megacystis, bladder rupture, severe hydroureteronephrosis, azotemia, or urinary ascites.
- Micturating cystourethrography is the diagnostic study of choice, as it demonstrates the obstruction. Interestingly, the urethra often appears narrow distal to the valves and dilated proximally. The valve itself may be visualized as a linear defect along the ventral wall but also may only be noted as an abrupt change in the caliber of the urethra. Vesicoureteral reflux has been noted in approximately one-third of patients, and upper tract dilation noted in one-half.
- Endoscopically, the valve appears as a filmy, ventrally located cusp or flap of tissue. It occasionally has been described as an iris-like membrane. One must examine the urethra carefully at the distal end of any urethral diverticulum because retrograde flow of irrigant may flatten the valve mechanism against the urethral wall. Suprapubic pressure with the bladder full and irrigation ports on the scope open may demonstrate the valve mechanism more readily. Furthermore, elevation of the valve with an endoscopic loop is invaluable in the identification of the lesion.
- Treatment is by endoscopic incision. Transurethral incision of the valve is effective for most patients, but one must be careful to aggressively incise to avoid any distal obstructing lip.
Endoscopic treatment does leave the patient with a urethral diverticulum in most cases. An occasional patient with a huge diverticulum and a defect in the spongiosum may benefit from open repair, which allows reconstruction of the valve, diverticulum, and investing tissues. In a rare patient with severe renal disease associated with obstruction, a temporary cutaneous vesicostomy may be used to allow drainage and improvement in renal function.
- Urethral diverticulum
- In the more common wide-mouthed form, usually located in the region of the penoscrotal junction, the distal lip may give rise to a form of valvular obstruction as the diverticulum undergoes progressive distension.
- Presentation is either with obstructive symptoms or with postmicturition dribbling.
- The rarer saccular lesions have a narrow neck and may occur anywhere along the length of the penile urethra, including in the fossa navicularis.
- Presentation is with urinary infection – rarely associated with stone formation within the diverticulum.
- Treatment is by endoscopic incision or resection of the obstructing lip or, rarely, by a perineal approach for the excision of a large diverticulum.
Is a rare congenital anomaly characterized by abnormal dilatation of the penile urethra in the absence of any evident obstruction. It may be associated with lack of corpus spongiosum or with complete absence of the corpora cavernosa. In such cases the penis amounts to little more than a floppy sac comprised of skin externally and urethral mucosa internally.
It shares some of the characteristics of a urethral diverticulum but includes more extensive and uniform involvement of the urethra.
The classification of fusiform and scaphoid types reflects the severity of the defect and the resultant effect on the corpus spongiosum and corpora cavernosum.
- The scaphoid form results from deficiency or absence of the ventral corpora spongiosum.
- A fusiform megalourethra also affects the dorsal sponge and corpora cavernosa.
- More recently, Adamson and Burge have described a third type with all corpora intact.
The cause of megalourethra remains somewhat controversial.
- Stephens postulated that a delay in cannulization of the distal epithelial core might lead to obstruction and proximal dilation.
- Others have suggested that embryologic arrest of the mesoderm investing the urethral folds influences the development of the corpora and erectile tissue.
Megalourethra is often associated not only with other urorectal anomalies such as imperforate anus, prune-belly syndrome, and urethral valves, but also with varying degrees of uropathy.
Diagnosis is often suspected on physical examination, particularly if the child is seen to void. The urethral meatus may be normally placed but pathologic.
- The rare and more severe fusiform type is often characterized by a soft, elongated phallus with palpably inadequate corpora.
- Ventral ballooning with voiding is typical of scaphoid megalourethra.
- Voiding cystourethrography and renal ultrasonography are performed to establish the diagnosis and evaluate the upper tracts.
Treatment centers on reconstruction of the urethra and corpora spongiosum using common principles of hypospadias repair. The scaphoid urethra can be opened longitudinally using the better dorsal and lateral tissue.
- The fusiform variety presents a much more difficult challenge depending on the amount of corporal tissue present. Some may be impossible to completely repair from a functional standpoint and benefit from corporal reconstruction with placement of penile prostheses as adults.
- Uropathy remains a significant problem.
- Abnormalities of cowper's glands and ducts
Cowper's glands are paired structures found along the posterolateral aspect of the proximal urethra, located on either side of the urethra. The main glands lie within the urogenital diaphragm, and accessory glands are located more distally along the bulbous urethra. Each gland is drained by a duct that courses medially and posteriorly through the corpus spongiosum to empty side-by-side in the bulbar urethra.
Cowper’s gland cysts (syringocoeles)
- Cysts, possibly developing due to obstruction of the orifices, may be seen as a filling defect along the floor of the bulbar urethra.
- Distension of the ducts, or of the glands themselves, may cause urethral compression or, if the anterior wall of the cyst ruptures into the urethra, may result in an obstructive membrane, in a diverticular structure in that area or retrograde filling of a prominent duct.
- Usually these abnormalities are asymptomatic, but they may cause terminal hematuria, bloody spotting at the meatus, postvoid dribbling, or obstructive symptoms.
- Most Cowper's duct anomalies are discovered as minor findings on voiding cystourethrography done for urinary tract infection.
- Surgical treatment is reserved for those patients who are symptomatic.
- Transurethral unroofing of a cyst typically is adequate, although one should take care not to leave a distal obstructing lip, which may act as a valve.
- Open resection by a perineal approach has been occasionally performed for a massively enlarged cyst producing obstruction.
- Urethral atresia and agenesis
Urethral atresia and agenesis must be included in the differential diagnosis of renal anomalies and bilateral hydronephrosis diagnosed in utero. Unfortunately, unless there is some other egress for the urine to escape the bladder, such as a patent urachus or an urorectal communication, these lesions are not compatible with renal development.
Management will depend on the specific anomaly and the amount of renal function salvaged by alternative urinary drainage.
- An association between urethral atresia and prune-belly syndrome in females has been recognized, but few reports discuss the outcome of treatment in these gravely ill infants. Most of these children will come to renal transplant due to severe renal damage that occurred in the neonatal period.
- In males, progressive catheter dilation has been used with reasonable success and would be similarly affective in males.
- Urethral duplications
Another rare set of urethral anomalies is duplication.
- Embryologic origin: Considering the many different anatomic variants, there is probably no common embryologic pathway to explain all findings of urethral duplication. Johnson suggested that faulty fusion of the genital ridge and urethral fold could result in two separate channels, and Lowsley proposed persistence of the urogenital plate during infolding of the genital ridge as an explanation.
- Anatomy: Urethral duplication can occur with complete duplication of the phallus or urinary bladder as a more severe abnormality. Most duplications occur in the sagittal plane with a single phallus.
- When one is found above the other in this setting, the ventral one is virtually always the dominant urethra.
- Woodhouse and Williams described sagittal duplication with the dominant, ventral urethra opening in an orthotopic position on the glans beneath a secondary epispadiac urethra.
- Sagittal duplication can also occur with the dominant urethra exiting in a hypospadiac position and the accessory urethra in the orthotopic position.
- Many of the nondominant dorsal urethras end blindly short of the bladder. If, however, they do reach the bladder, the child is often incontinent from the accessory channel.
- Classification: The wide variety of anatomic variations prohibits simple classification and easy division into specific categories. Simple, unique descriptions of each lesion as used by Effmann and colleagues based on the plane of duplication, the dominant urethra, and the position of the meatus are useful.
- Types of duplication:
These rare anomalies may be sagittal or collateral.
- Of these, the sagittal pattern is more common and takes the form of two channels running one above the other in the sagittal plane, whereas in the collateral form the duplicate urethras run side by side.
- The most common sagittal configuration comprises an orthotopic principal urethral channel and an epispadiac accessory urethra lying dorsal to it.
- In some cases both urethras leave the bladder separately and remain separate throughout their length, whereas in other cases the duplicate urethras unite distally to form a single channel.
- In the so-called ‘spindle’ variety the urethra separates into two components before reuniting again more distally, whereas in ‘Y’ duplications, an accessory urethra diverges from the main channel to emerge in the perianal region or the perineum.
- The dominant, ventral urethra typically has a normal path through the sphincter mechanisms and remains continent.
- In those cases associated with an epispadiac meatus, a widened symphysis pubis may be found, suggesting a relationship to the exstrophy–epispadias complex.
- In those patients with sagittal duplication and the dominant urethra in an abnormally ventral location, the anomaly can be complete or partial, in which case the urethra bifurcates distal to the bladder neck.
- The dominant, ventral meatus may be found anywhere along the penile shaft with the most severe position being that of a meatus located at the anterior anal verge.
- Despite that very abnormal location, the dominant urethra for urinary flow again is usually the ventral one, and the dorsal urethra is usually narrowed and inelastic.
- Management of the urethral duplication: Reconstruction is dependent upon individual anatomy but nearly always entails excision of the narrower accessory urethra.
- The anatomy can usually be well defined on voiding cystourethrography, which allows preoperative planning for correction.
- Endoscopy at the time of reconstruction may occasionally be necessary to completely understand the lesion.
- If the problem is noted because of minor splitting of the urinary stream during voiding, repair may not be necessary. Such consideration is typically only appropriate for those patients with both meatuses immediately adjacent to each other, and even those patients may benefit from a simple meatoplasty to combine both openings as one.
- Complexity of the repair increases as the two openings diverge, especially if the dominant ventral meatus is very proximal. In that situation, the ventral perineal urethra usually must be mobilized away from the rectum to a more orthotopic position and the remainder of the urethra reconstructed with a variety of urethroplasty techniques. A complete prepuce is useful when present.
- Obviously, patients should not undergo neonatal circumcision if the anomaly is noted.
- Mucosal grafts may be necessary in some patients having undergone prior circumcision or surgery. They also may be necessary for some patients in whom the prepucial skin is not adequate in length.
- With the aggressive dissection needed for reconstruction of the ventral urethra, exposure for excision of the accessory, dorsal urethra is usually good. That structure may also be anastomosed to the ventral urethra proximally. Passerine-Glazel and colleagues have described gradual serial dilation of the dorsal urethra to render it useful for voiding. We would prefer mobilization and reconstruction of the dominant urethra in most cases.
- Urethral Duplication in females:
- Complete duplication of the bladder and urethra is rare and particularly rare in females. In most cases, duplication of the bladder involves two bladder halves, each with a full-thickness muscular wall and each with its own associated urethra.
- An accessory urethra in the female is also rarely found communicating with the urachus.
- The cause of the condition is unknown, and the malformation varies so widely from case to case that it is unlikely that the same embryologic explanation can apply to all cases.
- Treatment is individualized but generally involves preservation of the ureterovesical attachments with anastomosis of the bladder or urethra as appropriate with excision of redundant tissue
- Urethral polyps
- Urethral polyps are another unusual anomaly of the male urethra. They may be congenital in nature but have also been reported in adults, suggesting that they can be acquired or that they may slowly grow until large enough to cause symptoms.
- These fibroendothelial lesions most commonly arise from the verumontanum and are typically covered with transitional epithelium over a fibromuscular core.
- Small polyps are usually discovered incidentally during the course of endoscopy for some unrelated purpose, whereas the larger lesions, with a polypoid head floating freely on an extended stalk, tend to obtrude through the bladder neck to give rise to acute, transient episodes of urinary retention.
- Other symptoms are straining to void, urgency and hematuria.
- Frank urethral bleeding may also occur.
- Diagnosis is by MCU or cystourethroscopy.
- Voiding cystourethrography often shows a filling defect in the urethra that may vary in location.
- Diagnostic confirmation is made by cystoscopy.
- Most polyps can be excised endoscopically (transurethral excision), although for large polyps an open transvesical approach may be required.
- Urethral strictures
Urethral strictures in children are the result of three etiologic possibilities: congenital, infectious, or traumatic (iatrogenic or noniatrogenic).
- The question as to whether congenital strictures truly exist has been previously debated.
- The distinction between a congenital and a type 3 valve can be quite difficult, with the first being just distal to the veru and the latter found in the membranous urethra.
- The true incidence of congenital stricture is not known. However, if one defines a stricture as being congenital when there is no known trauma or instrumentation, almost 14% of strictures found in children fit this classification.
- Infectious etiology is a rare cause of strictures in children due to the generation time for strictures to develop, often being decades.
- Inflammatory etiology should be considered different than infectious, and indwelling catheters play a role in development.
- A traumatic event is the single most important etiologic factor in the development of stricture in children.
- A straddle injury or iatrogenic trauma following endoscopy, traumatic urethral catheterization, and surgery accounts for most events leading to stricture. Previous series have shown posthypospadias surgery patients to represent the largest group of patients with iatrogenic stricture.
Whether congenital or acquired, such strictures are generally mild and respond well to endoscopic urethrotomy. Formal urethroplasty is rarely required.
Urethral Stricture in females:
- Urethral stricture or stenosis in the female was considered much more common in the past than currently.
- The “spinning top” urethra was initially believed to be an indication of distal urethral narrowing or stenosis, but it is probably more the result of bladder instability and discoordinate voiding than a true stenosis.
- In the past, when a voiding cystourethrogram (VCUG) demonstrated urethral narrowing distal to the bladder neck during voiding, it was assumed that bladder neck obstruction was the cause. It was believed that the urethra was wide because of poststenotic dilation or that habitual voluntary contraction of the striated sphincter resulted in dilation of the segment of the urethra between the urethral meatus and the bladder neck. With the following Y-V advancement of the posterior bladder neck, or urethral dilation, as many as 50% of patients were improved.
- The spinning top urethra probably results from a tendency for the female to hold the urine from time to time during development and normal toilet training.
- The most recent studies suggest that the spinning top urethra may indicate bladder instability in some girls, but bladder instability in “staccato” or intermittent voiding with dysfunction cannot be identified in all girls with an apparent dilation of the proximal urethra.
- The finding of a spinning top urethra on the VCUG should alert the examiner to functional disorders of the lower urinary tract. However, if no instability can be found with a thorough physical examination and appropriate testing, spinning top urethra should probably be considered a normal variant.
- From a practical standpoint, when evaluating girls with urinary tract infections or voiding disorders, you should look for the spinning top urethra. If that is combined with incomplete voiding or significant symptoms, the child should initiate biofeedback treatment.
- There is rare indication for urethral dilation in the female child today. It is not known whether urethral dilation is any more effective than training for dysfunctional voiding and it may in fact be harmful.
- Meatal stenosis
- Meatal stenosis is a common, usually acquired, abnormality of the male urethra.
- It is most often found in boys after newborn circumcision. Irritation of the meatus in the months or years following that procedure may eventually lead to narrowing of the meatus.
- The lesion is usually identified after toilet training when the urinary stream is easier to observe. The classic sign of meatal stenosis is a very narrow From a practical standpoint, when evaluating girls with urinary tract infections or voiding disorders, you should look for the spinning top urethra. If that is combined with incomplete voiding or significant symptoms, the child should initiate biofeedback treatment.
- There is rare indication for urethral dilation in the female child today. It is not known whether urethral dilation is any more effective than training for dysfunctional voiding and it may in fact be harmful.
- urinary stream that is upwardly deflected.
- In routine cases, not enough obstruction is created to cause renal or bladder effects or urinary tract infection. Some boys have a history of bloody spotting or intermittent dysuria who have responded well to meatotomy. Anecdotally, occasional boys have had resolution of enuresis with meatotomy as well.
- One should be careful not to overdiagnose meatal stenosis based on the visual appearance of the meatus. Meatal calibration or simple observation of voiding is typically diagnostic.
- Treatment consists of a meatotomy, which required an anesthetic procedure.
- Acquired meatal stenosis after surgical reconstruction of the urethra, particularly following hypospadias repair, can result in much more significant obstruction and sequelae.
The condition is uncommon but occurs in boys aged 6 years and upward, with presenting features that include dysuria, penile discomfort and urethral discharge or urethral bleeding – usually consisting of no more than spotting on the underclothes.
Attempts to culture a specific organism are unrewarding.
In the absence of other features, cystourethroscopy is not indicated, as it rarely makes a practical contribution to clinical management. However, when urethroscopy is performed, the findings are characterised by erythema of the anterior and bulbar urethra, with a granular appearance and strands of fibrinous exudate.
There is no specific treatment and the condition is self-limiting, although it sometimes runs a protracted course.
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