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Vol. 138, November Printed in U.S.A.
THE JOURNAL OF UROLOGY
Copyright© 1987 by The Williams & Wilkins Co.
ANTERIOR URETHRAL VALVES IN THE FOSSA NAVICULARIS IN CHILDREN HAL C. SCHERZ, GEORGE W. KAPLAN*
MICHAEL G. PACKER
From the Division of Urology, Children's Hospital, and University of California at San Diego School of Medicine, San Diego, California
Anterior urethral valves are an uncommon cause of lower urinary tract obstruction in children. They have been noted in the bulbous (40 per cent) and penile (30 per cent) urethra, and at the penoscrotal junction (30 per cent). None has been reported in the fossa navicularis. We encountered 3 cases in which anterior valves were located in the glanular urethra. This entity may be misdiagnosed as meatal stenosis and without a high index of suspicion it might be overlooked. The combination of distal obstruction and a normal urethral meatus should lead one to suspect this entity. Observation of the voided stream is extremely helpful in the diagnosis, since voiding urethrography often fails to include the penile tip and urethroscopy of the distal urethra often is unsatisfactory. Treatment can be performed either transurethrally or by excision through the meatus. ( J. Ural., 138: 1211-1213, 1987) Anterior urethral valves are an uncommon cause of infravesical obstruction in young boys. In 1960 Hope and associates were among the first to describe this lesion. 1 Since then many cases have been reported in the literature, either as an isolated finding or in association with a proximal diverticulum, 2- 6 both of which may represent extremes in a spectrum of events. 7 The valve itself will appear as a diaphanous to thick band of tissue on the ventral aspect of the urethra, assuming an iris-like, semilunar or cusp-like configuration. Of the anterior valves described 40 per cent have been in the bulbous urethra, 30 per cent at the penoscrotal junction and 30 per cent in the penile urethra but none has been reported in the fossa navicularis. 8 Most boys with anterior valves will have some difficulty voiding, although the degree will vary. Other presenting complaints include infection, ballooning of the urethra and irritative voiding symptoms. The diagnosis of anterior valves in the glanular urethra can be difficult, since the valves may be missed easily unless they are suspected. Ballooning of the urethra with voiding may distinguish valves in the fossa navicularis from more proximally situated valves. A voiding cystourethrogram is essential and characteristically will demonstrate a dilated urethra that abruptly changes caliber within the fossa navicularis. Meatal stenosis would be a tempting diagnosis based upon this finding but a high index of suspicion, careful physical examination to demonstrate a normal meatus and observation of the voided urinary stream will be helpful to make the correct diagnosis. Retrograde urethrography and urethroscopy usually will not be helpful. We report 3 cases of valves located in the fossa navicularis. CASE HISTORIES
Case J. R. M., a 3-year-old boy, was seen initially because of difficulties in toilet training, moderate urinary frequency and a split voided stream. A fistula was noted at the coronal sulcus ventrally. V aiding cystourethrography showed obstruction at the fossa navicularis as well as the described fistula (fig.1). In addition, the boy also had moderate penile chordee and an anterior urethral diverticulum proximal to the fistula. The penis was circumcised and the meatus was normal.
Accepted for publication April 21, 1987. Read at annual meeting of American Urological Association, New York, New York, May 18-22, 1986. *Requests for reprints: Division of Urology, University of California Medical Center, 225 Dickinson St., H-897, San Diego, California 92103.
The patient underwent a first stage Johansen urethroplasty and release of chordee. Meatotomy was necessary to correct meatal stenosis 2 months postoperatively and 10 months later he underwent the second stage repair. After an initial good result, the stream decreased in caliber and eventually a fistula formed at the base of the penis. After negative urethroscopy the fistula was closed primarily. Antegrade urethrography was performed owing to persistence of a poor urinary stream. A distal urethral narrowing suggestive of a stricture was noted but it was not confirmed by calibration. Repeat urethroscopy identified folds of tissue on the floor of the fossa navicularis. A crochet hook was used to engage, prolapse and excise the folds through the meatus. This was repeated after symptoms improved only partially and more tissue again was excised. Symptoms of poor urinary stream persisted and voiding cystourethrography again demonstrated distal urethral obstruction. The neourethra was excised and replaced with a free graft (Horton-Devine) urethroplasty. The patient voids with a normal stream 3 years postoperatively. Comment: Although the diverticulum was noted early in the course, its significance was not fully appreciated since the valve was re-fashioned inadvertently when the second stage Johansen urethroplasty was closed. In retrospect, an alternative procedure, such as a free graft urethroplasty to correct chordee and to replace the diseased urethra, might have been preferable from the outset and, thereby, would have avoided a protracted course. Case 2. S. S., a 5-year-old boy, was noted to have strangury when he was 1 year old, which was believed to have been caused by a stricture or an anterior urethral valve. The penis was circumcised, the meatus was located normally and of normal caliber, and there was no chordee. Physical examination was normal. Cystoscopy performed elsewhere when he was 3 years old revealed no abnormality. Some improvement had been noted until the patient was 5 years old when strangury recurred. Observation of the voided stream revealed marked ballooning of the penile urethra and a needle-like stream that was deflected dorsally. Voiding cystourethrography showed narrowing of the urethra at the fossa navicularis and dilatation proximal to the meatus (fig. 2). Urethroscopy revealed a valve on the floor of the fossa navicularis. The valve was prolapsed through the meatus by grasping it with forceps and excised with tenotomy scissors. At 6-month followup the patient voided with a good h d stream. Histological examination of the excised valve s owe squamous epithelium.
SCHERZ, KAPLAN AND PACKER
-r-~..,:::::::::;;;:,,·-...._ Anterior Urethral Valve
FIG. 1. Case 1. Voiding cystourethrogram (A) and sketch (B) demonstrate anterior urethral valve in fossa navicularis with proximal urethrocutaneous fistula.
Anterior Urethral/ Valve
FIG. 2. Case 2. Voiding cystourethrogram (A) and sketch (B) demonstrate anterior urethral valve in fossa navicularis
Case 3. J. K., an 11-year-old boy, had difficulty directing the urinary stream and he was referred with a diagnosis of meatal stenosis. Physical examination was significant in that he had 75-degree penile torsion, a circumcised penis with a normal meatus but a visible ventral flap of tissue arising within the fossa navicularis. With the patient under anesthesia the valve was grasped with forceps, prolapsed and sharply excised. The urinary stream was normal 3 months postoperatively. DISCUSSION
The embryological origin of anterior urethral valves is unclear. Williams and Retik reviewed the theories advanced during the years to explain the origin of anterior urethral valves in the penile urethra or more proximally. 9 Failure of the glanular and penile urethras to align themselves as they merge seems to be the most plausible explanation for valves located in the fossa navicularis. If the invaginating ectoderm fails to merge perfectly with the distally advancing urethral plate, resultant canalization might leave a flap that could obstruct the urinary stream. This theory is supported by the histological findings of squamous epithelium covering the valve in our case 2. It also is noteworthy that 2 patients had hypospadias variants (chordee in case 1 and penile torsion in case 3). This association may be important with respect to embryogenesis, since the invaginating glanular ectoderm usually does not meet the advancing urethral plate in patients with hypospadias. The differential diagnosis of urethral obstruction in the fossa navicularis must include in addition to anterior urethral valves meatal stenosis, lacuna magna (dorsal urethral diverticulum) and stricture (fig. 3). The presence of a normal meatus will exclude stenosis from the differential diagnosis. Lacuna magna has been well described 10 and it can cause irritative symptoms but it does not usually produce distal obstruction. The position on the dorsum of the glanular urethra distinguishes this from urethral valves whose leaflets arise ventrally. The septum separating the lacuna magna from the urethral lumen has been
Anterior Lacuna Urethral Valve Magna with Diverticulum Meatal Stenosis
FIG. 3. Schematic representation of various causes of urethral obstruction in children.
termed the valve of Guerin. Urethral strictures in the fossa navicularis usually occur as a result of iatrogenic trauma but rarely otherwise. Thus, a careful history will be helpful to eliminate stricture from the differential diagnosis. The radiographic appearance of meatal stenosis and anterior urethral valves in the fossa navicularis may be similar except for the distance between the point of obstruction and the soft tissue shadow of the glans penis. In the case of valves there is a soft tissue density between the point of obstruction and the tip of the glans on a voiding urethrogram, which does not appear in cases of meatal stenosis. Lacuna magna often is characterized by a small collection of contrast material dorsal to the roof of the urethra in the fossa navicularis.
ANTERIOR URETHRAL VALVES IN FOSSA NAVICULARIS IN CHILDREN
The treatment of anterior valves in the fossa navicularis often is simpler than when the valves are located more proximally. With observation of the voided stream during evaluation of the child or by expressing urine from the bladder with the patient under anesthesia, the valve may prolapse through the meatus. During anesthesia the prolapsed valve can be grasped with an instrument and then excised sharply. In some cases it may be necessary to place a crochet hook into the fossa navicularis and to engage the valve to prolapse it. Transurethral resection or ablation of the valve can be difficult because of the distal location. The incidence of postoperative complications should be low and none of our patients had urethral bleeding. Catheter drainage postoperatively is not required. The results were excellent in cases 2 and 3 in which the correct diagnosis was made initially and the valves were excised through the meatus. Admittedly, long-term followup is lacking. Failure to appreciate the nature of-the lesion in case 1 led to a frustrating succession of problems that might have been prevented had the lesion been identified at the outset.
and ballooning of the penile urethra is helpful in the diagnosis. With a high index of suspicion, this lesion may be treated easily, often by simple transmeatal excision. REFERENCES
1. Hope, J. W., Jameson, P. J. and Michie, A. J.: Diagnosis of anterior
2. 3. 4. 5. 6. 7.
Anterior urethral valves in the fossa navicularis should be considered whenever there is distal urethral obstruction. Obstruction demonstrated on voiding cystourethrography at the level of the fossa navicularis should not be taken as evidence of meatal stenosis when the meatus is normal. Observation of the voided stream for demonstration of a needle-like stream
8. 9. 10.
urethral valve by voiding urethrography: report of two cases. Radiology, 74: 798, 1960. Firlit, C. F. and King, L. R.: Anterior urethral valves in children. J. Urol., 108: 972, 1972. Firlit, R. S., Firlit, C. F. and King, L. R.: Obstructing anterior urethral valves in children. J. Urol., 119: 819, 1978. Small, M. P. and Schoenfeld, L.: Anterior urethral valves. Urology, 11: 262, 1978. Hartig, P.R., Koos, G. W., McKinley, C.R. and Meyer, J. J.: The value of the retrograde urethrogram in the diagnosis of anterior urethral valves. J. Urol., 118: 309, 1977. Blumberg, N. and Maletta, T. J.: Anterior urethral valve: complications and treatment. J. Urol., 108: 486, 1972. Burstein, J. D. and Firlit, C. F.: Anterior urethra. In: Clinical Pediatric Urology. Edited by P. P. Kelalis, L. R. King and A. B. Belman. Philadelphia: W. B. Saunders Co., vol. 1, chapt. 16, p. 558, 1985. Golimbu, M., Orea, M., Al-Askari, S., Morales, P. and Golimbu, C.: Anterior urethral valves. Urology, 12: 343, 1978. Williams, D. I. and Retik, A. B.: Congenital valves and diverticula of the anterior urethra. Brit. J. Urol., 41: 228, 1969. Sommer, J. T. and Stephens, F. D.: Dorsal urethral diverticulum of the fossa navicularis: symptoms, diagnosis and treatment. J. Urol., 124: 94, 1980.