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HYPOSPADIAS

BACKGROUND

Depending on the localization of the external urethral orifice, hypospadias can be subdivided into distal (75%; glandular, coronary, subcoronary), intermediate (13%) and proximal (12%; penoscrotal, scrotal, perineal) forms. Differentiation between functionally necessary and aesthetically feasible operative procedures is important for therapeutic decision-making. As all surgical procedures carry the risk of complications, thorough pre-operative counselling of the parents is crucial.

DIAGNOSIS

Apart from the description of the local findings (position, shape and width of the orifice, size of the penis, information on the curvature of the penis on erection and inflammation), the diagnostic evaluation includes assessment of associated anomalies:

• Open processus vaginalis (in 9% of cases)

• Testis in a high position (in 5% of mild forms of hypospadias; in 31 % of posterior hypospadias)

• Anomalies of the upper urinary tract (3%)

Severe hypospadias with unilaterally or bilaterally impalpable testis and scrotal transposition require a complete genetic work up. In case of ambiguous genitalia, retrograde genitography should be performed soon after birth to exclude an adrenogenital syndrome (AGS).

A thorough physical examination, urinalysis and usually sonography are performed routinely in all forms of hypospadias. Excretory urogram or voiding cystourethrography (VCUG) are required only when the findings in the investigations mentioned above are inconclusive. Urine trickling and ballooning of the urethra requires exclusion of meatal stenosis by careful inspection.

TREATMENT

Surgical intervention is recommended for intermediate and more severe forms of hypospadias, and for distal forms with associated pathology (penile curvature, meatal stenosis and phimosis). In simple distal hypospadias, cosmetic correction should be performed only after a thorough discussion of the psychological aspects and clarification of the lack of a functional indication.

The therapeutic objective is to correct the penile curvature, to form a neo-urethra and to bring the neo-meatus to the tip of the glans penis, if possible. The use of magnifying spectacles and special suture materials, knowledge of a variety of plastic surgical techniques (use of rotational skin flaps, as well as free tissue transfer), the handling of dermatomes, wound care and post-operative treatment are essential for a satisfactory outcome.

Pre-operative treatment with the local application of testosterone propionate over a period of 4 weeks can be helpful. For distal forms of hypospadias a range of techniques are available (e.g. Mathieu, MAGPI, King, Duplay, Snodgrass, Onlay). Along with the 'skin' chorda, the connective tissue of the genuine chorda and the distal corpus spongiosum, running longitudinally under the glans on both sides of the urethral channel, are usually responsible for the curvature. If there is a residual curvature after chordectomy, and if the remaining skin channel of the open urethra is thin and of poor circulation, incision or excision of the urethral plate may be required. In corporeal dysproportion, orthoplasty (modification of Nesbit dorsal corporeal plication) must be added. Orthoplasty (Nesbit, modified Nesbit, Schroder-Essed) and closure may be considered in a two-stage procedure.

The Onlay technique with preservation of the urethral plate and avoidance of circumferential anastomosis is the method of choice, with low complication rates for moderate and severe hypospadias. Prerequisite is an intact and well-vascularized urethral plate, or a satisfactory result after the first session with a straight penis and a well-covered shaft. If the urethral plate is not completely preserved (after excision or division), a tube-onlay flap or an inlay-onlay flap are used. The two-stage procedure may be an option in severe hypospadias. If preputial or penile skin is not available, buccal mucosa, bladder mucosa and free skin grafts can be used.

Only fine absorbable suture materials should be used (6/0-7/0). For blood coagulation, bipolar instruments are required along with swabs soaked in 1:10,000 epinephrine solution. Glans preparation may be facilitated by infiltration with a 1:100,000 epinephrine solution. Tourniquets should not be used for longer than 20 minutes.

After preparation of the dorsal neurovascular bundle, modified Nesbit sutures (monofilic non-resorbable suture material 4/0-5/0, e.g. Goretex, Prolene) are placed with the knots folded in. Urine is drained via a transurethral or suprapubic catheter. In case of a suprapubic catheter, the neo-urethra should be stented. For urethral stenting and drainage, an 810 F catheter with multiple side holes is used ending in the bulbar urethra (not into the bladder). Circular dressings with slight compression, as well as an antibiotic administration have become established procedures.

Complications

Whereas meatal narrowing after splint removal can be corrected by careful stretching and the Dittel device, operative revision is needed in cases of a scarred meatus as slitting and stretching are ineffective in the long term. In urethral stricture, open surgery should be performed after one attempt at internal urethrotomy. With fistulae, revision should not be planned before a lapse of 6 months. Urethral stricture should be excluded intra-operatively as a cause of the fistula. To prevent the recurrent fistula formation, a dartos flap or a free tunica vaginalis patch may be used. Attention should be paid to adequate subsequent cover with mobilized Scarpa's fasciae.

Correction of a minor residual curvature, sometimes reported by the parents, should be discouraged, as it has no functional relevance. It can be easily corrected after puberty, if significant.