The modified Koyanagi repair for severe proximal hypospadias

To report the method and results of a modified one-stage Koyanagi repair (urethroplasty with a parameatal-based and fully extended circumferential foreskin flap) to preserve the vascularity to the peripheral portion of the neourethra, in the repair of severe hypospadias.

Using a skin-incision line as in the original Koyanagi repair, a circumferential incision is made approximately 5 mm proximal to the corona and the urethral plate incised as for repair of chordee. A U-shaped skin incision is then made surrounding the meatus, extended to the dorsal prepuce for approximately 8 mm and parallel to the first incision. The tissue between the prepuce and dartos is dissected on the dorsal side to fix the prepuce as a neourethra to the dartos and to maintain blood supply. After mobilizing the loop-shaped skin flap through the button-hole of the pedicle, the internal and external sides of the loop are sutured to construct a neourethra. Twenty patients (aged 10 months to 9 years) with severe proximal hypospadias underwent the one-stage modified Koyanagi repair.

The repair was successful after the initial procedure in 14 patients, but urethrocutaneous fistulae developed in three and meatal stenosis in three. The overall success rate was thus 70%.

There were fewer complications than reported with the original Koyanagi repair, suggesting that the attempted vascular preservation of the neourethra was effective.