New Modification of Koyanagi Technique Using Dartos Muscle Flap in Management of Proximal Hypospadias

Background: One stage urethroplasty through parameatal foreskin flap (OUPF) available for all types of hypospadias was first described by Tomohiko Koyanagi (1983). High complication rates were reported. Objective: To evaluate the outcome of Koyanagi technique modification using dartos muscle as a 2nd layer because it has a high vascularity, very thin, easily elevated, and leaves no complications. Patient and methods: This study was conducted in the Plastic Surgery Department at Menoufia University, during the period of April 2017 to April 2019. Thirty cases for proximal hypospadias were included during this study. After chordee release, urethra was constructed using Koyanagi technique and adding scrotal dartos muscle flap as a 2nd layer. Results: Patient's age ranged from 1 to 4 years with mean age of 2.83 ± 1.17. All of the 30 cases were with proximal hypospadias and had severe chordee. Early complications were detected as bleeding in 2 patients (6.6%). One patient (3.3%) reported for retention due to obstruction of the inserted catheter. Another case (3.3%) showed wound infection. The reported late complications were fistula in 6 patients (20%), meatal recession in 5 patients (16.6%), meatal stenosis in 3 patients (10%), and diverticulum in one patient (3.3%). Conclusion: The modified Koyanagi one stage repair of proximal hypospadias is an innovative technique and realize many criteria for expected effective operating results. The use of dartos muscle flap as a cover for the urethroplasty improves the results and minimize complications.