Introduction
The Koyanagi technique has received a lot of attention for its logical flap design since its development[1; 2]. Many modifications of the Koyanagi technique have been introduced because of its high complication rate[3; 4; 5; 6]. But the complication rate didn’t drop much. We believe that the high complication rate is mainly due to the disruption of blood supply to the flap. Here, we development a modified Koyanagi technique that improves the blood supply of the flap for single stage repair of severe hypospadias, thereby greatly reducing the occurrence of complications. Similar to the Koyanagi technique, the urethral plate was recreated using foreskin, but then a sealed Y-shaped incision was made on the original and recreated urethral plate. Different from the Koyanagi technique where the foreskin is cut, it only be cut to the skin layer, we divide the foreskin into the epidermal layer and the subcutaneous tissue layer. The epidermis is cut off, but the subcutaneous tissue is separated and the vascular system is protected. In this way, the blood supply of the flap is intact, reducing operation failures caused by avascular necrosis of the flap.