Urethral replacement with vascularized tunica vaginalis: Defining the optimal form of use

Purpose: Residual urethral defects after failed hypospadias surgery present difficulties in reconstruction. In these situations, repair using vascularized tissue flaps remains ideal, yet challenging. In order to offer more surgical alternatives in these cases, the use of vascularized tunica vaginalis flaps as urethral replacements has recently been established in an animal model. We undertook the following studies to further define the role of tunica vaginalis in urethral reconstruction. Materials and Methods: A vascularized flap of tunica vaginalis was used to replace an experimentally created 25-30 mm. gap in the anterior urethra of 26 rabbits, either as an onlay or tube flap. A control group consisting of 7 animals underwent only a segmental anterior urethral resection and primary re-anastomosis. Results: Satisfactory urethral healing occurred in all control animals that survived the procedure. All 8 animals which had tunica vaginalis tube flap reconstruction underwent contracture of the neourethra probably secondary to the presence of striated cremasteric muscle elements brought with the tunica during mobilization. All 16 animals available for long term study in the onlay flap group had excellent flap viability and 100% urethral patency rates. The mesothelial lining of the tunica was seen to be replaced by a stratified epithelial lining similar to the urothelial lining of the native urethra. Conclusion: The tunica vaginalis is a viable alternative to other tissues presently used for urethral replacement and can be used successfully as a vascularized onlay flap.