URETHRAL REPLACEMENT WITH VASCULARIZED TUNICA VAGINALIS - DEFINING THE OPTIMAL FORM OF USE

Purpose: Residual urethral defects after failed hypospadias surgery pr esent difficulties in reconstruction. In these situations, repair usin g vascularized tissue flaps remains ideal, yet challenging. In order t o offer more surgical alternatives in these cases, the use of vascular ized 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 reconstructio n. Materials and Methods: A vascularized flap of tunica vaginalis was used to replace an experimentally created 25-30 mm. gap in the anterio r urethra of 26 rabbits, either as an onlay or tube flap. A control gr oup consisting of 7 animals underwent only a segmental anterior urethr al resection and primary re-anastomosis. Results: Satisfactory urethra l healing occurred in all control animals that survived the procedure. All 8 animals which had tunica vaginalis tube flap reconstruction und erwent contracture of the neourethra probably secondary to the presenc e of striated cremasteric muscle elements brought with the tunica duri ng mobilization. All 16 animals available for long term study in the o nlay flap group had excellent flap viability and 100% urethral patency rates. The mesothelial lining of the tunica was seen to be replaced b y a stratified epithelial lining similar to the urothelial lining of t he native urethra. Conclusion: The tunica vaginalis is a viable altern ative to other tissues presently used for urethral replacement and can be used successfully as a vascularized onlay flap.