MORPHOLOGICAL OBSERVATIONS OF VAS-DEFERENS OCCLUSION BY THE PERCUTANEOUS INJECTION OF MEDICAL POLYURETHANE

Histological observations of 20 occluded vas segments obstructed by th e standard procedure of medical polyurethane-vas occlusion in 10 volun teers requesting vasectomy and of 20 vas segments with plugs removed f rom 10 vas-occluded men requesting vas reversal were carried out in or der to elucidate the mechanism of vas occlusion by medical polyurethan e (MPU). Twenty vas deferens in vasectomy group were ruptured, only a small amount of MPU elastomer remained within the vas lumen, most havi ng leaked through to encircle the ruptured vas. Histomorphology of the removed vas segments from 10 vas-occluded men, who had undergone MPU- vas occlusion 4 years earlier, showed diffuse proliferation of connect ive tissue, fibrosis, or hyalinization of fibroplastic tissue and loca l infiltration of lymphocytes and macrophages. The vas lumen both prox imal and distal to the plugs was completely blocked. Sperm granuloma, foreign body granuloma, proliferation of nerve fibers and local infilt ration of lymphocytes were found in four vas-occluded men with painful nodules. These results suggest that the contraceptive mechanism of MP U-vas occlusion could be the result of secondary obstruction due to ti ssue proliferation by MPU irritation after the rupture of the vas defe rens.