Time-controlled injectable occlusion of the vas deferens.

Abstract An injectable method of obtaining vas deferens occlusion is presented. The agent used is styrene maleic anhydride (SMA) with dimethyl sulphoxide as the solvent. The special feature of the approach is that after a period of time, spermatozoa passage is spontaneously reestablished. By varying the dose of SMA administered, the interval between injection and restoration of spermatozoa flow can be regulated from as short a period as about 3 months to more than five years.