Despite the need for male contraception and the fact that vas-occlusive devices have been tested for decades, no product has been successfully introduced to the market. The characteristics of the occlusive material are critical and previous attempts to use solid or semi-solid material had side effects or unacceptable efficacy. For example, a urethane intra-vas device tested in 288 men in China proved to be only 94.3 % effective, not matching vasectomy’s 98.6 % effectiveness in the study [12].
