Reversible Vasectomy Kills Sperm, Prevents Backups

Wired is reporting on an interesting reversible vasectomy technique being developed in India. Unlike traditional vasectomy, fluids are allowed to flow through the vas deferens, but an injected polymer made of styrene maleic anhydride and dimethyl sulfoxide interacts with passing sperm to effectively destroy the swimmers.
From Wired:

Rather than shutting down sperm production, with the potential side effects that entails, it acts more like a tollbooth on the sperm superhighway. As the negatively charged sperm pass by, they are essentially zapped by the positive charge of the SMA polymer. So a RISUG-injected man will still ejaculate millions of sperm, but most will be dead: tails snapped off, cell membranes ruptured.
As a contraceptive, RISUG faces a far more difficult road to approval and commercial acceptance than, say, a new antidepressant medication. While an antidepressant would be considered a success if it worked in 75 percent of patients, a contraceptive like RISUG will be compared to a conventional vasectomy, which works more than 99 percent of the time. Furthermore, it has to be free from the serious side effects that were common with early experimental hormone-based male contraceptives. And it cannot cause birth defects down the line—ever.

For the curious here’s a video of the procedure: