Reversible inhibition of sperm under guidance (RISUG) is a procedure that could someday replace vasectomy as a long-term form of birth control. While RISUG and vasectomies have similar goals, the way they achieve those goals are quite different. Vasectomies involve cutting the vas deferens, and tying/stapling/cauterizing the open ends of the vas deferens. Even with the minimally invasive no-scalpel vasectomy, it is still a surgical procedure. RISUG is different- there is no cutting involved. Instead of severing the vas deferens, a polymer known as styrene maleic anhydride (SMA) is injected into the vas, which quickly hardens. This barrier does not block sperm; rather, it renders all the sperm that passes through it inactive, preventing conception. Reversing it simply requires another injection which dissolves the polymer, allowing the passage of motile sperm.
RISUG provides a solution for a couple of problems that still affect vasectomies. First, it prevents backpressure from sperm in the epididymis and granulomas, which, while rare, are still a potential inconvenience for some who have a regular vasectomy. While RISUG procedure is not permanent (~10 years), it is very affordable and can be replaced indefinitely. It’s impermanence is a feature for some, as it is very easy to reverse the procedure. In the past few years, vasectomy reversals have become very effective, but they’re still known to fail and are costly compared to the initial vasectomy. The recovery time is short, and couples may resume intercourse within a week.
Unfortunately, its development both here and abroad has been rocky. As of last year, advanced clinical trials on humans had very few volunteers- just 64 out of a targeted 500. In the US, the intellectual property rights are owned by the Parsemus Foundation, a non-profit, and is called “Vasalgel™”. Animal trials so far have been successful, but it still may be some time until human trials begin. Hopefully, this technology will one day revolutionize male birth control, but for now no-scalpel vasectomies are the best option for those seeking long-term male birth control.