The testes hang outside the body for a reason: They need to keep cool to function properly. Intentionally warming them with an ultrasound machine could kill off sperm cells permanently.
Contraception has had a rough couple of months. There was the great condom debacle in South Africa in January, when millions of government-supplied condoms leaked "like sieves." There was the oral contraceptive recall in the United States, in which one million packs of birth control pills were called into question after inert pills were thought to have taken the place of active ones. And then there was the Aspirin method that gained so much awareness last month.
Birth control is a real concern, not only because of the number of unwanted pregnancies in both developed and developing nations, but because it hasn't evolved much in the last few decades. For men, the evolution has been even more stalled; they have few options, aside from condoms, which can be unreliable, and vasectomy, which is not always reversible.
There's another technique, though, with a funny history but some serious possibility. In the 1970s, researcher Mostafa S. Fahim realized that ultrasound might be a possibility for male contraception, by "zapping" the testes past the point of functionality. The testes hang outside of the body for a reason: They need to be kept cooler than the internal body temperature to work properly. Too-tight underwear or excessive laptop use can cause a decrease in sperm production, enough to affect the odds of conception. In this vein, intentionally warming the sensitive testes with ultrasound might render them more clinically defunct.
"The monkeys didn't seem to mind the treatment a bit, but we were having a rough time of it. Thirty minutes of treatment three times a week is a lot of monkey testicular massage."
Fahim had shown that ultrasound applied to the testicles could significantly diminish sperm production in a number of species, including rats, dogs, and monkeys. Its benefits were that it was effective and, apparently, reversible. A few humans (scheduled to undergo testes removal for prostate cancer anyway) even underwent the procedure, and reported only a "gentle feeling of warmth" during application. But because follow-up studies couldn't replicate the findings, interest in the technique waned, and it was largely abandoned by the medical community.
But a recent study in rats may bring renewed hope for the procedure -- and for men willing to undergo it. Commissioned by the Male Contraception Information Project, researchers at the University of North Carolina put to the test the type of ultrasound machine commonly used in medical practices to restore damaged joints. The trick here was that the team, led by James Tsuruta, used the ultrasound to generate damage to healthy testicles.