Men’s options for contraception have typically been limited to condoms or vasectomy, but research published January 30 in Reproductive Biology and Endocrinology touted the potential of another male contraceptive: therapeutic ultrasound.
Researchers at the department of pediatrics at the University of North Carolina School of Medicine in Chapel Hill, led by James Tsuruta, PhD, are the latest in a series of researchers dating back to the 1970s who are looking into the possibility that applying commercially available ultrasound to the testes can decrease sperm counts enough to be an effective contraceptive.
Therapeutic ultrasound is used by physical therapists to heat injured joints and increase circulation, but when that same technique is applied to the testes, it results in long-term contraception. Up to two and a half months of contraception has been achieved in rats with two 15-minute sessions of ultrasound across two days.
"Sperm production is very robust; this ensures the survival of a species. It's really difficult to find a way to turn off the production of sperm, but ultrasound seems to do the trick," said Tsuruta. "There is something special about heating with ultrasound—it caused 10-times lower sperm counts than just applying heat."
The researchers found that by rotating 3 Mhz ultrasound around the testes of rats using saline to provide conduction between the ultrasound transducer and skin, the testes were warmed to 37 degrees centigrade. This reduced sperm to a sperm count index of zero.
More research is needed to determine just how effective the procedure is and whether its effect is reversible, according to the researchers.
"Unlike humans, rats remain fertile even with extremely low sperm counts. However, our non-invasive ultrasound treatment reduced sperm reserves in rats far below levels normally seen in fertile men,” said Tsuruta. “However, further studies are required to determine how long the contraceptive effect lasts and if it is safe to use multiple times."