Ultrasound as a reversible contraceptive for men might not be too far away if the efforts of US scientists bear fruit.
In any case the Bill & Melinda Gates Foundation seems impressed and has announced a grant of US$100,000 towards the project.
James Tsuruta and Paul Dayton of the University of North Carolina, Chapel Hill in the U.S. will now be able to go for more clinical trials to study the ability of ultrasound to temporarily deplete testicular sperm counts.
Based on early work, the two researchers seem to believe a blast of ultrasound to the testes can safely stop sperm production for six months.
Lead researcher Dr James Tsuruta said: "We think this could provide men with up to six months of reliable, low-cost, non-hormonal contraception from a single round of treatment.
"Our long-term goal is to use ultrasound from therapeutic instruments that are commonly found in sports medicine or physical therapy clinics as an inexpensive, long-term, reversible male contraceptive suitable for use in developing to first world countries."
Once the testis has stopped producing sperm and all "sperm reserves" have been depleted, explain the researchers, the man will be temporarily infertile.
The Bill & Melinda Gates Foundation has announced 78 grants of US$100,000 each in the latest round of Grand Challenges Explorations. Grants include the development of a low-cost cell phone microscope to diagnose malaria, study of the strategic placement of insect-eating plants to reduce insect-borne diseases, and investigation of nanoparticles to release vaccines when they come in contact with human sweat. The grants support research across 18 countries and six continents.