(HealthDay News) – A commercially available therapeutic ultrasound generator and transducer can reduce sperm counts in male rats to levels which would result in infertility in humans, according to a study published online January 30 in Reproductive Biology and Endocrinology.

James K. Tsuruta, of the University of North Carolina at Chapel Hill, and colleagues treated anesthetized Sprague-Dawley rats with 1 MHz or 3 MHz ultrasound while varying power, duration, and temperature of treatment.

The researchers found that 3 MHz ultrasound (delivered with 2.2 Watt per square cm power for 15 minutes) was necessary to deplete spermatocytes and spermatids and to significantly reduce epididymal sperm reserves. The 3 MHz ultrasound treatment reduced total epididymal sperm count 10-fold lower than the wet-heat control, and decreased motile sperm counts 1,000-fold lower than wet-heat. Germ cell depletion was most uniform when the therapeutic transducer was rotated to mitigate non-uniformity of the beam field. The lowest sperm count was achieved when the coupling medium (3% saline) was held at 37 degrees Celsius and two consecutive 15-minute treatments of 3 MHz ultrasound (at 2.2 Watt per square cm) were separated by two days.

“The non-invasive nature of ultrasound and its efficacy in reducing sperm count make therapeutic ultrasound a promising candidate for a male contraceptive,” the authors write.

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