Ultrasound Zap May Be New Form of Birth Control

Jan. 31,2012—, 2012 -- Do not try this at home.

A new animal study, published in the journal Reproductive Biology and Endocrinology, revealed that a couple zaps to the testicles might be the future of contraception.

Researchers from the University of North Carolina at Chapel Hill found that zapping the testicles of rats with a therapeutic ultrasound machine, the type normally used by physical therapists to treat muscle injuries, abolished the germ cells that produce sperm. The best results were seen when the testes underwent two 15-minute zap sessions.

"This caused rat sperm counts to fall far below the [equivalent] range seen in normal fertile men, and this happened in just two weeks," said James Tsuruta, lead author of the study and assistant professor of pediatrics in the laboratories of reproductive biology at UNC Chapel Hill.

"This method dropped sperm counts 10-times lower than just using heat," said Tsuruta. "It's going to be exciting to figure out how this exactly works: if it's safe to use repeatedly, how long it lasts, and if it's reversible."

Of course, more research is needed to see whether the treatment could someday be available to men, but researchers said the zaps show promise as a cheap, reliable and reversible birth control option in the future.

Dr. Paul Turek, director of the Turek Clinic in San Francisco said the research is a "nice feasibility or proof of concept study, [but], as with other studies in medicine, it is always wise to remember that mice are not men."

Women have long been waiting for equality in the birth control realm. Research studies have found that male hormone injections showed some promise in contraception, but many experts say the failure rates are too high to create a reliable contraception method from the research. And, over time, testosterone injections may cause sterilization.

Oral contraception pills for men have also been tested, but nothing has proven safe and effective for consumer use.

Experts say vasectomies continue to be the gold standard for permanent male sterilization. Yet following a vasectomy, it usually takes 20 to 30 ejaculations for a man to clear all viable sperm from the testicles, Dr. Ryan Terlecki, assistant professor of urology at Wake Forest University School of Medicine, wrote in an email to ABC News.

Terlecki cautioned that likewise, with this new method being studied, there may still be an unacceptable "window of opportunity" for viable sperm.

"I would be hesitant to get too excited about the application of this to human reproductive medicine," Terlecki wrote. "It is important to realize that 'less sperm' does not equate to 'zero sperm.'"

There are also other issues to consider when researching this novel zap method, according to Turek. Rat testes are like "lima beans, compared to the kiwi-sized testicles of humans," he said.

"The laws of physics may differ a bit and if the beam misses a single area of the 700 feet of sperm producing tubules in the human testicle, you may have a sperm count," said Turek. "If you have a sperm count in humans, then the possibility of fertility exists. The record low sperm count for natural conception in my practice is 60 sperm (20 million/ml is normal)."

Researchers also must keep the safety of the sperm in mind. If the technique did not eradicate sperm entirely, or if the sperm recovers down the road, in, say, six months, conception is possible and the risk of birth defects and genetic anomalies in the fetus would become a concern.

About 26 percent of U.S. men use one method or another to control fertility, including vasectomies and condoms.

Even though about 70 percent of U.S. couples use some form of contraception, an estimated one million pregnancies end in abortion each year in the U.S. About half of all pregnancies are mistimed or unwanted, and Tsuruta, an assistant professor of pediatrics, said he believes that every child who is born should be wanted.

"The most direct path to reducing the rate of unwanted or mistimed pregnancies is to have women and men sharing responsibility for family planning," said Tsuruta. "One of the goals of research in male birth control is to provide men with more options for controlling their fertility. "We are planning studies on rats to work out issues of safety, reliability and reversibility, before testing the method on men. Safety is paramount."

Despite the potential experts see in the zap, there is still much to be learned about the procedure and any new, widely-available contraception method using the technology is probably a long time away.

"I wouldn't expect a 'scrotal boombox' to hit stores any time soon," Terlecki said.