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Ultrasound could be a new kind of male contraception
Last reviewed: 01.07.2025
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An ultrasound wave aimed at a man's testicles can stop sperm production, researchers developing a new form of contraception have announced.
Experiments on rats have shown that sound waves can be used to reduce the sperm count in male semen to levels that render men infertile.
In a paper published in Reproductive Biology and Endocrinology, scientists call ultrasound a "promising candidate" for contraception.
However, much more experimentation will be needed before the technique can be used in humans, scientists say.
This idea was first put forward in the 1970s, but only now have researchers from the University of North Carolina, who received a grant for this research from the Bill and Melinda Gates Foundation, begun to put it into practice.
They found that two 15-minute sessions were enough to "significantly reduce" the number of sperm-producing cells and sperm levels.
The greatest effectiveness is achieved when two days pass between sessions and the ultrasound is passed through warm salt water.
There is still some work to be done.
According to the researchers, in men, the "subfertile" state occurs when the sperm count in the seminal fluid drops below 15 million per milliliter.
In rats, this level fell below 10 million sperm per milliliter.
Lead researcher Dr James Tsuruta said: "Further research is needed to determine how long this effect lasts and whether it is safe to use this method repeatedly."
Scientists want to make sure that the effects of ultrasound procedures are reversible, that is, that it is contraception and not sterilization. In addition, it is necessary to establish whether repeated doses create a cumulative effect.
"It's a great idea, but there's a lot more work that needs to be done," said Dr Alan Pacey, senior lecturer in andrology at the University of Sheffield.
In his opinion, the sperm production function should be restored over time, but when this happens, "the sperm may be damaged, and in the future the child may be born with abnormalities."
"The last thing we want is for sperm damage to become chronic," he says.