Update 2014: Based on recent results, it seems harder to get ultrasound to have long-lasting effect in humans and large monkeys, despite excellent results in rats and dogs. The trick has not yet been found. However, ultrasound may have potential as a backup contraceptive. See details below and an update at Parsemus Foundation.
Have you ever had ultrasound treatment for an injured joint? Maybe for a sports injury? For ultrasound contraception, a man (or his doctor) applies 15 minutes of those same painless ultrasound waves to the testes using equipment that’s already common in physical therapists’ offices. In animals, this results in about 6 months of contraception (but can produce permanent sterilization at the right dose). The method is long-acting, localized (nonsytemic—unlike hormones), and nonsurgical.
Ultrasound waves penetrating skin.
The original researcher published studies in many species—and 8 men!—and then saw his work ignored for 30 years. Finally in 2007 two new teams got funding to check it out. Their work has confirmed ultrasound’s effect (in rats and dogs), but we’ll need to know more before there can be widespread use of ultrasound. In particular, how long does the effect last, and does fertility come back even if it’s used many times in a row? In the meantime, anybody who’s willing to buy the equipment can experiment with ultrasound—but at his own risk.
Recent ultrasound studies
The University of North Carolina results in rats (Tsuruta et al, 2012) showed decreased sperm count with ultrasound treatment. University of California researchers (VandeVoort & Tollner, 2014) are finding that it appears to take longer in monkeys than in rats—they’ve done 3 treatments (Monday-Wednesday-Friday) of 30 minutes each—and gotten 6 weeks of effect. An Italian team (Leoci et al.) recently compared different methods in dogs and found that a regimen of three applications of ultrasound at 1 MHz, and 1.5 W/cm2, lasting 5 minutes with an interval of 48 hours was effective as permanent sterilization. The trick for getting long-lasting effect in large adult monkeys, and humans, has yet to be found. A man recently decided to try ultrasound for contraception. He found the effect of ultrasound wearing off within a few months, despite completing at least 10 treatments of 20-30 minutes on a Monday-Wednesday-Friday schedule.
Will funding be forthcoming to study ultrasound contraception further? Sign up for MCIP updates to learn about further developments.
Background & history
Considered on technical and practical merits alone, ultrasound is one of the most promising forms of male contraception. It is technically simple and extremely convenient in that fifteen minutes of ultrasound can result in six months of sterility, and it requires less dedication than heat methods such as artificial cryptorchidism (suspensories) and wet heat. However, it has been neglected until recently; and because it involves a more powerful effect than wet heat, it will require more extensive testing than wet heat or artificial cryptorchidism before it can confidently be recommended for widespread use.
Chattanooga Intelect TranSport, the ultrasound unit currently being used in monkey studies.
For ultrasound contraception, ultrasound waves (very short, inaudible sound waves) are applied to the testes. The ultrasound waves are of the same type and intensity as those used by physical therapists to treat injuries; in fact, the appropriate machine is already sitting in chiropractors’ and physical therapists’ offices around the world.
To use the method, a man first sits in a special chair with his scrotum in a cup of water. In the bottom of the cup is an ultrasound element, which heats the water about as hot as a hot tub. However, heat is not its only method of action (Fahim et al. 1975): it has also been hypothesized that the ultrasound creates an ion exchange between the fluid in the seminiferous tubules and the rete testis, making the environment in the testes inhospitable for sperm formation (Fahim et al. 1977). The method is painless. Some men even report the procedure to be pleasurable (although perhaps this depends on who is applying it!).
Until recently, only one researcher had published extensively on ultrasound contraception: the late Dr. Mostafa S. Fahim, Director of the Center for Reproductive Science and Technology at the University of Missouri at Columbia. In a study of the comparative contraceptive effects of heat, ultrasound, infrared rays, and microwave rays, Dr. Fahim found ultrasound to be the safest and most effective (Fahim et al. 1975). He carried out the first definitive studies on the method of action of ultrasound and its genetic safety in future generations of animals (Fahim 1980, “Male fertility regulation by means of ultrasound” in Regulation of Male Fertility). He secured patents on the concept of ultrasonic contraception (both for humans and for sterilizing pets) and the equipment used to accomplish it (US patents 4078556 and 4077401). Dr. Fahim’s team tested ultrasound in the following species:
- Rats: Fahim 1975, Dumontier 1977, Fahim 1978, Abadir 1979, Abadir 1980, Fahim 1982
- Cats: Fahim 1977, US patent 4073289
- Dogs:Fahim 1977, US patent 4073289
- Monkeys: Fahim 1977, Fahim 1978
- Humans: Fahim 1977, US patents 4078556 and 4077401
In Dr. Fahim’s studies, dosage varied by species, but generally in larger animals, 15 minutes of ultrasound resulted in four to six months of infertility. With two treatments 48 hours apart, six to ten months of infertility can result. Fertility returned gradually once the infertile months were over.
One would think that with so much investment in the idea and such positive results, Dr. Fahim would have continued actively researching ultrasound and working to build the mass of data needed for its acceptance. Yet although Dr. Fahim collaborated with Chinese researchers on using longer and higher doses of ultrasound for permanent sterilization and on using ultrasound to treat epididymal pain and swelling after vasectomy, in 1980 he stopped research on ultrasound as temporary contraception. The reasons included limited funding and strict restrictions on who could participate in his first human trials (Corea 1985, ch. 9). Due to these and other constraints, Fahim moved on to other areas of research.
Mettler Sonicator, the ultrasound unit currently used in rat studies.
Many researchers doubted Dr. Fahim’s results, partly because a 1988 paper seemed to contradict them (Urry et al. 1988). However, although the study was published in 1988, it actually reported on a study conducted in 1973-76, before many details of Dr. Fahim ‘s technique were available. Upon careful reading, several of its techniques were clearly different—for example, Dr. Urry exposed the animal’s whole hind end to the ultrasound water bath, and, not surprisingly, could not find a power level that was effective without burning the bony, delicate tail structure (ouch!).
As is so often true for innovative and creative researchers, Dr. Fahim received little respect or recognition during his lifetime. He passed away in 1995 and did not live to see the day in 2003, after almost 20 years of work by his team, that the FDA approved his injectable sterilant for dogs. This nonsurgical sterilant is not appropriate for humans because it may impact testosterone levels, but it is already being used as an alternative to surgical sterilization for pets.
Thus one of Dr. Fahim’s ideas is now approved by the U.S. FDA and on the market in several countries, which indicates that Dr. Fahim’s research should have been taken more seriously. Furthermore, cheap sperm tests now available over the counter, making it easy for men to see whether a method like ultrasound is working. So has ultrasound’s time finally come?
Ultrasound contraception, unlike the dog sterilant, is not a moneymaker that will attract investors. Government- and foundation-sponsored research is necessary for it to have a future. For 25 years none was forthcoming, but now there is reason for hope.
In 2007, the Parsemus Foundation, a small new foundation with a focus on male contraception, chose ultrasound for one of its first research grants. The study attempted to duplicate Dr. Fahim’s results in rats, since reproducibility of results is a basic tenet of science. The team of nonprofit and academic investigators (from Family Health International and the University of North Carolina) carefully studied Dr. Fahim’s publication and patents, as well as the conflicting publication by Urry, to try to determine which parameters are key for success. In initial pilot studies, they saw definite effect, but not as strong an effect as reported by Dr. Fahim. For the final pilot study in 2009, they changed several variables, and they saw increased effect—which they reported in a poster presentation at the 2009 North American Testis Workshop (order here). Encouraged to have found a combination that worked, the researchers won a Bill & Melinda Gates Foundation Grand Challenges Explorations grant to continue their study, which wraps up in spring of 2011.
But would knowing it works in rats be good enough? Based on these positive initial results in rats, the same foundation funded a small study at a the University of California to confirm Dr. Fahim’s results in monkeys. If both respected university and nonprofit teams are able to confirm a consistent ultrasound effect, larger foundations and funders must begin to take the method seriously, as it would offer the first truly non-invasive long-term method for men.
Meanwhile, unbeknownst to the U.S. foundation and researchers, an Italian team had taken interest in ultrasound. Raffaella Leoci of the University of Bari veterinary department first got curious about ultrasound when a friend started working for a German ultrasound manufacturer and challenged her to come up with other uses for the machines. With a little digging, she found Dr. Fahim’s research—and since southern Italy has a stray dog problem, she wondered whether ultrasound could be used to sterilize dogs without subjecting them to the trauma of surgery.
Vetri-Son Portable, the ultrasound unit currently used in dog studies.
Leoci and her colleagues tried three treatments in a row, one every other day, on five dogs. When semen analysis was done at 2 weeks, there were no sperm. They published their results in a veterinary journal in 2009, but MCIP and the U.S. teams didn’t become aware of their work until the next year, when the Italian researchers attended the Alliance for Contraception in Cats and Dogs conference, presenting a poster of further results in 25 dogs. Again, the treatment was five minutes a day, every other day—and based on the way the testes looked when they removed them at day 20, they believe they got permanent contraception from that treatment, making it a viable alternative to vasectomy. The Parsemus Foundation, the small foundation that funded the first rat study, is now funding the Italian researchers to continue their work.
One major difference in the technique the Italian team is using is they are rubbing the transducer around the testes by hand, using ultrasound gel like in physical therapy, rather than using a cup of water like Prof. Fahim did. The rat researchers are continuing with the cup technique, since it is working for them. They are also using the higher of two frequency settings (3 MHz), since they found it was more effective—whereas in monkeys, humans, and dogs, the lower-frequency waves (1 MHz or 1.5 MHz) penetrate the larger testes better.
An important priority for subsequent ultrasound research—which is beyond the budget of the foundation which has funded ultrasound research so far—is the question of whether, and how, fertility returns after multiple uses of the method (Kandeel & Swerdloff 1988). For example, could a man safely rely on ultrasound for contraception for five or ten years? It is also important to confirm the results of previous safety studies. This will require the involvement of larger funders.
When a new contraceptive is introduced, it is standard practice to approve it for short-term use and then extend the approval as long-term data on the original study subjects becomes available, as was done with other new contraceptives (such as the Mirena IUD for women). Funders should support larger tests as soon as the results of the rat and monkey studies are known, so that longer and longer uses of ultrasound can gradually be approved (or not approved, as the case may be). Public input will be crucial to making this happen.
If you are considering trying ultrasound for contraception
Ultrasound is a new method, and those not willing to be guinea pigs and take chances with their own fertility should wait for the results of further studies, especially now that we’ve seen in the dog studies that multiple treatments a few days apart may have permanent effect. There is nothing preventing men from buying a $1,300 ultrasound machine online and trying it. However, before doing that, men should have read all of Dr. Fahim’s patents (and have enough biology background to understand them), his 1977 and 1978 papers listed above, the Italian researchers’ poster presentation, and the reviews of heat methods by Kandeel and Swerdloff (which will require going to the medical library) and Setchell (this one is free). Only after reading all of those will one have a better sense of what is known and not known and be able to make a more informed decision.
Note 2016: Link broken? Doing historical research? Try the previous (2011) archived version of our site if you need a particular link or reference.