It's a serious topic, but I couldn't help but laugh at the last line...
Heat Methods of Male Contraception
The deleterious effect of heat on male fertility has been known since ancient times and is mentioned in Hippocratic writings from the fifth century B.C. (Hippocrates & Adams, 1939 p. 312). Much as aspirin was "discovered" in the 1800s from a bark that Native Americans had long been accustomed to chewing to relieve pain, heat methods have been "discovered" in the past century as a method of male contraception.
These methods derive their effectiveness from the simple fact that the testes must be several degrees cooler than normal body temperature in order to maintain proper spermatogenesis (Fukui, 1923; Moore & Oslund, 1923; Rock & Robinson, 1965; Watanabe, 1959). It is still a mystery why this is so, but one biological advantage has been hypothesized. Since men with high fevers are infertile until they are well again (Kandeel & Swerdloff, 1988), newborns will then be more likely to have healthy fathers, thus increasing infant survival rate.
The body provides cooling by enclosing the testes in the scrotum, which performs a twofold function: it keeps the testes outside the body wall; and it creates a heat exchange between incoming and outgoing blood vessels, much like the one in the coils of a refrigerator (Kandeel & Swerdloff, 1988). When this twofold function is impeded, fertility may be impaired.
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Simple Wet Heat
Simple wet heat in the form of hot water, which is inexpensive and available to everyone, was the first systematic contraceptive heat method discovered by the scientific community. In 1946 Dr. M. Voegeli , after more than ten years of experimentation with nine male volunteers, reported on this method. Although time-consuming, the method was perfectly effective and resulted in normal offspring after cessation (Corea, 1985 ch. 9).
Voegeli's program for temporary sterilization is as follows: "A man sits in a [shallow or testes-only] bath of 116 degrees Fahrenheit for forty-five minutes daily for three weeks. Six months of sterility results, after which normal fertility returns. For longer sterility, the treatment is repeated" (Corea, 1985 p. 179). Water at 116˚ Fahrenheit (46.7˚ Celsius) was found to reliably produce at least six months of sterility (Voegeli, 1956). Water at lower temperatures produced shorter periods of infertility; for example, water at 110˚ produced at least four months of infertility.
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Many men’s first reaction to hearing about the wet heat method is to wonder whether 116˚ water would be painful. They do not know exactly how hot 116˚ is but imagine that it could cause a burn.
For comparison, water heaters are often set at 140-160˚ (60-71˚ C). These are painful temperatures that make people jump and can cause a burn in one to six seconds (Bynum, Petri, & Myers, 1998). Public health authorities recommend setting water heaters at 125˚ in households with children. Temperatures below 120˚ are not dangerous for adults.
The adult pain threshold is often quoted as 118˚ (Long et al., 2001). Below 118˚, comfort depends on how much of the body is exposed, and each degree makes a big difference. Most people enjoy full-body baths and hot tubs at 100-103˚ (37.8˚ C to 39.4˚ C) and cannot tolerate 105˚ for long (Long et al., 2001); however, a hot shower is 108-110˚ Fahrenheit (up to 43.3˚ C) (Shouler & Griggs, 2003). Yet a bowl of water at that same temperature, 108-110˚, does not feel particularly hot, even when a delicate body part such as the testes is immersed. Although a bowl of water at 116˚ does feel decidedly hot, it is actually fairly pleasant. The man’s body quickly absorbs the heat away from the skin, and the body part is small enough that the whole body is not being overheated.
Heat tolerance and safety are temperature-dependent as follows:
Fahrenheit Celsius Typical usage Safety/Sensation on skin
140° 60° commercial water heater temp. burns in 1 to 6 seconds; very painful
125° 51.7° top recommended home temp. burns child in 2 minutes; painful
120° 48.9° recommended home faucet temp. uncomfortable; can burn in 10 minutes
118° 47.8° - pain threshold for adults
116° 46.7° testes-only bath for contraception very hot but not painful
110° 43.3° hot shower very warm but not hot
105° 40.5° maximum tolerable bath temp. warm
101° 38.3° comfortable bath or hot-tub temp. warm
Some of the men in Dr. Voegeli ’s studies reportedly supported temperatures up to 125˚. Unless men of the time had higher pain thresholds than modern men, it seems likely that the temperature may have been dipping a degree or two periodically, explaining their ability to tolerate temperatures reported as being 120˚ or above.
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To confirm that the correct temperature is being reached, another inexpensive cooking tool comes in handy: a chocolate-tempering thermometer or a digital waterproof thermometer. Men should also have their infertility confirmed with sperm tests until they are sure they are using the method correctly (or be vulnerable to unhappy surprises).
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The idea of artificial cryptorchidism is simple. Researchers combined two pieces of information:
Raising the temperature of the testes to body temperature (by using insulated underwear or hot water) results in subfertility; and
Men with cryptorchid (undescended) or retractile testes are often infertile (Nistal & Paniagua, 1984).
By putting these two facts together, the pioneers in this area concluded that the testes can be raised to body temperature with less trouble than with insulated underwear by simply maintaining the testes close to the inguinal canal (the tube into which retractile testes withdraw) during waking hours (Mieusset et al., 1985).
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When some of the men in his study refined the retaining underwear by adding a circle of soft material to keep the testes from moving away from the inguinal canal, effectiveness rates shot up, with an average sperm count of 3 million/ml and average motility of 15% (Mieusset et al., 1991), as opposed to values with the old method of 12 million/ml and 22-30% (Mieusset et al., 1987). Using a soft rubber ring was even better, with motile sperm counts consistently below 2 million/ml (average 0.12 million/ml) and the method being ready for contraceptive use sooner (generally within 2-3 months) (Mieusset & Bujan, 1994):
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So with one of Dr. Fahim ’s ideas now on the market, and with cheap sperm tests now available over the counter, has ultrasound’s time finally come? Dr. Min Wang, a senior research associate at the Center for Reproductive Science and Technology at the University of Missouri-Columbia and a close collaborator with Dr. Fahim, says ultrasound is still “basically a good idea” scientifically. He points out that localized methods such as ultrasound are less prone to side effects than hormonal methods (personal communication, M. Wang , November 9, 2005). However, he says, ultrasound is not likely to be developed because at this point “every technology has to have a company behind it” to pay for the clinical trials and the FDA approval process. Ultrasound contraception, unlike the Neutersol sterilant, is not a moneymaker that will attract investors. Unless the public pushes for government- and foundation-sponsored research, ultrasound contraception will have no future.
Next section: Oral Methods of Male Contraception
That's a good one! I've never heard it. 
