An alternative male contraceptive method involves heating the testicles so that they cannot produce sperm. Sperm are best produced at a temperature slightly below body temperature. The muscles around a male's scrotum involuntarily tighten if the man's body temperature drops, and they loosen, allowing the testes to hang, if the body temperature rises. This is the body's way of keeping the sperm at an ideal temperature.[citation needed] This means that sperm production can be disrupted with increased temperature.[1] Some suggest exposure to high temperatures (116°F equal to 47°C) can affect fertility for months.[2]
Male thermal contraceptive methods (MTC) derive their effectiveness from the alteration of the thermoregulatory function of the scrotum.[3] When this function is altered – by wearing tight underwear,[4] being exposed to a high outside temperature, or by developing a fever, fertility may be impaired.
Methods used include hot water applied to the scrotum, heat generated by ultrasound, and artificial cryptorchidism (holding the testicles inside the abdomen) using specialized briefs. One of the initial experiments resulted in partial infertility lasting more than four years.[5] Initial experiments suggest it is effective and safe, though there have not been long-term studies to determine if it has any side effects on the body after reversal.
History
The deleterious effect of hyperthermia on male fertility has been known since ancient times.[citation needed] A history of testicular descent problems (cryptorchidism) or professional practices that lead to elevated scrotal temperature and even fever have been known factors of reduced fertility.[6] But it is from the 19th century onwards that the scientific community started to carry out research to better understand the phenomenon.
In the 1930s, physician Marthe Voegeli[7] explored the role of heat in male sterilization. She conducted experiments on the relationship between heat and spermatogenesis. She found that exposing the testicles to high temperatures in hot baths altered fertility. Sperm concentrations in the volunteers decreased so much so that they were considered infertile. She was the first scientist to popularize this alternative method of contraception for men. Thermal dependence of spermatogenesis was studied in 1941 with external heat such as hot baths or saunas with temperatures above 40°C over short periods of exposure.[8][9]
The thermal dependence of spermatogenesis was confirmed in various studies carried out between 1950 and 1970 by Doctors Watanabe and Robinson.[10][11][12][13] In the 1960s Studies have been carried out with daily exposure of the testicles to less intense heat, around 37°C, a temperature that is close to that of the body.[14]
In 1999, a contraceptive device using body heat was patented by Andreas Schopp.[15]
How it works
The production of sperm can be disrupted with a rise in temperature.[16]
Thermal methods involve heating the testicles so that sperm production is slowed down. The spermatozoa are thus produced at a slightly lower temperature than that of the body, 1 to 2°C below 37°C.
The cremaster muscle covers the testicles. It works involuntarily. Its role is to bring the testicles down if the body temperature rises or to raise them if the body temperature drops. This process allows it to regulate the temperature of the testicles and to keep it several degrees lower than that of the body in order to enable an ideal spermatogenesis.[17][18]
Other effects have also been observed, such as a decrease in motility and an alteration in the morphological characteristics of the spermatozoa that are produced.[18][19][20][21]
Some suggest that exposure to high temperatures (47°C) can affect fertility for months.[3]
Efficacy
Thermal methods do not cause azoospermia, but a reduction of the spermatozoa[22] below the contraceptive threshold considered to be effective.
This contraceptive threshold was defined in 2007 for male thermal, chemical and hormonal contraception methods. It corresponds to 1 million spermatozoa per milliliter per ejaculate.[23][24][25]
The only method that has been tested on enough volunteers to establish that the effectiveness of thermal male contraception is satisfactory is the artificial cryptorchidism method with testicular ascent using a specific device. During the clinical studies,[24] 50 couples were followed over 537 cycles of pregnancy. Only one resulted in a pregnancy due to a misuse of the technique. The Pearl Index would therefore be less than 0.5 and this contraception method can be considered effective according to the standards of the World Health Organisation (WHO).
Adverse effects
The maximum limit of exposure to heat is around 45°C, which causes the coagulation of intracellular proteins on living cells. However, exposure above 41°C for short periods of time may be used, as has been the case for scientific studies on the effect of hot baths.[26]
In the case of artificial cryptorchidism or thermal insulation of the testicles, the use of a temperature close to that of the body (37°C) has made it possible to increase the time of exposure in order to slow down the spermatogenesis process over longer periods, 4 years in a row at most. To date, only a decrease in testicular volume by a few percents has been observed during the contraceptive period. There is no evidence of an increased risk of testicular torsion. However, it has been shown that the nuclear quality of the spermatozoa was altered during the phase of inhibition of the spermatogenesis, but that this was reversible 3 months after the subject stops practicing artificial cryptorchidism.[27] This finding should be taken into account when using this contraception method, during the inhibition phase and for 3 months after treatment discontinuation.[24]
Methods
Hot baths
Within a few months of daily exposure, the number of spermatozoa drops provided the temperature is higher than that of the body: 38 to 46°C instead of 37°C.[10][12][9][16][8][28][29][30]
Warming the testicles with body heat by keeping them in the inguinal sack for several hours a day reduces sperm production below the contraceptive threshold of 1 million/ml.[10][19][21][34][35][36][13][27]
However, it was not until 50 years later, in 1991, that the first study reporting the contraceptive effect of heat on men was published: andrologists Roger Mieusset and Jean-Claude Soufir were the first to get results with the artificial cryptorchidism method[3] (testicles held inside the inguinal sack) with the use of suited devices.
Thermal insulation of the testis
A surgical intervention causes the testicles to be held in the inguinal sack.[34]
Heating devices
As of 1990 various techniques had been considered, such as an insulating bag with heating elements in contact with the scrotum.[37] Wearing a device that presses the man's testicles against his body on a daily basis can raise their temperature by 2°C and thus slow down sperm production.[38] To be effective, the device must be worn daily (approximately 15 hours per day) for at least 3 months, which is equivalent to the sperm's life cycle. This allows the contraceptive threshold of one million per millilitre of sperm to be temporarily reached (compared to an average of 15 to 60 million).[39] Practitioners should do pre- and post-usage testing to check their sperm counts.[39]
Heating underwear
The heating briefs are one of the available devices. This method was invented and is prescribed by Doctor Mieusset at the University Hospital of Toulouse.[40] In 2019, a French news channel reported that "only about twenty men were wearing this contraceptive garment in France".[38] It is not sold on the market and a poorly handcrafted design can cause discomfort or irritation.[40] Other "do-it-yourself" models called "jock-strap" or "bra" also exist.[41] In 2022, 68% of respondents had adopted the new method after less than two weeks, despite initial concerns. After they had completely switched (n = 59), they gave a significantly improved sexual satisfaction compared to the previous method of contraception[42]
Silicone used to induce artificial cryptorchidism.
Silicone ring
Another available device is the silicone ring. Invented and patented by Maxime Labrit, a French nurse,it is available for purchase on the Internet for a few dozen euros.[39]
Ultrasound
One method under investigation is ultrasound, which involves the application of high-frequency sound waves to animal tissue, which in turn absorb the sound waves' energy as heat. The possibility for ultrasound's use for contraception is based on the idea that briefly heating the testes can halt sperm production, leading to temporary infertility for about six months. Additionally, ultrasound could affect cells' absorption rates of ions, which itself could create an environment unfavorable to spermatogenesis. Its extremely localized effects on animal tissues make ultrasound an attractive candidate for research. So far studies have been performed on non-human animals, such as dogs,[17] as well as on humans for temporary or permanent contraception[43][44][45] which provides a method to "temporarily or permanently suppress spermatogenesis while causing the subject substantially no discomfort.".
"This apparatus provides for the controlled application of ultrasonic vibrations to the testes of human males in such a way to cause temporary or permanent sterility selectively as desired without affecting the subject's sex drive, his sex characteristics or general health."[46]
↑ «Contraception masculine: par la chaleur - La Santé des Femmes et Style de Vie », La Santé des Femmes et Style de Vie, 20 janvier 2015 (read online [archive], consulted on 19 March 2018).
1 2 Robert S. Hotchkiss et John Macleod, "The effect of hyperpyrexia upon spermatozoa counts in men", Endocrinology, vol. 28, no 5, 1er mai 1941, p. 780–784 (ISSN 0013-7227, DOI 10.1210/endo-28-5-780, read online [archive], consulted on 22 February 2019).
1 2 Brown-Woodman PDC, Post EJ, Gasc GC, White IG. The effect of a single sauna exposure on spermatozoa. Arch Androl. 1984;12:9–15.
1 2 3 Watanabe A. The effect of heat on human spermatogenesis. Kyushu J Med Sci.1959;10:101–117.
↑ Robinson D, Rock J, Menkin MF. Control of human spermatogenesis by induced changes of intrascrotal temperature. J Am Med Ass. 1968;204:80–87.
1 2 Rock J, Robinson D. Effect of induced intrascrotal hyperthermia on testicular function in man. Am J Obstet Gynec. 1965;93:793–801.
1 2 Wang C, McDonald V, Leung A, Superlano L, Berman N, Hull L, et al.Effect of increased scrotal temperature on sperm production in normal men. Fertil Steril. 1997;68(2):334–339.
↑ Robinson D, Rock J. Intrascrotal hyperthermia induced by scrotal insulation: effect on spermatogenesis. Obstet Gynecol. 1967;2:217–23.
1 2 F. R. Kandeel et Swerdloff R. S.,"Role of temperature in regulation of spermatogenesis and the use of heating as a method for contraception", Fertil Steril, vol. 49, no 1, janvier 1988, p. 1–23 (PMID3275550).
1 2 R. Mieusset, «Cryptorchidie et température testiculaire», Andrologie, 1995, p. 317-325 (read online [archive]).
1 2 Mieusset R, Bujan L, Mansat A, Pontonnier F, Grandjean H. Hyperthermia and human spermatogenesis: enhancement of the inhibitory effect obtained by 'artificial cryptorchidism'. Int J Androl. 1987;10:571–580.
↑ Mieusset R, Bujan L, Mansat A, Pontonnier F, Grandjean H. Effect of artificial cryptorchidism on sperm morphology. Fertil Steril. 1987;47:150–155.
1 2 Shafik A. Testicular suspension as a method of male contraception: technique and results. Adv Contr Deliv Syst. 1991;VII:269–279.
↑ World Health Organization Task Force on Methods for the Regu- lation of Male Fertility [archive], Gui-Yuan Z, Guo-Zhu L, et al. Contraceptive efficacy of testosterone-induced azoospermia in normal men. Lancet 1990;336:955-959.
1 2 3 Jean-Claude Soufir, "Hormonal, chemical and thermal inhibition of spermatogenesis: contribution of French teams to international data with the aim of developing male contraception in France", Basic and Clinical Andrology, vol. 27, 13 janvier 2017, p. 3 (ISSN2051-4190, DOI10.1186/s12610-016-0047-2, read online [archive], consulted on 19 March 2018)
↑ «Contraception masculine: l'avenir est dans le slip… chauffant», ladepeche.fr, 12 January 2018 (read online [archive], consulted on 19 March 2018).
1 2 Ahmad G, Moinard N, Lamare C, Mieusset R, Bujan L. Mild testicular and epididymal hyperthermia alters sperm chromatin integrity in men. Fertil Steril. 2012;97:546–553.
↑ Procope BJ. Effect of repeated increase of body temperature on human sperm cells. Int J Fertil. 1965;10:333–339.
↑ MIEUSSET R., BUJAN L.: Testicular heating and its possible contributions to male infertility: a review. Int. J. Androl., 1995; 18: 169-184.
↑ Zhu H, Cui Y, Xie J, Chen L, Chen X, Guo X, et al.Proteomic analysis of testis biopsies in men treated with transient scrotal hyperthermia reveals the potential targets for contraceptive development. Proteomics. 2010;10:3480–3493.
↑ «Contraceptions masculines non déférentielles: revue de la littérature | Urofrance» [archive], on www.urofrance.org (consulted on 1 March 2019).
↑ R. Mieusset, L. Bujan, A. Mansat et F. Pontonnier, «Hyperthermie scrotale et infécondité masculine», Progrès en Urologie, 1992, p. 31-36 (read online [archive]).
↑ Jean-Claude Soufir et Roger Mieusset, «Guide pratique d'une contraception masculine hormonale ou thermique», Andrologie, vol. 22, no 3, 2012, p. 211–215 (DOI10.1007/s12610-012-0192-1, read online [archive]).
1 2 SHAFIK A.: Contraceptive efficacy of polyester-induced azoospermia in normal men. Contraception, 1992; 45: 439-451.
↑ MIEUSSET R., BUJAN L.: The potential of mild testicular heating as a safe, effective and reversible contraceptive method for men. Int. J. Androl., 1994; 17: 186-191.
↑ Moeloek N. Polyester sling scrotal cover induces oligozoospermia in normal Indonesian men. Med J Indones. 1995;4:225–230.
↑ Wayne T. Walston, "Male contraceptive device", WIPO, 5 septembre 1990 (read online [archive], consulted on 19 March 2018).
↑ Fahim, M. S., Zuhal Fahim, James Harman, Ian Thompson, Joseph Montie, and D. G. Hall. "Ultrasound as a new method of male contraception." Fertility and sterility 28, no. 8 (1977): 823-831
↑ Fahim, M. S. "Male fertility regulation by means of ultrasound." Regulation of male fertility (1980): 219-230
A testicle or testis is the male gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testicles are to produce both sperm and androgens, primarily testosterone. Testosterone release is controlled by the anterior pituitary luteinizing hormone, whereas sperm production is controlled both by the anterior pituitary follicle-stimulating hormone and gonadal testosterone.
Vasectomy is an elective surgical procedure that results in male sterilization, often as a means of permanent contraception. During the procedure, the male vasa deferentia are cut and tied or sealed so as to prevent sperm from entering into the urethra and thereby prevent fertilization of a female through sexual intercourse. Vasectomies are usually performed in a physician's office, medical clinic, or, when performed on a non-human animal, in a veterinary clinic. Hospitalization is not normally required as the procedure is not complicated, the incisions are small, and the necessary equipment routine.
Cryptorchidism, also known as undescended testis, is the failure of one or both testes to descend into the scrotum. The word is from Ancient Greek κρυπτός (kryptos) 'hidden' and ὄρχις (orchis) 'testicle'. It is the most common birth defect of the male genital tract. About 3% of full-term and 30% of premature infant boys are born with at least one undescended testis. However, about 80% of cryptorchid testes descend by the first year of life, making the true incidence of cryptorchidism around 1% overall. Cryptorchidism may develop after infancy, sometimes as late as young adulthood, but that is exceptional.
The cremaster muscle is a paired structure made of thin layers of striated and smooth muscle that covers the testicles and the spermatic cords in human males. It consists of the lateral and medial parts. Cremaster is an involuntary muscle, responsible for the cremasteric reflex; a protective and physiologic superficial reflex of the testicles. The reflex raises and lowers the testicles in order to keep them protected. Along with the dartos muscle of the scrotum, it regulates testicular temperature, thus aiding the process of spermatogenesis.
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testicle. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. The primary spermatocyte divides meiotically into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa and four haploid cells.
Seminiferous tubules are located within the testicles, and are the specific location of meiosis, and the subsequent creation of male gametes, namely spermatozoa.
Spermatocele is a fluid-filled cyst that develops in the epididymis. The fluid is usually a clear or milky white color and may contain sperm. Spermatoceles are typically filled with spermatozoa and they can vary in size from several millimeters to many centimeters. Small spermatoceles are relatively common, occurring in an estimated 30 percent of males. They are generally not painful. However, some people may experience discomfort such as a dull pain in the scrotum from larger spermatoceles. They are not cancerous, nor do they cause an increased risk of testicular cancer. Additionally, unlike varicoceles, they do not reduce fertility.
Testicular atrophy is a medical condition in which one or both testicles diminish in size and may be accompanied by reduced testicular function. Testicular atrophy is not related to the temporary shrinkage of the surrounding scrotum, which might occur in response to cold temperature.
Acrosin is a digestive enzyme that acts as a protease. In humans, acrosin is encoded by the ACR gene. Acrosin is released from the acrosome of spermatozoa as a consequence of the acrosome reaction. It aids in the penetration of the Zona Pellucida.
A varicocele is, in a man, an abnormal enlargement of the pampiniform venous plexus in the scrotum; in a woman, it is an abnormal painful swelling to the embryologically identical pampiniform venous plexus; it is more commonly called pelvic compression syndrome. In the male varicocele, this plexus of veins drains blood from the testicles back to the heart. The vessels originate in the abdomen and course down through the inguinal canal as part of the spermatic cord on their way to the testis. Varicoceles occur in around 15% to 20% of all men. The incidence of varicocele increase with age.
Azoospermia is the medical condition of a man whose semen contains no sperm. It is associated with male infertility, but many forms are amenable to medical treatment. In humans, azoospermia affects about 1% of the male population and may be seen in up to 20% of male infertility situations in Canada.
Male contraceptives, also known as male birth control, are methods of preventing pregnancy by interrupting the function of sperm. The main forms of male contraception available today are condoms, vasectomy, and withdrawal, which together represented 20% of global contraceptive use in 2019. New forms of male contraception are in clinical and preclinical stages of research and development, but as of 2024, none have reached regulatory approval for widespread use.
Male infertility refers to a sexually mature male's inability to impregnate a fertile female. In humans, it accounts for 40–50% of infertility. It affects approximately 7% of all men. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity. More recently, advance sperm analyses that examine intracellular sperm components are being developed.
Spermatogenesis arrest is known as the interruption of germinal cells of specific cellular type, which elicits an altered spermatozoa formation. Spermatogenic arrest is usually due to genetic factors resulting in irreversible azoospermia. However some cases may be consecutive to hormonal, thermic, or toxic factors and may be reversible either spontaneously or after a specific treatment. Spermatogenic arrest results in either oligospermia or azoospermia in men. It is quite a difficult condition to proactively diagnose as it tends to affect those who have normal testicular volumes; a diagnosis can be made however through a testicular biopsy.
Adjudin (AF-2364) is a drug which is under development as a potential non-hormonal male contraceptive drug, which acts by blocking the production of sperm in the testes, but without affecting testosterone production. It is an analogue of the chemotherapy drug lonidamine, an indazole-carboxylic acid, and further studies continue to be conducted into this family of drugs as possible contraceptives.
Semen quality is a measure of male fertility, a measure of the ability of sperm in semen to accomplish fertilization. Semen quality involves both sperm quantity and quality. Semen quality is a major factor for fertility.
In most terrestrial mammals, the scrotum or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin containing the external spermatic fascia, testicles, epididymides, and vasa deferentia. The scrotum will usually tighten when exposed to cold temperatures.
Vasectomy reversal is a term used for surgical procedures that reconnect the male reproductive tract after interruption by a vasectomy. Two procedures are possible at the time of vasectomy reversal: vasovasostomy and vasoepididymostomy. Although vasectomy is considered a permanent form of contraception, advances in microsurgery have improved the success of vasectomy reversal procedures. The procedures remain technically demanding and may not restore the pre-vasectomy condition.
FNA mapping is an application of fine-needle aspiration (FNA) to the testis for the diagnosis of male infertility. FNA cytology has been used to examine pathological human tissue from various organs for over 100 years. As an alternative to open testicular biopsy for the last 40 years, FNA mapping has helped to characterize states of human male infertility due to defective spermatogenesis. Although recognized as a reliable, and informative technique, testis FNA has not been widely used in U.S. to evaluate male infertility. Recently, however, testicular FNA has gained popularity as both a diagnostic and therapeutic tool for the management of clinical male infertility for several reasons:
The testis is an ideal organ for evaluation by FNA because of its uniform cellularity and easy accessibility.
The trend toward minimally invasive procedures and cost-containment views FNA favorably compared to surgical testis biopsy.
The realization that the specific histologic abnormality observed on testis biopsy has no definite correlation to either the etiology of infertility or to the ability to find sperm for assisted reproduction.
Assisted reproduction has undergone dramatic advances such that testis sperm are routinely used for biological pregnancies, thus fueling the development of novel FNA techniques to both locate and procure sperm.
Dr. Paul J Turek is an American physician and surgeon, men's reproductive health specialist, and businessman. Turek is a recent recipient of a National Institutes of Health (NIH) grant for research designed to help infertile men become fathers using stem cells.
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