出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/07/07 18:30:13」(JST)
Vasectomy | |
---|---|
Background | |
Birth control type | Sterilization |
First use | 1899 (experiments from 1785)[1] |
Failure rates (first year) | |
Perfect use | 0.10%[2] |
Typical use | 0.15%[2] "Vas-Clip" nearly 1% |
Usage | |
Duration effect | Permanent |
Reversibility | Possible, but expensive. |
User reminders | Two consecutive negative semen specimens required to verify azoospermia. |
Clinic review | All |
Advantages and disadvantages | |
STD protection | No |
Benefits | No need for general anesthesia. Lower cost/less invasive than tubal ligation for women. |
Risks | Temporary local inflammation or swelling of the testes. Long-term genital pain (PVPS). Moderately increased risk of prostate cancer, and more lethal form of this.[3] |
Vasectomy is a surgical procedure for male sterilization and/or permanent contraception. During the procedure, the male vasa deferentia are severed and then tied/sealed in a manner so as to prevent sperm from entering into the seminal stream (ejaculate) and thereby prevent fertilization. Vasectomies are usually performed in a physician's office, medical clinic, or, when performed on an animal, in a veterinary clinic— hospitalization is not normally required as the procedure is not complicated, the incisions small, and the necessary equipment routine.
There are several methods by which a surgeon might complete a vasectomy procedure, all of which occlude (i.e. "seal") at least one side of each vas deferens. To help reduce anxiety and increase patient comfort, men who have an aversion to needles may consider a "no-needle" application of anesthesia while the "no-scalpel" or "open-ended" techniques help to accelerate recovery times and increase the chance of healthy recovery.
Due to the simplicity of the surgery, a vasectomy usually takes less than thirty minutes to complete. After a short recovery at the doctor's office (usually less than an hour), the patient is sent home to rest. Because the procedure is minimally invasive, many vasectomy patients find that they can resume their typical sexual behavior within a week, and do so with little or no discomfort.
Because the procedure is considered a permanent method of contraception and is not easily reversed, men are usually counseled/advised to consider how the long-term outcome of a vasectomy might affect them both emotionally and physically. The procedure is not often encouraged for young single men as their chances for biological parenthood are thereby more or less permanently reduced to almost zero by it. It is seldom performed on dogs (castration, a different procedure, remains the preferred reproductive control option for canines) but is regularly performed on bulls.[4]
The traditional incision approach of vasectomy involves numbing of the scrotum with local anesthetic (although some men's physiology may make access to the vas deferens more difficult in which case general anesthesia may be recommended) after which a scalpel is used to make two small incisions, one on each side of the scrotum at a location that allows the surgeon to bring each vas deferens to the surface for excision. The vasa deferentia are cut (sometimes a section may be removed altogether), separated, and then at least one side is sealed by ligating (suturing), cauterizing (electrocauterization), or clamping.[5] There are several variations to this method that improve healing, effectiveness, and which help mitigate long-term pain such as post-vasectomy pain syndrome (PVPS) or epididymitis.
The following vasectomy methods have purportedly had a better chance of later reversal but have seen less use by virtue of known higher failure rates (i.e., recanalization).
An earlier clip device, the VasClip, is no longer on the market, due to unacceptably high failure rates.[14][15][16]
The VasClip method, though considered reversible, has had a higher cost and resulted in lower success rates. Also, because the vasa deferentia are not cut and/or tied with this method, it could technically be classified as other than a vasectomy. Vasectomy reversal (and the success thereof) was conjectured to be higher as it only required removing the Vas-Clip device. This method achieved limited use, and scant reversal data are available.[16]
Both vas occlusion techniques require the same basic patient setup: local anesthesia, puncturing of the scrotal sac for access of the vas, and then plug and/or injected plug occlusion. The success of the aforementioned vas occlusion techniques is not clear and data are still limited. Studies have shown, however, that the time to achieve sterility is longer than the more prominent techniques mentioned in the beginning of this article. The satisfaction rate of patients undergoing I.V.D. techniques has a high rate of satisfaction with regard to the surgery experience itself.[13]
Sexual intercourse can usually be resumed in about a week (depending on recovery); however, pregnancy is still possible as long as the sperm count is above zero. Another method of contraception must be relied upon until a sperm count is performed either two months after the vasectomy or after ten to twenty ejaculations have occurred.[19]
After a vasectomy, contraceptive precautions must be continued until azoospermia is confirmed. Usually two semen analyses at three and four months are necessary to confirm azoospermia. The British Andrological Society has recommended that a single semen analysis confirming azoospermia after sixteen weeks is sufficient.[citation needed]
Vasectomy ensures that in most cases the patient will be sterile after confirmation of success following surgery. The procedure is regarded by the medical profession as permanent because vasectomy reversal is costly and often does not restore the male's sperm count and/or sperm motility to prevasectomy levels.
Men with vasectomies have a very small (nearly zero) chance of successfully impregnating a woman, but a vasectomy has no effect on rates of sexually transmitted infections.
After vasectomy, the testes remain in the scrotum where Leydig cells continue to produce testosterone and other male hormones that continue to be secreted into the blood-stream. Some studies have found that sexual desire after vasectomy may be somewhat diminished.[20][21]
When the vasectomy is complete, sperm can not exit the body through the penis. Sperm are still produced by the testicles, but they are soon broken down and absorbed by the body. Much fluid content is absorbed by membranes in the epididymis, and much solid content is broken down by the responding macrophages and reabsorbed via the blood stream. Sperm is matured in the epididymis for about a month before leaving the testicles. After vasectomy, the membranes must increase in size to absorb and store more fluid; this triggering of the immune system causes more macrophages to be recruited to break down and reabsorb more solid content. Within one year after vasectomy, sixty to seventy per cent of vasectomized men develop antisperm antibodies.[22] In some cases, vasitis nodosa, a benign proliferation of the ductular epithelium, can also result.[23][24] The accumulation of sperm increases pressure in the vas deferens and epididymis. The entry of the sperm into the scrotum can cause sperm granulomas to be formed by the body to contain and absorb the sperm which the body will treat as a foreign biological substance (much like a virus or bacterium).[10]
Early failure rates, i.e. pregnancy within a few months after vasectomy, typically result from unprotected sexual intercourse too soon after the procedure while some sperm continue to pass through the vasa deferentia. Most physicians and surgeons who perform vasectomies recommend one (sometimes two) postprocedural semen specimens to verify a successful vasectomy; however, many men fail to return for verification tests citing inconvenience, embarrassment, forgetfulness, or certainty of sterility.[25] In January 2008, the F.D.A. cleared a home test called SpermCheck Vasectomy that allows patients to perform postvasectomy confirmation tests themselves;[26] however, compliance for postvasectomy semen analysis in general remains low.
Late failure, i.e. pregnancy following spontaneous recanalization of the vasa deferentia, has also been documented.[27] The Royal College of Obstetricians and Gynaecologists states there is a generally agreed-upon rate of late failure of about one in 2000 vasectomies— vastly better than tubal ligations for which the failure rate is one in every 200 to 300 cases.[28]
A 2005 systematic review of twenty-eight studies including both early failures and late failures described a total of 183 failures or recanalizations from approximately 43,642 vasectomy patients (0.4%), and twenty studies in the same review described sixty pregnancies after 92,184 vasectomies (0.07%).[29]
Short-term possible complications include infection, bruising and bleeding into the scrotum resulting in a collection of blood known as a hematoma. A study in 2012 demonstrated an infection rate of 2.5% postvasectomy.[30] The stitches on the small incisions required are prone to irritation, though this can be minimized by covering them with gauze or small adhesive bandages. The primary long-term complications are chronic pain conditions or syndromes that can affect any of the scrotal, pelvic and/or lower-abdominal regions, collectively known as post-vasectomy pain syndrome. Though vasectomy results in increases in circulating immune complexes, these increases are transient. Data based on bestial and human studies indicate these changes do not result in increased incidence of atherosclerosis. The risk of prostate and testicular cancer is not affected by vasectomy.[31]
Long-term postvasectomy pain is experienced at a frequency which ranges between 15% and 33% of vasectomy patients.[32]
Post-vasectomy pain syndrome (P.V.P.S.) is a chronic and sometimes debilitating condition that may develop immediately or several years after vasectomy.[33] One survey cites studies that estimate incidence at one case in every ten to thirty vasectomies.[34] The pain can be constant orchialgia or epididymal pain (epididymitis), or it can be pain that occurs only at particular times such as with sexual intercourse, ejaculation, or physical exertion.[10]
Researchers have reported an association between vasectomy and primary progressive aphasia (P.P.A.), a rare variety of frontotemporal dementia. The rate of vasectomy in P.P.A. patients was 40% (19/47) vs. 16% (9/57) in normal controls. This difference met statistical significance (p=0.02). The study also found that there was a younger age of P.P.A. onset for patients who had undergone vasectomy (58.8 years of age vs. 62.9 years; p=0.03).[35][36] However, some doubt has been cast on the reality of this association.[37]
Although men considering vasectomies should not think of them as reversible, and most men and their partners are satisfied with the operation,[38] [39] life circumstances and outlooks can change, and there is a surgical procedure to reverse vasectomies using vasovasostomy (a form of microsurgery first performed by Earl Owen in 1971[40][41]). Vasovasostomy is effective at achieving pregnancy in a variable percentage of cases, and total out-of-pocket costs in the United States are often upwards of [42] The typical success rate of pregnancy following a vasectomy reversal is around 55% if performed within 10 years, and drops to around 25% if performed after 10 years.[43] After reversal, sperm counts and motility are usually much lower than pre-vasectomy levels. There is evidence that men who have had a vasectomy may produce more abnormal sperm, which would explain why even a mechanically successful reversal does not always restore fertility.[44][45] The higher rates of aneuploidy and diploidy in the sperm cells of men who have undergone vasectomy reversal may lead to a higher rate of birth defects.[44]
Some reasons that men seek vasectomy reversals include wanting a family with a new partner following a relationship break-down/divorce, their original wife/partner dying and subsequently going on to repartner and to want children, the unexpected death of a child, or a long-standing couple changing their minds some time later often by situations such as improved finances or existing children approaching the age of school or leaving home.[46] Patients often comment that they never anticipated the possibility of a relationship break-down or death (of their partner or child), or how that may affect their situation at the time of having their vasectomy. A small number of vasectomy reversals are also performed in attempts to relieve postvasectomy pain syndrome.
In order to allow the possibility of reproduction via artificial insemination after vasectomy, some men opt for cryostorage of sperm before sterilization.
It is advised that all men having a vasectomy consider freezing some sperm before the procedure. Dr Allan Pacey (senior lecturer in andrology at Sheffield University and secretary of the British Fertility Society) notes that men who he sees for a vasectomy reversal which has not worked, express wishing they knew they could have stored sperm. Pacey notes, "The problem is you're asking a man to foresee a future where he might not necessarily be with his current partner - and that may be quite hard to do when she's sitting next to you."[46]
The cost of Cryo-preservation (Sperm Banking) itself may also be substantially less (approximately every five years) than alternative Vaso-vasectomy procedure(s), (est surgery cost of ); however the costs of In-vitro fertilization which are rarely below US, and usually run between –15,000 U.S., must be considered.[citation needed]
Intracytoplasmic sperm injection: Sperm can be aspirated from the testicles or the epididymis, and while there is not enough for successful artificial insemination, there is enough to fertilize an ovum by I.C.S.I. This avoids the problem of anti-sperm antibodies and may result in a faster pregnancy. IVF (In-vitro fertilization) may be less costly (see aforementioned text) per cycle than reversal in some health-care systems, but a single I.V.F. cycle is often insufficient for conception. Disadvantages include the need for procedures on the woman, and the standard potential side-effects of I.V.F. for both the mother and the child.[47]
This section may be unbalanced towards certain viewpoints. Please improve the article by adding information on neglected viewpoints, or discuss the issue on the talk page. (November 2013) |
In the mid-1970s, surveys were used to examine the effects of vasectomy in relation to postoperative sexual behaviour, satisfaction and happiness, with generally positive answers in their "ticked boxes". However, a different picture emerges from psychology-based clinical interviews and tests, employing more rigorous methodology and measurement techniques. Although men in general verbally expressed satisfaction with their vasectomy, the authors of one review reflected "many men were probably describing feelings which have been distorted as part of an attempt to cope with their private concerns about the consequences of the operation".[48] In addition, many men experienced difficulty in adjusting to the psychological consequences of vasectomy.[48]
These differing results between simple surveys and more elaborate interviews and psychological reviews, are revealing of some of the difficulties in trying to measure the psychological impact of vasectomy on men.
Most surveys following vasectomy show sexual desire and satisfaction levels remaining at the same level or greater (without the risk of pregnancy), and generally most men being content with their decision to have a vasectomy.[49] Approximately 90% are generally reported in reviews as being satisfied with having had a vasectomy,[50] while between 7-10% of men regret their decision.[51] Most surveys frame questions as to "satisfied" or "not satisfied", and do not provide for ambiguous, ambivalent or complex emotions, which may exist along-side "overall satisfaction" with vasectomy.
One of the strongest contraindications to vasectomy, in psychological terms, is disagreement with one's wife or feeling "bullied into" a vasectomy, with men reporting this situation as experienced the highest level of negativity and regret subsequent to having a vasectomy.[52]
The psychological effects of vasectomy may also continue or resurface throughout a man's life, beyond the period of a survey's scope. While a man may initially be satisfied with his decision to have a vasectomy, this view may change later on in life, such as subsequent to the break-down of his primary romantic relationship and recoupling with a new partner who desires children. This situation of repartnering later in life has led to what has been characterised as a boom in vasectomy reversals and regrets in which, although the man was happy with his decision at the time of getting the vasectomy, he subsequently regretted the decision later on in his life.[46] Altered situations including death of a partner, relationship break-down, children starting school or leaving home, death of a child, repartnering and remarriage, increased wealth (which previously factored against having more children), mean that the psychological associations and effects of vasectomy are not only those which immediately follow the vasectomy, but may continue throughout a person's life.[46][53] It is acknowledged that around 5% of men go on to have a vasectomy reversal, and a much higher portion enquire about or seek a vasectomy reversal but are put off by the high costs of surgery and its interplay with the only moderate to moderately low success rates.[53] (See Vasectomy reversal). Men who are of a younger age at the time of having a vasectomy are significantly more likely to regret and seek a reversal of their vasectomy, with one study showing men for example in their twenties being 12.5 times more likely to undergo a vasectomy reversal later in life (and including some who chose sterilization at a young age),[54] promoting a greater level of prevasectomy counseling as being required.
An area not yet subject to adequate study is the psychological impact of conflict and disharmony with his wife or partner over his hesitance towards vasectomy or decision not to undergo a vasectomy. Or vice versa, in situations where it is the man who wants the vasectomy and his partner who is against it, has similarly not been subject to part of survey results in terms of psychological impact.
In relation to masculine identity, some early research suggested that men who have undergone vasectomy adopt more stereotypically masculine behaviors as compensatory for a diminished sense of masculinity, which is opposed by the research of Amor et al. who found that vasectomy often enhanced their sense of masculinity (among their study of nineteen men).[55]
Egalitarian approaches seek to decrease levels of inequality in the "contraceptive burden" which exist between males and females, with implications for the topic of vasectomy. The corresponding female surgical sterilization procedure known as Tubal ligation is considered a major surgery usually done with general anesthesia (or with an epidural while giving birth), typically done at an in-patient, hospital setting. This argument falls apart with modern techniques such as Sterilization by Laparoscopy which has shorter or similar recovery times than vasectomy.
The emphasis on "shared responsibility" has been taken up in recent research and articles by Terry and Braun, who regard much of the earlier psychological research on vasectomy as seemingly negative, or 'suspicious' in tone.[56] In research based on 16 New Zealand men (chosen for their enthusiasm on the topic of vasectomy), researchers extracted primary themes from their interviews of "taking responsibility" and "vasectomy as an act of minor heroism’.[57]
The need to "target men’s involvement in reproductive and contraceptive practices" was historically raised on a global scale at the 1994 International Conference on Population and Development (ICPD) in Cairo,[58] in relation to both population control and decreasing the levels of inequality in the ‘contraceptive burden’, which has traditionally placed responsibility for contraception unfairly upon women. Vigoya has referred to a global "cultura anticonceptiva femenina" - a female contraceptive culture, where, despite the possibility of men taking more responsibility for contraception, there is virtually nowhere in the world where true contraceptive equality exists.[59]
Feministic researchers emphasize the positive identities that men can take up postvasectomy, as a "man who takes on responsibility for the contraceptive task"[57] and a man who is willing to "sacrifice" his fertility for his partner and family's sake.[56] Often these sorts of accounts are constructed within the 'contraceptive economy' of a relationship, in which women have maintained responsibility of the contraceptive task up until the point of the operation. Terry notes that a man undergoing a vasectomy may also mean he receives a high degree of gratitude and positive reinforcement for making the choice to be sterilised, perhaps more so than a woman who has been on an oral contraceptive or similar for years prior.[57]
An alternative view-point of contextualizing vasectomy debate is the evolutionary "battle of the sexes" conflict of interest. From a Darwinian stand-point, males may increase their genetic fitness by mating with multiple women over the course of their lives (see Sexual Conflict). As a woman's reproductive capacity reduces significantly with age towards menopause, eventually ceasing while a male partner is still able to reproduce (see Age and Female Fertility), she benefits in evolutionary terms from her partner undergoing vasectomy - eliminating or greatly restricting his ability to mate with other women in the future, thus helping to ensure or protect her partner's investment and resources for herself and any progeny. Vasectomy may in this way be advantageous to female reproductive strategy (after a threshold number of children are born), and detrimental to the male reproductive strategy, if viewed in generalized evolutionary fitness terms alone.
Vasectomy is the most effective permanent form of contraception available to men. In nearly every way that vasectomy can be compared to tubal ligation[60] it has a more positive outlook. Vasectomy is more cost effective, less invasive, has techniques that are emerging that may facilitate easier reversal, and has a much lower risk of postoperative complications. Despite this, in the United States, vasectomy is utilized at less than half the rate of the alternative female "tubal ligation".[61] According to the research, vasectomy is least utilized among black and Latin populations, the U.S. groups that have the highest rates of female sterilization.[61]
New Zealand, in contrast to the U.S., has higher levels of vasectomy than tubal ligation uptake. 18% of all men, and 25% of all married men have had a vasectomy. The age cohort with the highest level of vasectomy was 40-49 where 57% of men had taken it up.[62] Canada, the UK, Bhutan and the Netherlands all have similar levels of uptake.[63]
Medical tourism, where a patient travels to a less developed location where a procedure is cheaper to save money and combine convalescence with a vacation, is infrequently used for vasectomy due to its low cost, but is more likely to be used for vasectomy reversal. Many overseas hospitals list vasectomy as one of their qualified surgical procedures. Medical tourism has come under the scrutiny of some governments for quality of care and postoperative care issues.[64]
The first recorded vasectomy was performed on a dog in 1823.[65] A short time after that, R. Harrison of London performed the first human vasectomy; however the surgery was not done for sterilization purposes, but to bring about atrophy of the prostate. Soon, however, it was believed to have benefits for eugenics. The first case report of vasectomy in the U.S. was in 1897, by A. J. Ochsner, a surgeon in Chicago, in a paper titled, "Surgical treatment of habitual criminals." He believed vasectomy to be a simple, effective means for stemming the tide of racial degeneration widely believed to be occurring. In 1902, Harry C. Sharp, the surgeon at the Indiana Reformatory, reported that he had sterilized 42 inmates, in an effort to both reduce criminal behavior in those individuals and prevent the birth of future criminals.[66] Vasectomy began to be regarded as a method of birth control during the Second World War. The first vasectomy program on a national scale was launched in 1954 in India.
Vasectomy costs are (or may be) covered in different countries, as a method of both contraception or population control, with some offering it as a part of a national health insurance. The Affordable Care Act of the U.S. does not cover vasectomy. Vasectomy was generally considered illegal in France until 2001, due to provisions in the Napoleonic Code forbidding "self-mutilation". No French law specifically mentioned vasectomy until a 2001 law on contraception and foeticide permitted the procedure.[67]
Sharia (Islamic law) traditionally does not permit permanent sterilization.[citation needed] However, on July 2, 2012, the Indonesian Ulema Council agreed to permit vasectomies in Indonesia subject to certain requirements, including:[68]
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リンク元 | 「精管結紮術」 |
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