During male sterilization (vasectomy), the two vas deferens are cut in the scrotum and the loose ends are then closed off. This means that sperm can no longer enter the seminal fluid.
The procedure

Vasectomy is usually performed as an outpatient procedure under local anesthesia or under general anesthesia in a urologist’s office. The procedure takes about half an hour in total.
There are several surgical procedures available for cutting the two vas deferens in the scrotum. In vasectomy "without scalpel", the scrotum skin and the spermatic cord sheaths are only incised and spread to gain access to the spermatic ducts. This procedure is associated with comparatively minor surgery-related complications such as bruising (hematoma). Wound infections also occur comparatively rarely.
The two vas deferens are pulled out a bit through the small hole that is created and then severed. Afterwards, the loose ends of the vas deferens are closed by ligation, heat, chemical substances or with titanium clips and relocated to different tissue layers of the scrotum so that they do not grow together again. Usually no skin sutures are necessary, so that at the end two small plasters on the scrotum skin are sufficient.
In other techniques, incisions are made to access the vas deferens. In addition, the vas deferens are not only cut, but also shortened by about one centimeter each.
In terms of contraceptive safety, none of the methods has so far proven to be better. Regardless of the surgical technique used, a few days of physical rest and sexual abstinence are usually enough to recover after the procedure. If possible, you should refrain from sports and physical training for two weeks. Sometimes it is also recommended to wear a testicle protector (jockstrap) during this time.
The procedure does not affect the production of hormones and sperm in the testicles. Since the vas deferens are cut, the sperm no longer reach the seminal fluid (ejaculate) and are broken down by the body. The process of degradation happens unnoticed and painless. A vasectomy is not to be confused with castration, in which the testicles are surgically removed or their function is hormonally suppressed.
The sterilization of the male

Small incisions are made on the left and right sides of the scrotal skin or the scrotal skin is scored and spread to expose the two vas deferens.

The two vas deferens are cut or clamped off.
Follow-up
To check if there are still fertilizable sperm in the ejaculate, the seminal fluid should possibly be examined several times after the procedure. It may take several months before you are safely infertile, as there is still a lot of sperm in the upper sections of the vas deferens even after vasectomy. It usually takes 15 to 20 ejaculations before there are no more sperm to be found. Only when sperm are no longer present can you dispense with further contraceptives. The follow-up check of the seminal fluid is also important to check whether the severed vas deferens may have grown together again.
Safety
Vasectomy is the most reliable contraceptive method for men. The failure rate with perfect application is 0.1 percent, with typical application 0.15 percent.
It happens that the severed vas deferens grow together again by themselves in the first months after the vasectomy (recanalization). Data on how often it happens varies from 50 to 530 out of 10.000 cases. It is therefore important that the success of the procedure is ensured by one or two follow-up checks. Until successful follow-up, additional contraception is required.
In very rare cases (estimates range from 3 to as many as 120 out of 10.000) recanalization may occur years after the operation, which may lead to pregnancy.
Advantages
The advantage of a professionally performed vasectomy is its high safety as a contraceptive method. Vasectomy has no direct effect on sexual pleasure, penile erection, orgasm and ejaculation. Also, the amount of seminal fluid in a sterilized man is little different from that of a non-sterilized man, as sperm make up only about five percent of the ejaculate.
Vasectomy is also a comparatively simple surgical procedure, during which complications rarely occur. Female sterilization (tubal sterilization), in which the fallopian tubes are cut during abdominal surgery, is more complex and involves significantly higher surgical risks.
Possible complications
Complications after vasectomy are rare overall. It also depends on the surgeon’s experience how the procedure goes. It is therefore advisable to have the operation performed in a practice or clinic that performs more than fifty vasectomies a year.
In the days following the operation, one to two percent of men experience symptoms such as bruising, feelings of pressure in the testicles, wound infections or inflammation of the epididymis. With appropriate treatment, they generally disappear again soon.
A few months after the procedure or even later, small nodular tissue inclusions of sperm cells may form (sperm granulomas). They are usually a result of pressure in the testicles caused by the sperm that continue to be produced. Normally they remain unnoticed, but in individual cases they can contribute to a fusion of one of the vas deferens (recanalization).
In addition to unexpected psychological problems with infertility, chronic pain in the testicular area is also among the possible late effects of a vasectomy. In some cases, they intensify during sexual activity and, in rare cases, can considerably reduce the quality of life. How often this so-called post-vasectomy pain syndrome occurs has not yet been adequately researched. The number of men who seek medical treatment for this varies between one and 14 percent.
The causes of the pain are not yet precisely known. There are many indications that the pressure compensation in the testicles does not function adequately in the affected men. In addition, nerves may have been damaged during the operation. Under certain circumstances, another operation may be necessary – for example, a specific recanalization, the removal of the epididymis or the spermatic cord nerves.
Men with a previous groin operation, with pre-existing problems in the lumbar spine area and/or occasional pulling in the testicle area should be sure to mention this in the consultation prior to a vasectomy. This is also true for all other types of chronic pain.
A number of studies have investigated whether there might be a link between vasectomy and prostate cancer. A current summary of the study situation comes however to the conclusion that here no reason for the concern exists. It is highly unlikely that a vasectomy is responsible for later prostate cancer.
Well-considered decision
Sterilization is a very safe method of contraception, because it leads to permanent infertility. The step should therefore be well-considered and should only be considered when you are sure that you do not want to have any (more) children. What is valid at the moment can quickly change under other life circumstances. It happens again and again that with a new partnership also the desire for a (further) child grows.
Although advances in microsurgery make it possible to reverse sterilization in principle (refertilization). But the procedure is not only time-consuming and relatively expensive. There is also no certainty that this will actually restore fertility.
The risk of regretting the sterilization later is greater the earlier in life the procedure is performed. Also in difficult life situations, for example after a separation or divorce, after an abortion or due to an unwanted paternity, it is more common to make wrong decisions. Especially in such crisis phases it is important to take your time and not to act hastily.
You and your partner should agree that you do not want to have children (any more) and consider together what effects the step might have on your relationship – also in sexual terms. This also applies to men and women who are not in a committed relationship. No one should be pressured into a sterilization, not even by the partner. Ultimately, each man must decide for himself whether this is the right step to take.
Can the procedure be reversed?
Microsurgical procedures make it possible in most cases to reconnect severed vas deferens. However, this does not mean in every case that the man is then fertile again. Often sperm production has deteriorated in the meantime for various reasons. The so-called refertilization is also a comparatively complex operation: it takes about two hours and requires general anesthesia.
It is possible to have one or more sperm samples frozen (for a fee) before a vasectomy (cryopreservation). However, the procedure is usually only offered to male cancer patients who wish to have children before chemotherapy or radiation treatment. A healthy man considering cryopreservation of his sperm before a vasectomy is more likely to be advised to check whether his decision is really mature.
According to the German Society of Urology (DGU), a vasectomy is not recommended if the man does not have a committed relationship and does not yet have children, is not yet 30 years old, or if he has chronic pain in the testicular area or a severe general illness. Also, he should not be in a mental crisis.
Costs
A vasectomy, which a man decides to have for non-medical reasons, has to be paid by himself. It costs between 450 and 500 euros, depending on the practice. It is advisable to ask in advance whether all necessary check-ups are included in the price.