Vasectomy is now well recognized worldwide as one of the safest and most effective contraceptive methods. It is estimated that more than 42 million men are currently vasectomized.¹ Although most are concentrated in a small number of countries, the distribution of users is becoming increasingly widespread. In comparison, an estimated 150 million women have been sterilized worldwide; however, in several countries, vasectomy incidence approaches that of female sterilization. In 1995, an estimated 494,000 vasectomies were performed in the United States, for a rate of 9.9 procedures per 1000 men aged 25 to 49 years,² compared with 693,000 tubal sterilizations, for a rate of 11.7 per 1000 women aged 20 to 49 years.³

Some predicted that men would not accept the vasectomy procedure because they fear loss of masculinity or because they mistakenly equate vasectomy with castration. However, when vasectomy is properly presented, men in all societies can welcome the procedure. Several conditions appear to be of critical importance. Men's desire to limit family size and their concern for economic and educational advancement must outweigh their desire for more children, and their concerns about maternal morbidity and the failure of female contraceptive methods must be an overriding consideration.

Most couples seeking vasectomy are dissatisfied users of other forms of contraception. Many couples find barrier methods inconvenient. Women using hormonal methods may have suffered from related side-effects or experienced user difficulties such as limited access to pill supplies or trained providers for implants. Intra-uterine devices also have associated side-effects.

As is true with many other contraceptive methods in which popularity and acceptance preceded thorough scientific understanding of effects on body systems and long-term sequelae, the effects of vasectomy have come under scrutiny by investigators. In the past 20 years, immunologic response and effects on lipid metabolism, spermatogenesis, epididymal function, and hormone levels have been studied. Long-term complications following vasectomy, including increased risk for heart disease, testicular cancer, immune complex disorders, and a host of other conditions, have not been supported by long-term, well-designed epidemiologic studies. The relation between vasectomy and prostate cancer has been studied intensely and, taken as a whole, these studies provide little evidence for a causal association between vasectomy and prostate cancer.

The clinical use of vasectomy is historically linked with the course of experimental investigation. The first reference to the occluded vas was made by Hunter during his dissections in 1775. The first experiment in tying of the vas was reported as early as 1785, but it was not until the 19th century that several investigations into the effects of vasectomy were undertaken. In 1830, Cooper initiated the first systematic experimental work when he demonstrated that closing the duct of the testis had no effect on the production of sperm by the testis for as long as 6 years after the operation. In 1921, Simmonds noted that even in cases in which the vasa deferentia had been occluded for many years, there was no apparent injury to the sperm-producing functions of the testicles. Gosselin confirmed this finding in 1947.

In the late 1890s, an investigation of the clinical uses of vasectomy was begun by surgeons in conjunction with therapeutic operations on the prostate gland. Ochsner performed such operations and reported that no change was noted in the sexual function of his patients following successful vasectomies.

In the 1920s, Rolnick studied the regenerative power of the vas and its ability to resist trauma and restore continuity of its lumen. He emphasized the importance of the blood supply and the sheath of the vas acting as a splint making a path of epithelialization during recanalization and after vas ligation. This classic work still has pertinence today in our efforts to achieve successful vas occlusion and to reduce the chance of failure, and informs us about the potential for successful vasectomy reversal when indicated.

The male reproductive organs include the testicles, the ducts, and the accessory glands (Fig. 1). The testicles produce sperm and the male sex hormone testosterone. After vasectomy, the testes continue to produce both sperm and hormones.

The second group of organs is a series of connected ducts: the epididymides, the vasa deferentia, and the urethra. Each of the two epididymides (which begin at and are connected to the testes) are connected to one of the vasa deferentia. Sperm pass through the epididymis to get from the testis to the vas and are also stored in the most distal portion, or tail, of the epididymis. Sperm become motile and acquire the ability to fertilize ova during transport through the epididymides. The vasa begin at the epididymides and end at the base of the prostate, where they come together and are connected to the urethra and the accessory glands. Here, the sperm, which were carried by the vasa deferentia, mix with secretions from the accessory glands. The urethra carries the semen (i.e. sperm contained in the secretions from the accessory glands) out of the body during ejaculation. The urethra also carries urine.

The third group of internal organs are the accessory glands. These include the seminal vesicles, the prostate, and the bulbourethral glands. These glands secrete the seminal fluid that carries sperm through the urethra during ejaculation.

The vas deferens is a firm, tubular structure approximately 3 to 4 mm in diameter and approximately 35 cm in length. It extends from the tail of the epididymis to the prostate, where, together with the duct of the seminal vesicle, it forms the ejaculatory duct.

The vas deferens may be divided into five portions: the sheathless epididymal vas, the scrotal vas, the inguinal vas, the retroperitoneal or pelvic vas, and the ampulla (Fig. 2). The portion of the vas of clinical interest in relation to vasectomy is the scrotal vas in the midscrotal area. Here the vas is located within the spermatic cord, which is made up of fascia, arteries, veins, and nerves and which suspends the testis in the scrotum (Fig. 3). The firm, thick structure of the vas can be easily palpated and differentiated from other structures in the spermatic cord. Also in the spermatic cord is the testicular artery, which supplies blood to the testis and epididymis, and the testicular veins, which form the pampiniform plexus that returns blood from the testis and epididymis.

The vas deferens is composed of three layers of smooth muscle: the outer and inner longitudinal layers and the middle circular layer. It is capable of powerful peristaltic motion. There is a thick sheet of connective tissue exterior to the muscle layer. The lumen of the vas, like that of the epididymis, is lined with pseudostratified epithelium and contains longitudinal folds lined with microvilli.

The blood supply of the vas deferens is from the artery of the vas deferens (deferential artery), a branch of the superior vesical artery that is also important in collateral circulation for the testicle. This artery is easily separated from the vas during vasectomy; however, it may be a source of hemorrhage during vasectomy if it is not separated or ligated.

The nerves of the testes (the superior spermatic nerves) arise from the renal plexus and intermesenteric nerves and travel in association with the testicular arteries, whereas the inferior spermatic nerves arise from the hypogastric plexus and course around and along the vas deferens to innervate the epididymides. At the junction of the epididymis and vas deferens, the amount of adrenergic innervation increases, with innervation of the vas consisting of short, postganglionic neurons.⁴ Adrenergic fibers, which are found in all three smooth muscle layers, are most likely the motor supply of the vas muscle. The sheath of the vas in the scrotal portion contains pain nerves. Careful infiltration of the sheath with local anesthetic agents is effective in reducing pain during the procedure.

Blood vessels and nerves involved in erection and ejaculation, including the internal pudendal artery, dorsal and cavernous veins, pudendal nerves (sensory nerves to the penis), and nerves from the pelvic plexus arising from sacral nerves S2-S4 (nerves involved in erection), are located well away from the procedure site and are therefore unaffected by vasectomy.

The patient's request for vasectomy must be made voluntarily. Good counseling for men interested in vasectomy is critical for two reasons: vasectomy is permanent, and vasectomy is a surgical procedure that carries with it the risks inherent in any surgery. Because men's greatest fears about vasectomy are related to pain of the procedure, impact on sexual functioning, and potential for adverse effects,⁵ these topics should be thoroughly covered during counseling. Counseling should involve both partners if possible and include the following steps^6,7,8:

1. Discuss vasectomy in conjunction with an explanation of all other available contraceptive options.
   
2. Discuss the patient's readiness to end his fertility and screen for indicators of poststerilization regret. Factors shown to predispose to poststerilization regret include young age (less than 31 years), quick or economically motivated decision or decision related to pregnancy, marital instability, and no children or children very young at the time of sterilization.^9,10,11 The provider should explore with the individual whether he would feel differently if his marital situation changed or if he lost his spouse or a child. Identifying regret risks should not be a reason for denying vasectomy but should be an indicator that more careful counseling and discussion of other contraceptive methods are necessary.
   
3. Emphasize that vasectomy should be regarded as a permanent procedure, and inform the client of failure rates associated with vasectomy. Despite what the client may have heard about vasectomy reversal, it is expensive, and success cannot be guaranteed. If a client considering vasectomy is seriously thinking about reversal, a vasectomy may not be the best procedure for him at this time. Likewise, if a man asks to have his sperm stored in a sperm bank for the future, mention to him that this is costly and viable long-term storage is not without risk and that he may want to reconsider vasectomy.
   
4. Using diagrams, briefly describe the vasectomy procedure and how a vasectomy works. Describe to the patient the surgical site, time the procedure usually takes, type of anesthesia, length of recovery, and resumption of sexual activity. Discuss general surgical risks. Emphasize that vasectomy is not effective immediately and that the client should use an alternate method of contraception until his semen is tested and found to be free of sperm.
   
5. Describe all medical benefits and risks. Fears and myths regarding the long-term health effects of vasectomy often lead to eventual dissatisfaction with the procedure. Although the body of research suggests that vasectomized men are no more likely than nonvasectomized men to develop heart disease and cancer, preventive lifestyle and screening should be addressed. Emphasize that vasectomy provides no protection against sexually transmitted diseases, including human immunodeficiency virus (HIV) infection.
   
6. Point out that vasectomy does not cause a loss in physical strength, development of a high pitched voice, a loss or change in sexual function, weight gain, or a loss of masculinity. Inform the client that he will still ejaculate after surgery and in the same amount. The semen will not, however, contain any sperm after successful vasectomy. Some studies have indicated that sexuality may improve because couples do not worry about accidental pregnancy.
   
7. Tell the patient about any fees he is expected to pay. Ensure compliance with local, state, and institutional restrictions regarding age, waiting periods, and second opinions.
   

Throughout the discussion, answer client questions and concerns. Use diagrams and pictures of instruments to reduce patient anxiety. Emphasize that vasectomy is a safe, moderately priced, simple, and highly effective procedure.

Provide printed educational materials that the client and his partner can review privately, as well as oral and written preoperative instructions. Preoperative vasectomy patients must avoid aspirincontaining drugs for 2 weeks before and 1 week after surgery.⁸ The client must also undergo a limited physical examination; in specific cases, laboratory workup is required (blood count, bleeding and clotting time, urinalysis, and semen analysis), but this is not routinely done. On the day of surgery, the client should bathe or shower and wear loose-fitting clothing. If necessary, hair on the scrotum should be clipped immediately before the procedure and not by the client at home. The client should bring an athletic supporter or briefs to wear after the surgery.

The client signs an informed consent form on the day of surgery to indicate that he has reviewed the information given him and discussed his decision with the vasectomy provider. The client must understand the six points of informed consent listed below and know what he is signing. The provider should encourage the client to ask questions. The six points of informed consent are¹²:

1. Temporary contraceptive methods are available to the client and his partner.
   
2. Vasectomy is a surgical procedure.
   
3. There are certain risks associated with vasectomy, as well as benefits, both of which must be explained.
   
4. If successful, vasectomy will prevent the client from having any more children.
   
5. The effect of vasectomy is to be considered permanent.
   
6. The client can decide against the operation at any time before the procedure without losing the right to other medical, health, or other services or benefits.
   

With a witness present, the client's signature or mark should be obtained. If the client is illiterate, the provider should obtain a witness's signature attesting that the client has affixed his mark or thumbprint on the informed consent form.

There should be no rigid guidelines concerning waiting periods between the prevasectomy medical history and physical examination and the performance of the vasectomy. Generally, a 2- to 3-week period gives the client or couple sufficient time to consider any possible concerns about effects on sexuality or health. Table 1 lists the required and recommended components of a prevasectomy medical history and physical examination and explains the reason each component is included.

TABLE 1. Components of a Prevasectomy Medical History and Physical Examination

After the client's heart, lungs, and abdomen have been examined, a genital examination should be performed. Before beginning the examination, the surgeon should tell the client what will be done and why it is done. The man is assured that he will feel minimal pain. During the genital examination, penile and scrotal examination is conducted. Unless lesions are observed, gloves are unnecessary during a genital examination, but the doctor should wash his or her hands thoroughly before and after the examination.

Visual Inspection

The penis is visually inspected, and any lesions or scarring are noted. The penis, including the underside, is gently lifted and examined. The urethral opening is examined. Any abnormalities such as discharge, reddening, or irritation are noted and assessed.

Potential Abnormalities

Potential abnormalities include rash, cyst, discharge, and skin cancer (rare).

Visual Inspection

The scrotal skin is visually inspected. The scrotum is lifted to examine the posterior side. Coloring, size, and contour are observed. Any swelling or masses are noted and assessed.

Potential Abnormalities

Potential abnormalities include rash, cysts, poorly developed scrotum (possible cryptorchidism), and swelling (possible inguinal hernia, torsion of spermatic cord, strangulated inguinal hernia).

Using the thumb and first two fingers, the doctor palpates each testis and epididymis (Fig. 4). He or she avoids putting pressure on the testis during the palpation so as not to cause pain. The size, shape, and consistency of each testis and epididymis are noted. Any nodules or tenderness are noted.

Potential Abnormalities

Painless nodules in the testes may indicate testicular cancer. Nodules in the epididymis may indicate an epididymal cyst (seminoma).

Each spermatic cord and its vas deferens are palpated (Fig. 5). The doctor moves his or her thumb and fingers along its length. Any nodules or swellings are noted.

Potential Abnormalities

Potential abnormalities include thickened vas (suggests chronic infection), tortuous veins (suggests varicocele), and cyst in the cord (suggests hydrocele).

Although vasectomy is a simple operation that can be performed almost anywhere, the more removed the setting is from medical back-up, the more important it is to screen out men who are likely to develop complications.

The major physical precautions to performing vasectomy are local skin infection and systemic blood disorder. Local skin infection, which can prevent normal healing or increase risk of postoperative infections, is easily recognized and should be treated and the condition resolved before the operation is performed. Other local conditions that make vasectomy more difficult to perform include inguinal hernia, previous surgery for hernia or orchiopexy, hydrocele, varicocele, preexisting scrotal lesions, and a thick, tough scrotum.

Systemic blood disorders that call for special precautions include any disease that interferes with normal blood clotting (e.g. hemophilia). In such cases, the vasectomy technique used should minimize tissue trauma, and emergency equipment should be available. If the patient is taking anticoagulants, the same precautions may be required. Other systemic diseases, such as diabetes, hypertension, or other cardiac disease, are not contraindications to vasectomy, but hospitalization and intraoperative monitoring with prolonged close observation and follow-up are advisable in case emergencies arise. Table 2 presents the World Health Organization's eligibility criteria for vasectomy procedures,¹³ which include standard vasectomy precautions.

TABLE 2. WHO Eligibility Criteria for Vasectomy Procedures

Just prior to surgery, the surgeon should verify that the patient has signed an informed consent form. The guide presented in Figure 6 can be used in making a final assessment of the patient's informed decision to have a vasectomy.

Approaches to the Vas

Conventional vasectomy is performed under local anesthesia. A scalpel is used to make either one midline incision or two incisions overlying each vas deferens; these incision or incisions are 1 to 2 cm long (Fig. 7). After occlusion of the vasa using the surgeon's preferred technique, the incision or incisions are closed with sutures.

No-scalpel vasectomy is a method of delivering the vasa deferentia under local anesthesia that was developed and has been used in China since 1974.^14,15 It has been introduced in many developed and developing countries. This technique eliminates the need for use of a scalpel and instead utilizes two specialized instruments: a ringed clamp (Fig. 8) and dissecting forceps (Fig. 9). No-scalpel vasectomy involves a deep injection of local anesthetic applied alongside each vas, creating a vasal nerve block (Fig. 10). In conventional vasectomy techniques, only the area around the skin entry site is anesthetized.

The ringed clamp encircles and firmly secures the vas without penetrating the skin (Fig. 11). A sharp, curved hemostat (the dissecting forceps) punctures and spreads the scrotal skin and vas sheath. The vas is delivered, cleaned, and occluded using the surgeon's preferred technique (Fig. 12). The contralateral vas is then delivered through the same opening and occluded. The puncture wound contracts to about 2 mm, is not visible to the client, and requires no sutures for closure.

No-scalpel vasectomy offers several advantages over conventional vasectomy. No-scalpel vasectomy results in fewer hematomas and infections compared with conventional vasectomy (Table 3).

TABLE 3. Incidence of Infection and Hematoma or Bleeding After Vasectomy

In a 1991 survey conducted in the United States, 78 out of 111 surgeons (70%) said they believed patients undergoing no-scalpel vasectomy with vasal block anesthesia experienced less operative pain than did patients undergoing conventional vasectomy.¹⁵ Indeed, men undergoing no-scalpel vasectomy reported less pain during the procedure and early follow-up period, and also reported earlier resumption of sexual activity after surgery.^20,22 Because there is no scrotal incision, no-scalpel vasectomy is believed to decrease men's fears regarding vasectomy.¹⁵

Neither conventional nor no-scalpel vasectomy is time consuming; however, there are reports of decreased operating time when skilled providers use the no-scalpel approach. For example, a study in Thailand showed that surgeons who used the no-scalpel technique were able to perform an average of 57 procedures per day, whereas those using the conventional technique performed an average of 33 procedures per day.¹⁸ Similarly, in the United States, a 40% reduction in operating time has been reported with no-scalpel vasectomy.¹⁴

Occlusion of the Vas Deferens

A variety of methods are currently used for occlusion of the vas, including ligation with sutures, division, cautery, clips, excision of a segment of the vas, and combinations thereof. Simple ligation without division and simple division alone are not recommended, because the potential for failure due to recanalization is high. There is little consensus regarding what occlusion technique is best. In the United States, for example, results of a recent survey indicated that occlusion technique varied: 38% of vasectomies were performed using ligation and cautery, 18% using ligation only, 18% using cautery only, 15% using cautery and clips, 9% using clips only, and 2% using ligation and clips.²

This lack of consensus is partially due to the fact that good research data are unavailable to support the use of any one technique over another. Most reports in the literature are retrospective reviews of individual physicians' experiences of either a single occlusion method or sequential use of two methods. It is difficult to interpret some studies because details on definitions of failure, follow-up protocols, loss to follow-up rates, or statistical methods are often lacking. Although these factors also contribute to the difficulty in comparing results among studies, the fact that most studies use a different occlusion technique—ligation, clips, cautery, excision versus no excision, closed versus open, fascial interposition versus no fascial interposition, or different combinations of the various technique— makes most comparisons across studies questionable. Often, however, individual surgeons have their own preferences regarding occlusion method.

Similarly, there is little information on the relation of the length of vas removed and the success of the procedure. Hallan and May²³ determined that 7 cm of vas had to be removed to alleviate the possibility of a sperm granuloma bridging the gap between the cut ends of the vas. Although most surgeons remove a segment of the vas, some investigators report success using division and occlusion of the vas without removal of any vas tissue itself.^8,24–26

Routine referral of the vas for pathologic study is neither essential nor recommended. The presence of two vas specimens does not substitute for determining the endpoint of azoospermia. Because the same vas may have been sectioned twice or a double vas may be present, the patient may still be fertile despite the fact that two separate specimens have been sent to the laboratory. Conversely, even if the laboratory cannot confirm the presence of vasa on microscopic examination, the patient may still have a successful procedure, because tissue can be distorted in removal or lost in transit to the laboratory.

Open-ended vasectomy (i.e. not sealing the testicular end of the cut vas) has been examined as a way of increasing the likelihood of success if subsequent reversal is requested. There is some evidence that open-ended vasectomy leads to reduced pressure-induced damage of the epididymis.²⁷ Published studies vary; some report low failure rates comparable to those usually reported for closed-ended vasectomy techniques,^26,28,29 and others report higher failure rates with the open-ended technique.^30,31,32 Open-ended vasectomy is not commonly practiced.

Fascial interposition, or suturing the spermatic fascia over one end of the vas to place a tissue barrier between the two cut ends, has been theorized as a way to reduce the potential for recanalization. Although some investigators have reported good results with this technique,^24,33,34 others have reported low and comparable failure rates when fascial interposition is not used.^16,35 Results from randomized clinical trials comparing no fascial interposition with fascial interposition have not been reported. In the United States, 48% of physicians reported they use fascial interposition when performing vasectomies.²

Men who have undergone vasectomy may leave the health facility after resting for 30 minutes. If the patient has been sedated, his vital signs should be monitored every 15 minutes until stable; he then can be released. Information should be provided in simple language to the patient regarding how to care for the wound, what side effects to expect, what to do if complications occur, where to go or who to call for emergency care, and where and when to return for a follow-up visit. The patient should be informed that minor pain and bruising are common and do not require medical attention. However, if he develops a fever, if blood or pus oozes from the vasectomy site, or if excessive pain, swelling, or bruising occurs, he should seek medical care. Written postvasectomy instructions should be provided (Fig. 13).

Vasectomy success is routinely confirmed by demonstrating the absence of sperm (i.e. azoospermia) in semen samples obtained at one or more clinic visits following the procedure. The time interval to the first follow-up visit is often between 6 and 12 weeks but may be as great as 4 months postvasectomy. Some clinics schedule follow-up based on the number of ejaculations following vasectomy, which may range from 15 to as many as 30 ejaculations prior to obtaining the first follow-up semen analysis.^2,41,43,44

There is little consistency in follow-up protocols in terms of when men are told to come for the first semen analysis or the number of azoospermic samples required before clearance is given. Of urologists surveyed in one region of the United States, 85% suggested men return for semen analysis based on time since vasectomy, whereas the remaining 15% based the recommendation on number of ejaculations following vasectomy. Fifteen percent reported that they suggest men return for their first semen analysis at less than 5 weeks postvasectomy, 37% said between 6 and 8 weeks, 33% said after 8 weeks, 5% said after 6 to 10 ejaculations, and 10% said after 11 to 20 ejaculations.⁴⁵ More recently, a U.S.-wide study has confirmed that this variability exists throughout the country.²

Large variability also exists in the number of azoospermic samples required before clearance. One U.S. study reported that 55% of physicians recommended one sample, 41% recommended two samples, and the remaining 4% recommended between 2 and 10 samples.⁴⁵ A study by Haws and colleagues² reported similar variability, with 56% requiring one azoospermic sample, 39% requiring two samples, 5% requiring three samples, and less than 1% requiring four samples.

This large degree of variability in clinical protocols for postvasectomy follow-up reflects the fact that good data regarding time and number of ejaculations to azoospermia following vasectomy are limited. Although there are more than one dozen published studies reporting on semen characteristics postvasectomy, well-designed clinical trials with serial follow-up visits are lacking.

A number of studies have reported the results of time to azoospermia following vasectomy.^46–53 Follow-up protocols and procedures, definitions of azoospermia or success, and the way in which results are reported vary widely in these studies. In addition, in some cases, important study details are lacking in the reports. All of these factors make interpretation or generalization of results and comparisons between studies difficult. Reported rates of azoospermia at 6 months range from 48% to 100%.^{46,47,49,52–56}

Relatively little information has been reported in the literature regarding the influence of the number of ejaculations on reaching azoospermia following vasectomy.^46,52,57 Reported results are conflicting. Marshal and Lyon⁴⁶ reported that after 36 ejaculations, all men were azoospermic; Lee⁵⁷ reported that after 10 ejaculations, 87% of men were azoospermic; and Cortes and colleagues⁵² reported that after 60 ejaculations, 95 out of 100 men had achieved azoospermia. Lee also noted that after seven ejaculations all men had less than 1 × 10⁶ sperm/ml.⁵⁷

Several studies have examined changes in sperm function after vasectomy and found a rapid loss of fertilizing competence and sperm motility.^58–61 Sperm function was examined by the zona-free hamster oocyte sperm penetration assay by two groups. One reported no penetration with sperm from day 3 postvasectomy, and the other reported that penetration rates with sperm from days 3 to 16 postvasectomy were significantly lower than prevasectomy rates.^59,60 Sperm motility was shown to decline rapidly, so that, by days 15 to 19 postvasectomy, all men had 0% sperm motility.^58,61 Sivanesaratnam⁴⁹ reported that at the first postvasectomy visit at 1 month, none of the men had motile sperm. In contrast, Edwards⁵¹ reported that some men had motile sperm for up to 9 weeks postvasectomy, and Cortes and colleagues⁵² found that, although the median time to loss of sperm motility was 3 weeks, the cumulative event rate did not reach its maximum of 90 per 100 men until 15 weeks postvasectomy. Taken together, however, these results suggest that the duration of risk of pregnancy following vasectomy may be considerably shorter than the time necessary to clear all sperm from the reproductive tract.

Many of the current follow-up protocols require that men return for their first semen analysis at long intervals after vasectomy, and during this time an alternative method of contraception must be used. In addition, if azoospermia is not found at the initial visit, additional visits are necessary. Compliance with postvasectomy follow-up has been shown to be poor, with 21% to 45% of men not returning for any follow-up, suggesting that the current follow-up protocols do not work very well.^56,62–65

It is possible that azoospermia may not be the best endpoint for vasectomy, and indeed, achievement of azoospermia may not be necessary. As early as 1979 it was suggested that as long as no motile sperm were present, men could rely on their vasectomy for contraception without risk of pregnancy.⁶⁶ Since then, a number of investigators have suggested alternatives to azoospermia in some cases. Two reports have suggested that “special clearance” should be given in cases in which there are two consecutive counts of less than 10,000 sperm/ml, no motile sperm are present, and it has been at least 7 months since vasectomy.^16,67 Edwards⁵¹ suggested that testing be done at 4 weeks postvasectomy, and if no motile sperm are present at this point, clearance should be given. Others suggest longer intervals from 12 to 18 weeks.^53,68 Data from Chan and coworkers suggest that clearance prior to 18 weeks postvasectomy could lead to missing early recanalizations.⁵³

DeKnijff and coworkers⁶⁸ comment that men with low numbers of nonmotile sperm are at low risk of producing pregnancy. There are now a number of reports indicating that nonmotile sperm remaining after vasectomy are not associated with pregnancy.^{16,50,51,66–69} Suggesting that absence of motile sperm be the endpoint for vasectomy is not unreasonable given the fact that sperm motility is required for penetration of cervical mucus⁷⁰ and for penetration of the oocyte.⁷¹ However, at least in the United States, concerns regarding malpractice in cases in which success has been declared without azoospermia and subsequent pregnancy occurs (even if due to recanalization) are likely to affect follow-up recommendations.

Overall, vasectomy is highly effective and one of the most reliable contraceptive methods available. Failure rates are commonly quoted to be between 0.2% to 0.4%, but failure rates reported in the literature show broader ranges, and rates as high as 3% to 5% have been reported.^30,32,35,72 It is important to recognize the limitations of quoting exact failure rates for vasectomy. There are difficulties in interpreting the published studies on vasectomy efficacy because follow-up has been relatively short-term; most reports in the literature are retrospective reviews of individual physicians' experiences; definitions of failure, length of follow-up, and occlusion methods used vary among studies; and details on follow-up protocols, loss to follow-up rates, or statistical methods are often lacking. Large, welldesigned, long-term studies that describe vasectomy failure rates have not been conducted.

Vasectomy failure may be due to user failure or to failure of the technique itself. User failure occurs when alternate contraception is not used during the period after vasectomy but before all sperm are cleared from the reproductive tract. The most common cause of failure of the vasectomy technique itself is spontaneous recanalization of the vas.⁴⁴ This occurs when a sperm granuloma forms at the site of the vasectomy and links the two cut ends of the vas, creating passageways for sperm.^73,74 Recanalization can occur at anytime after vasectomy and is frequently termed early or late. Early recanalization occurs in the first few months after vasectomy before azoospermia is achieved, when sperm counts begin to rise before they have even fallen to zero. Late recanalization occurs after azoospermia has been demonstrated, when motile sperm reappear in the ejaculate.^16,44 Late recanalizations can occur several years after successful vasectomy and are usually only identified when a pregnancy occurs; the actual rate in a large population has never been accurately determined. Other possible but rare causes of failure include occlusion of the wrong structure during the vasectomy procedure or the presence of an extra vas.⁴⁴

Studies have shown that regret among men is associated with marital instability at the time of vasectomy, young age (younger than 31 years), making the decision to have a vasectomy during a time of financial crisis or related to pregnancy, and having very young or no children at the time of vasectomy.^9,10,11,75 Regret is also often the result of client dissatisfaction with adverse health effects caused by or perceived to be caused by the procedure. Risk factors for regret should not be used by providers to restrict access to vasectomy for those in risk groups but rather should be used to identify individuals who may need more extensive counseling. Satisfaction with presterilization counseling has been found to correlate positively with poststerilization satisfaction.^6,76

1. Ross JA, Frankenberg E: Findings from Two Decades of Family Planning Research, pp. 57–62. New York, Population Council, 1993.

2. Haws JM, Morgan GT, Pollack AE et al: Clinical aspects of vasectomies performed in the United States in 1995. Urology 52: 685, 1998.

3. U.S. Centers for Disease Control and Prevention and AVSC International, unpublished data, 1995.

4. Baumgarten HG, Owman C, Sjoberg NO: Neural mechanisms in male fertility. In Sciarra JJ, Markland C, Speidel JJ (eds): Control of Male Fertility, pp. 26–40. Hagerstown, MD, Harper & Row, 1975.

5. Mumford SD: Vasectomy: The Decision-Making Process. San Francisco, San Francisco Press, 1977.

6. Pollack AE, Carignan C, Pati S: What's new with male sterilization: An update. Contemp Ob/Gyn 43: 41, 1998.

7. Haws JM, Butta PG, Girvin S: A comprehensive and efficient process for counseling patients desiring sterilization. Nurse Pract 22: 52, 1997.

8. Davis LE, Stockton MD: No-scalpel vasectomy. Prim Care 24: 433, 1997.

9. Shain RN: Psychosocial consequences of vasectomy in developed and developing countries. In Zatuchni GI et al (eds): Male Contraception: Advances and Future Prospects, pp. 34–53. Philadelphia, Harper & Row, 1986.

10. Howard G: Who asks for vasectomy reversal and why? BMJ 285: 490, 1982.

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