A review of current options for male contraception, with a focus on no-scalpel vasectomy—its technique, benefits, risks, and possible complications. Important considerations for physicians who counsel men considering vasectomy, and future trends in male contraception currently under development.
Many simple, safe, and effective contraceptive options are available to men; here is a review of the current options and future possibilities.
"In a world where half of all pregnancies are accidents, and accidents lead to unexpected children, or abortions, or two decades of support payments, it would arguably behoove men to wise up and shoulder more responsibility for the birth control burden.” —Esquire Magazine, October 1999.
In birth control circles the commonly expressed opinion is that “Men will never take responsibility for birth control because they don’t have to do the birthing.”[1] There is, however, a growing understanding that future solutions, both at the individual level and in global population terms, will, of necessity, require the interest, involvement, and participation of men and their physicians.[2]
The United Nations report on world contraception shows vasectomy use at 10% to 15% of married couples in Canada, United States, parts of Europe, and China. It is significantly less in other parts of the world.[3]
Different cultures have various approaches to vasectomy. It is illegal in France. In Sweden a man only qualifies for a vasectomy if he has a minimum of four children and is over 40 years of age, or runs the risk of transmitting a serious inheritable disease.
The American National Survey of Men reports vasectomy performed on 13.5% of white men, but only 1.6% of black men in the US. In both races, vasectomy prevalence was higher for men with a high school education than for those without (13.7% vs 4.8%).[4]
In 1995 a survey of vasectomy providers was conducted jointly by the Center for Disease Control, AVSC International (the organization that brought no-scalpel vasectomy to the world) and the Tulane University School of Public Health.[5] This revealed that 500 000 vasectomies were performed in the United States that year. Of those, 30% used the no-scalpel technique.
Current birth control choices for men are limited to abstinence, withdrawal, condoms, and vasectomy. A host of new pharmacological and technological contraceptives for men are said to be just around the corner, as they have been for more than 40 years.[6]
Abstinence from intercourse is not necessarily sexual inactivity per se. Outercourse is probably a better term to describe sexual activity other than peno-vaginal penetration. When combined with the Fertility Awareness Method, also known as periodic abstinence, or the Billings Method, abstinence has, at best, an annual failure rate of 9%.
Like abstinence, the withdrawal of the penis prior to ejaculation is very user-dependent, and therefore unreliable. Even when performed perfectly, sperm can be present in pre-ejaculatory secretions and result in pregnancy.
Pregnancies with typical condom use occur in 14% of couples per year. With exemplary use the rate drops to about 4%, but exemplary use is rare.
Water-based lubricants should be applied liberally to prevent friction tearing. Oil-based lubricants like petroleum gel or hand creams can disintegrate latex rapidly. The penis should be withdrawn by the male immediately after ejaculation, holding the rim of the condom onto the shaft of the penis during withdrawal. If thrusting persists after ejaculation, the condom can slip off of the detumessed penis and into the vagina.
When a condom accident does occur, it behooves the male to inform his partner so that emergency contraception can be considered. In one survey, 40% of male college students did not inform their partner when a condom broke or slipped, so this contraceptive opportunity was lost.[7] This, more than anything, exemplifies the need to put more effective effort into engaging men in the dialogue and into changing the attitudes of some men with respect to their sexuality and their partners’ health.
Latex allergy occurs in 15% of the population, and is most prevalent in health care workers, including doctors. In Vancouver, The Rubber Rainbow Condom Company sells non-latex condoms. The deproteinized latex condom, recently introduced in Europe, is said to be safe and effective for latex allergy sufferers.[8] The female condom is also a non-latex product.
Significant percentages of men are unable to maintain erections with condoms due to the loss of sensation or to the loss of spontaneity.
Vasectomy is a surgical procedure that involves cutting and blocking the vasa in the scrotum to prevent sperm from reaching the ejaculate. Since the success of reversal is not guaranteed, vasectomy should be viewed as permanent sterilization. Cryopreservation of sperm prior to vasectomy is a reasonable option for those who wish to mitigate against future regret.
In Canada, until the early 1960s, the Canadian Medical Protective Association warned doctors that they would be performing vasectomies without CMPA support if they faced lawsuit, since the operation was thought to be illegal in Canada. Only in 1961, armed with a legal opinion that this position was indefensible, some physicians began to perform vasectomies openly in the Vancouver area.[9]
No-scalpel vasectomy (NSV) was developed in China in 1974 by Dr S.Q. Li at the Chongking Family Planning Institute. It was introduced to the United States in 1988. Dr Marc Goldstein witnessed the operation in China, then arranged a world team, under the direction of the World Health Organization and AVSC International, to investigate it. A randomized study of 1203 vasectomies performed in 1 day at the King’s Birthday Vasectomy Festival in Bangkok revealed an eightfold lower incidence of bleeding and infection with the NSV group compared to standard incision vasectomy group.[10] Subsequent studies have shown similar results, though one 1999 study showed little difference.[11] No studies showing better results with traditional techniques have been reported.
No-scalpel vasectomy technique
Traditional vasectomy is usually performed under a field block. Local anesthetic is infiltrated into multiple tissue planes, swelling the tissue, so the vas must be held firm. The perivasal nerve block used with NSV anesthetizes a wider area, without obscuring the vas, because the perivasal nerves are blocked proximal to the operative field. First a small subcutaneous wheal is raised, then 2 cc of local anesthetic is deposited a few centimetres above this site, along the vas, on both sides. The right vas is brought directly under the skin using the three-finger technique, then clamped to the skin with the small dedicated ring fixation clamp (see the figure [8]). The skin is punctured, then spread by the tines of the vas dissector. This instrument is essentially a mosquito forceps, without the corrugations, and sharpened to points. The vas is hooked (skewered) on one point of the dissector and elevated. As the ring clamp is released, a loop of vas is thus pulled up from the wound, then re-grasped within the arms of the ring clamp. The vas can then be blocked and returned to the scrotum, and the procedure repeated on the left vas through the same 3 mm puncture.
Variations in vas blocking technique
NSV is only a method of accessing the vas. Methods of blocking the vas vary widely among surgeons. Many are considered acceptable,[12] but a growing body of evidence suggests that the open-ended technique is preferable since it minimizes pain and enhances the potential for successful reversal.[13] Immunohostochemical studies have demonstrated that the mechanical obstruction of the testicular end of the vas results in damage to the testis and epididymis by elevating hydrostatic pressure, generating reactive oxygen species, and initiating specific immune responses.[14] These events result in basement membrane changes in the seminiferous tubules and elsewhere in the testicle. In an experimental rat model these structural changes were absent after open-ended closure when examined 1 year later.[15]
The additional step of interposing fascia between the two cut ends can be combined with either open- or closed-ended techniques to further reduce the chances of failure. In this maneuver, the anterior and posterior aspects of the vas sheath are clipped or sewn together to separate the vas ends into different tissue planes.
In the author’s practice, the prostatic end of the vas is blocked with intraluminal heat cautery to a depth of 1 cm. The cauterized end is immediately pinched to ensure a solid plug of scar tissue in the lumen. This method avoids clips or sutures applied directly on the vas, which may cause necrosis and distal sloughing, hence possible recanalization. Fascial interposition is accomplished with clips.
For skin closure, the use of a stitch, skin tape, or nothing, has been standard procedure. The use of cyanoacrylate (Dermabond Skin Adhesive) to seal the small puncture is a recent improvement. This method was first employed by Dr Ron Weiss in Ottawa. It allows patients to shower the same day, and no wound care is required.
Risks and complications after vasectomy
For acute postoperative pain, NSAIDs have been shown to be superior to acetaminophen/codeine in a randomized study[16] because they block the inflammatory process. Prostaglandins participate in many genital and sexual events and mechanisms, in both men and women, including erection, ejaculation, uterine contraction, swelling, clitoral engorgement, lubrication, and others. According to immunohistochemical studies,[17] nowhere in the body (specifically, the rat’s body) is there a higher concentration of COX-2 receptors than in the distal vas deferens. This abundance accounts for the propensity to swelling, inflammation, scrotal edema, vasitis, and epididymitis. It occurs in 30% of men, usually around the third or fourth day postoperatively. The pain is usually minor, and settles spontaneously within a week. It can be very worrisome to the patient who was doing well until then, and may result in the misdiagnosis of infection or hematoma. Many vasectomists therefore prescribe a routine course of NSAIDs for 1 week.
Overall, reported incidences of hematoma vary from 0% to 5%, but it is unclear from study to study whether small hematomas are included, since usually no size definition is in the reports. When a significant hematoma does occur, a scrotal ultrasound and a urologist’s opinion regarding advisability of drainage should be sought, despite the fact that surgical drainage is rarely recommended.
Infection is best defined by a requirement for an oral antibiotic or more, but the criteria are not clear in most studies, and the data is unreliable. Abscess formation is said to occur on rare occasions and may require excision or drainage. A recent case report of Staphylococcus lugdunensis causing endocarditis following vasectomy[18] underlines the need for vigilance despite the low risk.
Subacute pain, from mild to severe, intermittent to constant, is reported in 6% to 15% of post-vasectomy men. Small inflammatory masses or sperm granulomas can be associated with the pain. No precise definition of subacute pain has been standardized across the literature. Treatment with NSAIDs is usually effective, but compliance can be problematic. Moss noted a drop in incidence of pain, from 6% to 2%, with the change to an open-ended technique.[13]
Chronic post-vasectomy pain syndrome is said to occur in fewer than 1 per 1000 cases, and the cause is unknown. There are many features in common with other chronic pain syndromes. Treatment is in steps. Local injection, testicular denervation, excision of a painful granuloma if one exists, epididymectomy, vasectomy reversal, and orchiectomy have all been described.[19] In a recent study[20] no histologic differences were evident in vas tissue excised from these patients when compared with tissue excised from vasectomy reversal patients.
Risk of prostate cancer after vasectomy
The perceived association between prostate cancer and vasectomy first received widespread attention in 1993. Giovannucci’s cohort analysis of data on the husbands of The Nurse’s Health Study enrollees found an increased risk of prostate cancer in those who reported vasectomy. The same study, incidentally, reported lower overall mortality rates in the vasectomized men than in their matched controls.[21]
A meta-analysis published in 1998[22] and the accompanying editorial[23] argue that any weak associations found are the results of selection bias based on the fact that vasectomized men had seen a doctor by definition (most likely a urologist). They were therefore more likely than the non-vasectomized cohorts to undergo screening digital rectal exams and to seek medical help early when symptoms developed. They also speculate about an element of publication bias, in that they found nine studies showing no association that were never published.
In the literature, few studies define exactly what is meant by vasectomy failure in terms of sperm counts plus or minus motility, and at what point in time. Generally, the persistence of any live sperm 6 months after surgery is a reasonable indication for repeat vasectomy if the patient desires it. Occasional non-motile sperm persisting beyond 6 months, with no increase in numbers over time, is termed a technical failure. While this may be a theoretical concern, it carries no higher a risk of pregnancy than complete azoospermia and the patient can be reassured, provided he is informed of the situation, and monitoring of the semen continues for a full year.
In some practices as many as 50% of vasectomites do not return for semen testing. This statistic, called the truancy rate, should be disclosed in all reports of failure rates and factored into the data. Unfortunately, it is never mentioned. For example, five failures in 500 vasectomies with a truancy rate of 50% in that practice would have a reported failure rate of 1%. The actual failure rate would really be 2%, based on five failures in the 250 patients actually tested.
DNA-confirmed paternity with apparent azoospermia after vasectomy has been documented with an incidence of approximately 1 in 4000.[24] In these rare cases, the intermittent appearance of small quantities of sperm through micro-canalization is postulated. The alternative explanation is too religious to fathom. Combining the usual anxieties of an unexpected pregnancy with the inevitable uncertainties about paternity and fidelity can lead to divorce, physical abuse, reactive infidelity and depression. The physician has a critical role in providing open, logical, accurate, ethical, and supportive advice to help the partners deal with this diagnosis.
The 1995 CDC survey[5] points out that no consensus exists for post-vasectomy semen analysis, and no consistent practice governs the testing procedures recommended by vasectomists in the United States.[7] There is also no consistent interpretation of results, particularly with respect to the significance of occasional non-motile sperm persisting after vasectomy. It can be difficult to decide where to draw the line between caution and folly. Testing at 6 weeks and 15 ejaculations post-op, with a retest 1 month later to identify any rare case of early recanalization, is the author’s recommendation. Some authorities suggest waiting 3 months to perform the first test, but longer waits tend to promote non-compliance. Once the occasional condom is forgotten and no pregnancy ensues, some men will wrongly assume that the vasectomy must have worked and decide, therefore, that they need not bother with testing.
A survey of vasectomists in BC was conducted by the author in May 2000 (see the table). Of the respondents, most estimated their truancy rate to be between 5% to 10% of patients. Studies consistently report rates of 30% to 50%. For this reason, a telephone or mailed reminder to patients at 3 months’ post-op is advocated by some.
A home test kit to analyze semen for presence of sperm is said to be close to market, and will undoubtedly change the ways in which we assess and document the success of a vasectomy in future.
The risk of regret is said to be 2% to 6%, the majority being the result of marital breakup and the desire for a child with a new partner. Reversal, or vaso-vasostomy, is a non-insured service in British Columbia. The cost, excluding facility and anesthesia fees, varies from $1200 to $3500. American fees are as high as US$15 000.
Some urologists operate using magnifying loupes, but a microsurgical repair offers the best chance for a near-flawless anastamosis, and better results. Most experienced American microsurgeons use 10-0 suture to close the vas mucosa, and add two or three more layers of closure.
First, scarred areas are dissected until healthy vas tissue is identified. A smear from the testicular end is checked under a microscope, looking for sperm. If absent, then the original vasectomy probably developed leaking, scarring, and obstruction of the epididymis, commonly called a blowout. The surgeon would then modify the procedure to a vaso-epididymostomy to get back to viable sperm. These blowouts occur progressively over time with closed-ended vasectomy procedures. This may contribute to the better prospect for successful reversal with open-ended vasectomy, regardless of the duration of time elapsed.
Doing reversal through a no-scalpel incision has been advocated by some, but should be avoided in the opinion of one expert (personal communication with Dr Marc Goldstein, Cornell University Center for Male Reproductive Urology, 1999). Following a vasectomy the blood supply to the vas can be tenuous, and pulling the vas up through a tight opening could compromise vascularity even further. Maximizing perfusion to the anastamosis is essential to optimizing fertility, not only because vasa are likely to re-occlude postoperatively if perfusion is marginal, but also because minor hypoxic stress on sperm, oxidative and otherwise, can affect sperm fertility in subtle ways. The Cornell University Reproductive Urology web site (maleinfertility.org [9]) is an excellent resource for state-of-the-art information in vasectomy reversal and for management of male infertility in general.
The development of the no-scalpel method of bringing the intact vas to just under the skin surface has led to an interest in other percutaneous techniques to occlude the vas lumen.
Cyanoacrylate (Dermabond) injection is widely used in China. To ensure successful cannulation, prior to blockage red dye is injected into one vas and blue into the other. When the two dyes mix, brown urine results, indicating successful cannulation bilaterally. The absence of either the red or the blue dye in the urine indicates that the vas on that side has not been successfully cannulated.[25] Cyanoacrylate did not receive approval for internal use in North America until recently, when approval was obtained in the United States for occlusion of small intracranial aneurisms.
Silicone blocking techniques and devices have been under study in various forms. One recent effort, Vasoc, was poised for investigation by the World Health Organization based on promising preliminary reports from Indonesia. The study was cancelled when a failure rate of 85% was encountered.[26] Other silicone devices are also under study.
An injectable, reversible hydrogel, styrene maleic anhydrous (SMA) is currently in advanced clinical trials in India.[27] Work on other novel methods of vas occlusion is ongoing around the world.
Transcutaneous occlusion, with ultrasound or laser tissue welding, is also under investigation with good success in animal models. Ultrasonic occlusion seems to be the better technique to date (personal communication with Dr Marc Goldstein, March 2000). Many patients claim to have heard about laser vasectomy, but they are mistaken; it is not commercially available anywhere.
Future trends in male contraception
Work on the male pill has been in progress for 40 years, but is not likely to be available for general use at any time soon, despite recent press reports to the contrary.
Spermatogenesis, a 72-day process, is directed by pituitary (follicle-stimulating hormone). Administration of testosterone shuts down follicle-stimulating hormone production, but causes side effects. The addition of progesterone allows for the inhibitory effect at lower testosterone doses and is better tolerated.[28] Currently, effectiveness is only 90% to 95%, which is not reliable enough for most couples. There are still potential side effects, primarily to lipids, prostate, and possibly sexual function, that need to be delineated. Also, the long-term effects of progesterone on men are not known, although low concentrations are normally present in men.
Inhibition of spermatogenesis by any means causes a decrease in testicular size, which is cosmetically unacceptable to many men and their partners. Delays in onset of contraceptive effect for up to 3 months, as well as delays in regaining fertility, also mitigate against the prospect of widespread popularity for this method.[29]
Methods that affect sperm function as opposed to spermatogenesis hold more promise in some views. Sperm do not become motile, or achieve the ability to fertilize, until they leave the epididymis. This final maturation is not fully understood, but various drugs are known to impair the process. Triptolide, derived from a Chinese herb, is one such product under study.
Fertilization also requires the sperm to dissolve the outer layer of the female’s ovum, to fuse to it, and to empty its genetic package therein. This process, termed hyperactivation, involves a complicated reaction between the sperm’s plasma membrane and the acrosome, a concentration of enzymes in the spermhead. This is activated via a calcium-dependent channel, and nefedipine has been shown to inhibit it in vitro.
P34H is the protein on the surface of the spermhead that initiates the acrosome reaction to bind to the surface of the ovum. A vaccine to produce anti-P34H antibodies is currently in development at a Canadian biotech firm. It is showing considerable promise and is said to be 5 to 10 years from market.
Despite these promising avenues of research, there are many cultural, societal, and interpersonal issues with male contraception yet to be overcome. It is generally accepted that marketing these products to men may be difficult, as is the marketing of many health products to men.
Lack of compliance with daily medication might become an issue for many couples. Women would have to trust a partner, who doesn’t risk pregnancy, to take it. Some companies are considering the marketing of a home-test kit to chemically confirm the absence of sperm as proof of his compliance. This could certainly put a damper on trust, spontaneity, and intimacy.
Some cultural theorists and gender futurists, however, hold the opposite view, that once a safe, convenient, and reliable contraceptive is available, men will flock to take it. The resultant control of their own fertility will change the definition of masculinity. Just as the birth control pill did for a generation of women in the sixties, this pill will provide a new freedom for men that could herald the start of yet another sexual revolution.
We shall see.
Survey of all BC urologists and known GP vasectomy providers, May 2000.*
Practice |
Urologists (N=10) 6 |
GPs (N=6) 5 |
Barry Rich, MD
Dr Rich is a general practitioner in Surrey, Vancouver, and West Vancouver, with a practice limited to no-scalpel vasectomy and men’s sexual dysfunction. He is on staff at Surrey Memorial and Lions Gate Hospital, chairs the Men’s Health Committee of the BCMA Council on Health Promotion, and is a member of the Canadian Male Sexual Health Council.
Links
[1] https://bcmj.org/node/621
[2] https://bcmj.org/author/barry-rich-md
[3] https://bcmj.org/print/articles/male-contraception-and-no-scalpel-vasectomy
[4] https://bcmj.org/printmail/articles/male-contraception-and-no-scalpel-vasectomy
[5] http://www.facebook.com/share.php?u=https://bcmj.org/print/articles/male-contraception-and-no-scalpel-vasectomy&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton&via=BCMedicalJrnl&tw_p=tweetbutton
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[7] https://bcmj.org/javascript%3A%3B
[8] https://bcmj.org/sites/default/files/public/Vasect5.gif
[9] http://www.maleinfertility.org
[10] https://bcmj.org/modal_forms/nojs/webform/176?arturl=/articles/male-contraception-and-no-scalpel-vasectomy&nodeid=56
[11] https://bcmj.org/%3Finline%3Dtrue%23citationpop