Recent research on vasectomy techniques*

Clinical Research Division, Family Health International, Durham, NC 27713, USA

Keywords: male sterilization; vasectomy; treatment efficacy; safety

1 Introduction

Vasectomy is a commonly used, highly effective method for the control of fertility in the human male. It is almost always performed as an outpatient procedure, is safer than tubal occlusion [1] and has few side effects [2]. The number of people relying on vasectomy as a method of contraception varies widely from country to country. Though vasectomy is highly effective, failures may occur due to re-canalization of the vas, surgical error, anatomical variants or failure of contraception during the post-operative waiting period. One of the disadvantages of this technique is that sperm are present in the posterior end of the vas following surgery and hence patients have to use alternative methods of contraception for a waiting period of 12 weeks to 15 weeks before relying on a vasectomy for contraception. This review summarizes recent research on vasectomy conducted by Family Health International, USA.

2 Vasectomy procedures and variations

Two procedures are commonly used to approach or gain access to the vas. The standard incision method has been in use for many years, and the "no-scalpel vasectomy" (NSV) was introduced by S.Q. Li in 1974 [3]. In the NSV method, after injecting anesthetic alongside the vas, an opening is made with pointed dissecting forceps tips to puncture the scrotum and expose the vas. The vas is then pulled through this puncture and is occluded using the surgeon's preferred method.

The methods adopted for the occlusion of the vas during vasectomy vary from surgeon to surgeon and are unrelated to whether a surgeon uses the NSV or the standard incision technique. The length of vas excised during vasectomy varies from none to 4 cm. Many surgeons use a simple ligation technique in which the vas is ligatured at one or both ends with a suture. Some surgeons leave the testicular end of the vas open with the objective of reducing pain from sperm granulomas. Some surgeons use fascial interposition while others fold back the vas to prevent re-canalization. An alternative to sutures is the use of one or more clips on the ends of the vas. Some surgeons are of the opinion that occlusion of the vas is more reliable when intraluminal cautery is used.

3 Advantages and disadvantages of no scalpel vasectomy

NSV is preferred over the conventional vasectomy as it has several advantages [2]. NSV does not involve cutting the skin of the scrotum and the scrotal opening made during NSV does not need suturing due to its small size. Additionally, the time taken to perform this procedure is shorter than for a conventional vasectomy.

Our research found that common complications, including the number of hematomas, the rate of infections and reports of mild and moderate scrotal pain were less in NSV patients when compared to the patients who underwent the standard incision procedure (Table 1). The NSV patients also reported resuming intercourse earlier (Figure 1). However, some surgeons reported that the NSV technique is more difficult to perform than the standard incision technique [2].

Table 1. Comparison of complications associated with NSV and standard incision method. * Includes all sizes of hematomas; only 2 required drainage, one in each group. (from Sokal et al., 1999).

Figure 1. Time to resuming intercourse after vasectomy by approach to the vas: Standard incision vs. NSV. o = NSV technique, = standard incision technique, P<0.05 (from Sokal et al., 1999).

A pilot study was conducted to observe the time taken to achieve azoospermia following vasectomy with standard method of ligation and excision without fascial interposition [4]. This study showed that many men did not reach azoospermia by 24 weeks. The full study confirmed these findings. 11.5 % of men were considered vasectomy failures based on semen analyses [5]. This prompted us to consider the efficacy of various occlusion methods in common use. Reviews of the literature have noted that data are not available from rigorous studies to support the use of one particular occlusion method over another [6, 7].

In a multi-center randomized controlled trial, conducted in collaboration with EngenderHealth, we compared the advantages of fascial interposition to ligation and excision alone. About 1 cm of each vas was removed at the time of vasectomy. Two definitions of vasectomy success are: (1) two consecutive azoospermic sperm samples, or (2) two severely oligospermic samples, with <100,000 sperm/mL. We also used a definition for early failure of >5 million motile sperm/mL at 14 weeks or later. An interim analysis was conducted after the first 414 participants had had time to complete 10 weeks of follow-up. The interim analysis results used only the time to azoospermia endpoint criteria and were complicated by differences between age groups. Recruitment was halted after 841 men had been enrolled because the interim analysis showed an advantage for fascial interposition [8]. The success rate with the use of fascial interposition was significantly higher at 22 weeks after vasectomy than ligation and excision alone (P<0.01).

While the time to azoospermia endpoint showed some age-related effects with younger men achieving azoospermia earlier, the numbers of vasectomy failures were similar across age groups. The overall failure rate based on semen analysis was 5.7 % in the fascial interposition group and 12.5 % in the non-fascial interposition group (manuscript in preparation).

We conducted a retrospective, population based study in Nepal that examined men who had had vasectomies between 1996 and 1999 [9]. The study sample included a total of 1 263 men from a population of about 33,000 who were vasectomized. Most surgeons who had performed vasectomies on the men observed in this study had used ligation and excision. 64.3 % reported excising more than 2 cm of vas and 9.3 % used fascial interposi-tion. One surgeon, who used a fold-back technique and also excised more than 2 cm of vas, appeared to have a significantly lower failure rate, but the study was not designed to evaluate occlusion methods. Out of a study sample of 924 men who provided semen samples, significant numbers of sperm (>500,000/mL) were observed in 23 patients at the time of evaluation between 12 months ~ 37 months after vasectomy.

Table 2 shows a tabulation of pregnancy status by semen analysis findings. Seven pregnancies were reported within three months of vasectomy while 25 pregnancies were reported to have occurred more than three months post vasectomy. Six of the pregnancies that occurred within three months were presumably due to unprotected intercourse during the waiting period, as no sperm were found in our study. Eleven pregnancies took place after three or more months of vasectomy in women whose partners did not have evidence of sperm in their semen. We assumed that these eleven pregnancies were due to transient re-appearance of sperm in semen, but it is also possible that some of the women might have had other sexual partners.

Table 2. Concordance of persistent sperm and pregnancy. *Including one case in which sperm were detected but the sperm concentration was less than 500,000/mL. ** Including 3 cases of pregnancy where fertilization date was not known; dates were imputed (from Nazerali et al., 2003).

In this study, the cumulative probability of all pregnancies after vasectomy was about 4 per 100 after 36 months. The study also showed that the likelihood of pregnancy was higher if the wife was less than 33 years of age at the time of her husband's vasectomy. No pregnancies were reported among women aged 33 or above.

In a retrospective research study conducted in China, it was found that the cumulative pregnancy rate in the partners of vasectomized patients was much higher than expected at 6.9 per 100 sterilized cases at 3 years and 9.4 per 100 cases at 10 years [10]. This indicates that the chances of vasectomy failure are high if a simple excision and ligation procedure is used in vasectomy, however Wang suggested that some of the pregnancies during the first year could have been due to intercourse during the waiting period.

We collaborated with Dr. Michel Labrecque to compare two occlusion techniques in conjunction with NSV [11]. For this study, we conducted a retrospective review of computerized records of vasectomy patients. In one technique, thermal cautery and fascial interposition were used for occlusion of the vas and one end of the vas was left open. In the other technique a single clip was applied to each end of each cut vas. One surgeon conducted all surgeries in this study.

The first semen analysis was conducted at about 14 weeks (Table 3). Findings show that while 64 % of patients with clips were azoospermic at the first semen sample, 83 % of patients were azoospermic following cauterization. Motile sperm with more than 20 million sperm per mL were found in 2.6 % of patients with clips while only 0.3 % of patients were found to have more than 20 million sperm per mL following cauterization. Based on subsequent semen analyses, a cumulative failure rate of 7.6 % was noted in patients with clips compared to 0.09 % for patients with cautery. While the cautery technique was clearly more effective, the open-ended aspect of the technique did not show any advantage with respect to reducing post-vasectomy pain.

Table 3. Effectiveness of thermal cautery vs. clips for occlusion of the vas: Results of first semen analyses at about week 14 (from Labrecque et al., 2002).

The findings of our recent studies indicate that vasectomy is not 100 % effective as judged by semen analysis or by occurrence of pregnancy. The method of occlusion of the vas is important to make vasectomy more effective. Fascial interposition clearly improves vasectomy effectiveness. Thermal cauterization may be more effective than ligation and excision with fascial interposition, but additional research is needed. With respect to low-resource settings, it should be noted that simple and inexpensive thermal cautery devices are available that are powered by AA alkaline batteries. Regardless of the method, all patients need to be counseled about possible failure and the potential for re-canalization and pregnancy.

In order to reduce the failure rate after vasectomy, further research is needed in two areas:

Numerous FHI and EngenderHealth staff, and clinical investigators in a number of countries contributed to the studies cited above. Partial support for this study was provided by Family Health International (FHI) with funds from the US Agency for International Development (USAID), Cooperative Agreement # CCP-A-00-95-00022-02, although the views expressed in this article do not necessarily reflect those of FHI or USAID.

References

[1] Hendrix NW, Chauhan SP, Morrison JC. Sterilization and its consequences. Obstet Gynecol Surv 1999; 54: 766-77.
[2] Sokal D, McMullen S, Gates D, Dominik R, the Male Sterilization Investigator Team. A comparative study of the no scalpel and standard incision approaches to vasectomy in 5 countries. J Urol 1999; 162: 1621-5.
[3] Li SQ, Goldstein M, Zhu J, Huber D. The no-scalpel vasec-tomy. J Urol 1991; 145: 341-4.
[4] Cortes M, Flick A, Barone MA, Amatya R, Pollack AE, Otero-Flores J, et al. Results of a pilot study of the time to azoospermia after vasectomy in Mexico City. Contraception 1997; 56: 215-22.
[5] Barone MA, Nazerali H, Cortes M, Chen-Mok M, Pollack AE, Sokal D. A prospective study of time and number of ejaculations to azoospermia after vasectomy by ligation and excision. J Urology 2003; In press.
[6] Schwingl PJ, Guess HA. Safety and effectiveness of vasectomy. Fertil Steril. 2000; 73: 923-36.
[7] Royal College of Obstetricians & Gynaecologists. Male and Female Sterilisation: Evidence-Based Clinical Guidelines No. 4. London: RCOG Press; 1999. p86.
[8] Chen-Mok M, Bangdiwala SI, Dominik R, Hays M, Irsula B, Sokal D. Termination of a randomized controlled trial of two vasectomy techniques. Control Clin Trials 2003; 24: 78-84.
[9] Nazerali H, Thapa S, Hays M, Pathak LR, Pandey KR, Sokal DC. Vasectomy effectiveness in Nepal: a retrospective study. Contraception 2003; 67: 397-401.
[10] Wang D. Contraceptive failure in China. Contraception 2002; 66: 173-8.
[11] Labrecque M, Nazerali H, Mondor M, Fortin V, Nasution M. Effectiveness and complications associated with 2 vasectomy occlusion techniques. J Urol 2002; 168: 2495-8.

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Correspondence to: David C. Sokal, MD, Family Health International, 2224 E NC Hwy 54, Durham, NC 27713, USA.
Tel: +1-919-405 1466, Fax: +1-419-831 6507
E-mail: dsokal@fhi.org
Received 2003-07-31  Accepted 2003-07-31
*Presented at the First Asia-Pacific Forum on Andrology, 17-21 October 2002, Shanghai, China.

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