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Background
According to a guideline on sterilization by the American College of Obstetricians and Gynecologists (ACOG, 2003), approximately 500,000 vasectomies are performed annually in the United States by urologists, general surgeons, and family physicians.
During vasectomy, an incision or puncture (no-scalpel technique) is made in the scrotum and the vas deferens is then cut to disconnect it, thereby interrupting the sperm's route from the testicles to the penis. A piece of the vas is removed (to reduce the chances of the 2 ends of the vas rejoining) and the 2 ends are then clipped, tied, or cauterized. Fascial interposition, in which one end of the vas is covered by either the sheath tissues of the vas itself or with adjacent connective tissue, is also widely used in conjunction with occlusion techniques to reduce the risk of re-canalization. A controversial and less widespread practice involves leaving the testicular end of the vas unsealed to allow sperm to flow out of the vas in order to minimize pressure on and damage to the epididymis (Errey et al, 1986). Once the vasectomy is performed, the testicles still generate sperm, but their movement is blocked.
The rate of vasectomy failure, defined as lack of azoospermia on follow-up semen analysis (SA) or presence of pregnancy, has generally been reported to be between 0 % to 2 % (Cook et al, 2004; ACOG, 2003). The 3 main causes of vasectomy failure are operative failure, unprotected intercourse before the semen is cleared of sperm, and spontaneous early or late recanalization of the vas (Cook et al, 2004). Failure rates are reportedly lower when traditional vasectomy is performed by more experienced surgeons (Schwingl et al, 2000). Vasectomy is considered a low-risk procedure with fewer than 3 % of cases resulting in complications; complications include: infection, bleeding, hematoma, acute and chronic pain and congestive epididymitis.
Since the late 1960s, attempts have been made to develop an alternative method of vasectomy that would be more easily reversible than a standard vasectomy. Most of these efforts focused on the use of mechanical valves that could be opened and closed. The Vasclip, a locking ligation clip the size of a grain of rice, was cleared for marketing by the Food and Drug Administration (FDA) based on a 510(k) application. Thus, the manufacturer was not required to supply the evidence of effectiveness that would be required to support a pre-market approval application (PMA). The FDA 510(k) summary of substantial equivalence stated the Vasclip is identical in use to the Hem-o-lok, a polymer ligating clip that is used to close off vessels that supply blood to organs.
An unpublished prospective clinical study available through VMBC, LLC, the VASCLIP Company and on their website, reported the results of 124 men who had the Vasclip procedure. Three of the men (2.5 %) did not become infertile due to improper placement of the Vasclip, 0.8 % developed a hematoma and 0.8 % developed a sperm granuloma. Sixty-eight of the patients who returned for a SA all tested as infertile (no live sperm) at an average of 373 days after the Vasclip procedure and all of the 78 patients who returned for a SA tested as infertile at an average of 853 days after. Reported range of significant pain was 5 %. Statistics on reversal are not yet available.
The potential for enhancing reversal is one main rationale for the use of vas occlusion with clips (Schwingl et al, 2000). In addition, the manufacturer states that the Vasclip results in lower complication rates than conventional male sterilization procedures. However, it is not known whether the Vasclip compresses the vas so tightly that the blood supply to the underlying portion of vas is permanently damaged. There is no adequate evidence in the peer-reviewed published medical literature that the Vasclip has a reduced late failure rate, lower complication rate or improved reversal rate then traditional vasectomy.
There is inconsistent evidence regarding the effectiveness of the Vasclip implant compared to standard vasectomy procedures. Kirby et al (2006) examined if the Vasclip implant procedure would (i) be equivalent to vasectomy in producing azoospermia, (ii) produce greater patient satisfaction post-operatively, and (iii) result in lower complication rates, post-operative pain, hematoma formation, spermatic granuloma, and surgical site infection when compared with historical controls. Successful sterilization, defined by azoospermia at 10 to 14 months, was observed in 116 of 119 subjects. The authors stated that effectiveness seemed to be equivalent to that of vasectomy, although the study did not include an internal control group of subjects receiving vasectomy. The authors observed that the incidence of post-operative pain and hematoma formation was similar to that which had been reported for standard vasectomy. The Vasclip procedure also had similar infection rates. The authors reported that the Vasclip procedure seemed to have lower rates of sperm granuloma formation compared to standard vasectomy. In 3 subjects with persistent presence of sperm, histological examination after traditional vasectomy indicated that misalignment of the device led to partial vas incision with recanalization. The authors reported that 99 % of survey respondents would recommend that other men considering a vasectomy have the Vasclip procedure.
On the other hand, Levine et al (2006) found persistent motile sperm after the Vasclip procedure. The authors assessed the effectiveness and mechanism of failure in a small case series of Vasclip vasectomies. Microscopic semen analysis was done a minimum of 4 weeks post-operatively and after at least 15 ejaculations. The number of sperm and motility were quantified in 15 or more high power fields. Successful vasectomy was defined as 2 consecutive post-operative unspun semen analyses containing no sperm. Patients with failed vasectomy underwent bilateral surgical removal of the vas deferens segments containing the ligation band for gross and histological analysis. Six of 8 patients (75 %) were deemed azoospermic after 2 semen analyses at a mean follow-up of 7 and 11 weeks post-operatively, respectively. Two of 8 patients (25 %) had semen analyses containing multiple motile sperm after vasectomy. In the 2 failed cases 1 side was patent, as demonstrated by vasal cannulation and irrigation with dilute methylene blue despite a well-positioned, intact and secure ligation band. Histological analysis showed extravasation and sperm granuloma on the patent side. The authors concluded that the Vasclip was found to fail at an unexpectedly high rate. Pathological analysis suggests sperm extravasation and fistula tract formation as the mechanism. One failure resulted in an unwanted pregnancy, which demonstrates the need for patient counseling regarding post-operative follow-up.
Cook et al (2004) systematically reviewed the evidence comparing male sterilization techniques. They identified 2 controlled clinical trials (Gupta et al, 1997 [n = 110]; Clausen et al, 1983 [n = 79]) comparing vas occlusion with clips (no transection of the vas) versus a conventional vasectomy technique (transaction of the vas with both ends of the vas ligated and looped back). Neither trial found a significant difference between the 2 groups with regard to the primary outcome of failure to reach azoospermia. However, Cook et al (2004) stated that no firm conclusions can be made about the comparative effectiveness, safety, and acceptability of these vas occlusion techniques due to the poor quality of the studies.
In a Cochrane review on vasectomy occlusion techniques for male sterilization that include excision and ligation, thermal or electrocautery, mechanical/chemical occlusion, as well as vasectomy with vas irrigation or with fascial inter-position (Cook et al, 2007), the authors concluded that for vas occlusion with clips or vasectomy with vas irrigation, no conclusions can be made as those studies were of low quality and under-powered. Fascial inter-position reduced vasectomy failure. An intra-vas device was less effective in reducing sperm count than was no-scalpel vasectomy. They noted that randomized controlled studies evaluating other vasectomy techniques were not available; more and better quality research is needed to examine vasectomy techniques.
The Pro-Vas occlusion technique utilizes a titanium spring ligation clip that stops the flow of sperm without the need to cut or burn the sperm ducts. Pro-Vas has also been reported to result in less post-procedure pain and quicker return to normal activities compared with traditional vasectomy. Additionally, there were no complications following Pro-Vas occlusions, however, it is acknowledged the number of patients is not sufficient to provide statistically significant results. According to Dr. Swartz, the Pro-Vas occlusion technique has the potential to simplify and standardize the vasectomy technique. It may provide less experienced vasectomy surgeons a means for achieving clinical results similar to those of experienced surgeons. The Pro-Vas technique also spares sacrificing the vasal artery. Dr. Swartz added that there should be a lower re-canalization rate with the Pro-Vas method because the spring ligation clip cannot dislodge or ever lose its constant low-pressure occlusion force. Additionally, the clip is designed not to apply so much pressure that may result in necrosis – a situation that sometimes occurs with other types of ligatures. Should the patient ever change his mind with regard to his vasectomy, reversal of the Pro-Vas procedure should be much easier as the clip is very easy to identify and dissection to find the two occluded ends of the vas will be much simpler. Patient acceptance may be higher with the Pro-Vas occlusion technique than traditional vasectomy because overall quality of the outcomes may be improved. However, these hypotheses need to be confirmed by additional clinical studies. (http://www.prnewswire.com/news-releases/phase-i-pro-vas-effectiveness-study-presented-at-aua-meeting-123455694.html).
Michielsen and Beerthuizen (2010) performed a systematic Medline/PubMed and Cochrane Library review of the literature with regard to technique, effectiveness, safety and complications of male sterilization. Vasectomy is an outpatient procedure which can be performed under local anesthesia. The vas deferens is accessed by means of either a conventional incision with a scalpel or by using the"'no-scalpel technique". A closed-ended vasectomy (by means of suture ligature, surgical clips or electro-cautery) or the open-ended alternative is then carried out. Each of these techniques has both advantages and drawbacks. Fascial interposition has been shown to reduce the risk of failure. A promising alternative for occluding the vas consists of placing an intra-vas device. Hematoma and pain are the most common complications. Non-steroidal anti-inflammatory drugs, narcotic analgesics and neuroleptic drugs are effective for treatment of pain. The success of vasectomy reversal ranges from 30 to 60 %. The data on record convincingly demonstrate that vasectomy is a safe and cost-effective intervention for permanent male contraception. The no-scalpel vasectomy under local anesthesia is recommended. Occlusion of the vas is most successful when performed by means of an electrocautery; fascial interposition should complete the procedure.
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