In this study, we have demonstrated that vasectomy by epithelial curettage with the Vas-X can effectively sterilize men at 1 year of follow-up. However, three of the 12 men in this pilot trial, despite attaining very low sperm concentrations 3 months after the vasectomy, were not effectively sterilized. These men experienced a 'late' failure of their vasectomy (as defined by Labrecque et al.
), with the re-appearance of sperm in their ejaculates between 4–6 months after the initial epithelial curettage procedure. Because two of these men were azoospermic and the third was near-azoospermic before experiencing failure, it appears that the procedure was initially successful in occluding the vas, but the vas was able to re-canalize several months after the procedure. This re-canalization could be directly visualized in the two individuals who returned for a repeat vasectomy. Microscopic analysis of the segment of the vas that underwent epithelial curettage with the Vas-X revealed what appeared to be re-growth of new vas-like channels through the treatment area. This finding implies that in these individuals the injury to the epithelium mediated by the Vas-X was not sufficient to prevent epithelial re-growth, possibly due to insufficient compression of the vas against the blades of the microcurette before it was extracted. As a result, the technique of epithelial curettage will require further refinement to determine whether it is a viable alternative to cautery for vasectomy. Improvements such as curettage of a longer segment of the vas and/or instillation of a caustic or toxic agent, such as silver nitrate, into the lumen of the treated segments of vas to prevent re-canalization could be considered for future study.
In addition, we chose to leave the abdominal and treated ends of the vas connected by an 'unroofed' middle segment, which also underwent epithelial curettage with the Vas-X. In theory, this was intended to prevent the abdominal and testicular end of the vas from re-anastomosing while the tissue was forming a luminal scar. A similar method has been extensively tested using electrocautery 14
. However, it is possible that in the setting of epithelial curettage, this approach instead allowed for epithelial stem cells to re-populate the area and form the new lumens visualized in the tissue specimens from the subjects undergoing repeat vasectomy for failure. Moreover, in contrast to the reported histology of the vas in men undergoing cautery vasectomy, which reveals a fibroblastic scar 15
, the histology after treatment with the microcurette is predominantly muscular. Whether this accounts for the apparently increased risk of re-canalization is unknown. Future studies of epithelial curettage may need to consider removing the middle segment to prevent the types of failure observed in this study.
If the technique of epithelial curettage for vasectomy can be optimized, it might offer several advantages over current vasectomy techniques that rely on suture or cautery. First, it can be performed with the no-scalpel approach, which is widely practiced and acceptable to patients; however, unlike the no-scalpel technique, it does not require that the vasal blood supply be stripped from the vas deferens, thereby potentially decreasing the potential of vascular injury and bleeding complications. Second, there is no unpleasant smell of burning flesh associated with cautery, and because there is less tissue damage than with cautery, it is possible that men undergoing vasectomy by epithelial curettage might experience less pain. Indeed, men in this study experienced minimal post-operative pain from their procedure, with 11 of 12 men reporting no pain at 1 month. Lastly, if vasectomy via epithelial curettage can be perfected, it may prove easier to use in less-developed areas of the world as the technique is easy to learn and requires less operative skill than other techniques. Moreover, the Vas-X has a very simple design, is re-usable (with sterilization) and does not require an electrical supply for use.
Notably, three of the nine subjects in whom the procedure was successful continued to have rare, non-motile sperm in their ejaculates. The presence of these rare, non-motile sperm has been observed in up to 40% of men undergoing vasectomy 16
. Long-term follow-up has shown that the vast majority of such men eventually become azoospermic 17
. Therefore, the presence of rare, non-motile sperm is thought to be consistent with a successful vasectomy. However, given the novel nature of this procedure, these subjects will continue to be followed up to insure that they do not experience very late failures.
In conclusion, this is the first report of the use of epithelial curettage as a method of vasectomy. We have demonstrated that this approach to male sterilization is effective in a majority of men; however, a subset of men, after initially achieving extremely low sperm counts, failed and experienced the re-appearance of sperm in their ejaculates. Analysis of tissue from these failures demonstrates vasal re-canalization, implying that future studies of this technique will require more extensive curettage, or other measures to prevent late failures. If improvements to the technique are successful, epithelial curettage might offer a simple alternative to cautery or ligation vasectomy for the provision of male sterilization.