When a vasectomy is being performed, there are a number of ways it can be performed. Besides the minimally invasive, no-scalpel technique to make it as easy as possible on patients and minimize complications, Dr. Kavoussi believes the best way to obstruct the vas deferens is with a tissue interposition. There are a number of techniques that can be used to obstruct the vas deferens such as dividing the vas and tying it off, using a device known as an electrocautery to deliver electric energy to the inner portion of the vas deferens opening to seal it shut after it is divided, using metal clips to block the vas deferens, and performing what is known as a tissue interposition which is bringing an edge of loose tissue that is right along-side the vas deferens and sewing it in place between the divided ends of the vas deferens. This essentially makes a tissue wall between the divided ends to help keep them from trying to grow back together (known as recanalization).
There have been concerns about clipping or tying the divided ends of the vas deferens, with regards to the potential that this could compromise the microscopic blood supply to the end of the vas deferens beyond the tie or clip. This could result in necrosis (the tissue dying off) and then sloughing off, leaving an open end of the vas deferens, theoretically increasing the risk of the ends growing back together. Low-voltage electrocautery sealing the vas deferens openings reduces the recanalization rate to less than 0.5%. Vasectomy failure rates have been reported to be less than 1% when both ends of the divided vas deferens are blocked with clips. The tissue interposition technique between the divided ends of the vas deferens has been reported to reduce the recanalization rate even further, to nearly zero.
Dr. Kavoussi uses the techniques of sealing the vas deferens on both of the divided ends with electrocautery and then performing a dartos fascia tissue interposition to combine obstruction techniques to minimize the potential failure rates. This technique is advocated by the American Urological Association (AUA) clinical guidelines http://www.auanet.org/guidelines/vasectomy-(2012-amended-2015). Although there is no form of contraception that is absolutely 100% successful for everyone forever, this technique is awful close to it.