Microsurgery is a subspecialty of surgery involved in reconstruction of small anatomic structures. It was developed initially in the 1960's to facilitate the repair of tiny blood vessels, using an operating microscope and surgical techniques already in use for middle ear surgery. It soon found wide application, especially in hand surgery and reconstructive plastic surgery.
In the 1970's, urologic surgeons and infertility specialists began to apply microsurgical techniques to the management of sterilization reversal, especially fallopian tube reconstruction (in women) and vasectomy reversal.
Before microsurgery, vasectomy reversal had been attempted for many years, with universally poor results. Many variations of non-microsurgical techniques were developed to improve the success rates, including the use of stents and optical magnification with jeweler's loops. However, very little progress was made until the introduction of true microsurgical technique. Epididymal reconstruction prior to the use of microsurgery virtually always failed, and was rarely if ever attempted. This led to the general presumption that vasectomy could not be reversed with any reliability, and should not even be undertaken after 10 years post vasectomy.
The first critical element in microsurgery is the operating microscope. These come in a wide variety of manufacturers and capabilities depending on their specific surgical use. They all share common features, however. There is a heavy moveable stand and pedestal for stability, with an attached articulating arm which allows the optical portion to swing over the surgical area. The optical head generally has one or two pairs of binocular eyepieces, and a high intensity light source, allowing the surgeon (and an assistant, if one is needed) to see the operating area in high magnification (generally 15-40x) while having the hands free. The more sophisticated microscopes have foot pedal power control over zoom, focus, light, and position.
Specialized instruments have been developed to allow surgeons to work under high magnification with exceedingly small sutures. These instruments are machined to demanding tolerances, and must be treated with utmost care. Many microsurgeons purchase and maintain their own micro instruments to insure that they remain in perfect condition.
The sutures (stitches) used for microsurgery are exceedingly small, much finer than a human hair. Unless viewed against a white background, they are nearly invisible to the human eye.
A microsurgical suture may be manufactured from either permanent or absorbable material. They are fabricated by hand, and the needle is attached to the suture under a microscope at the manufacturer. For microsurgical vasectomy reversal, permanent, non-absorbable sutures are commonly used. Dr. Finnerty uses only 9-0 and 10-0 monofilament nylon sutures for vas-to-vas and epididymal repairs, since these have the optimal physical characteristics and strength for vas reversal surgery. Absorbable sutures have sufficient strength for vas repairs, but tend to cause more inflammation during the healing process.
There are several methods of microsurgical reversal of the vas deferens. The most common are one layer and two layer techniques.
In a one layer repair, the sutures are placed through the entire wall of the vas and into the central opening (lumen). Generally, about 6-8 sutures are used for each vas. While some surgeons have reported good results with this approach, many microsurgeons believe that it does not align the central channel of the vas as accurately as is possible with a two-layer technique. It may be a preferred technique for less experienced microsurgeons, however, since it is easier to perform.
A two-layer repair is more commonly performed by experienced microsurgeons, as most feel it provides more precise alignment of the lumen, reducing the chances for scarring and obstruction. In a two layer repair, sutures (9-0 nylon) are first placed in the muscular layer of the vas, providing rough alignment and mechanical strength. Additional finer sutures (10-0 nylon) are then placed in the central channel, in the mucosa (a thin smooth membrane which lines the lumen of the vas). There is often a significant difference in the diameter of the lumen above and below the vasectomy site, because of the increased pressure below. The use of these mucosal sutures provides very accurate approximation of the mucosa, even when the lumen diameters are quite different, reducing the chance for sperm leakage and inflammation.
The number of mucosal sutures used varies with the diameter of the vas lumen and the surgeon's technique. More sutures does not necessarily result in better success. In Dr. Finnerty's experience, between 6 and 8 mucosal sutures, and between 8 and 12 muscular sutures (depending on vas diameter) provide the best chances for accurate alignment.
When back pressure from vasectomy causes thinning and sperm leakage in the epididymal tubule, the resulting obstruction prevents sperm from reaching the vasectomy site. To successfully reverse a vasectomy where this has occurred requires a more technically difficult repair known as a vasoepididymostomy. In this surgery, the vas above the vasectomy site is connected directly to the epididymis above the point of blockage, bypassing the vas below the vasectomy.
This procedure is one of the most technically demanding procedures in all of surgery, due to the extremely small and delicate nature of the epididymal tubule. The epididymal tubule is less than 1/10th the diameter of the vas, and has a mucosal wall only 2-3 cell layers thick. The procedure is performed by first visually inspecting the epididymis to determine the exact location of the obstruction. The thin outer layer of the epididymis is opened to expose the tubules, which are coiled together. A single tubule is identified, carefully teased away from the others, and opened along its side to check for the presence of sperm. The tubule is not completely cut, since it is difficult to determine which end is the correct one. If there is sperm present, the opening in the tubule is sewn to the mucosa of the vas with 10-0 nylon, after placing some larger sutures in the muscular layer of the vas to provide mechanical stability. This is called an end-to-side repair, and resembles a “T”. The number of mucosal sutures used depends on the surgeon's technique. A recent development, called the intussusception technique, uses only 3-4 sutures but provides excellent alignment by actually pulling the opening of the epididymal tubule into the lumen of the vas.