Biomaterials/sealants

Fibrin glue (FG) has been used in experimental models and in one clinical study in urologic microsurgery. Fibrin sealant, as used in vasovasostomy (VV) and VE, stimulates the coagulation cascade and produces a fibrin seal around the anastomosis. Fibrinogen, when mixed with thrombin and calcium, is converted to fibrin monomer. The fibrin monomer is converted to a stable cross-linked fibrin polymer . The rationale for using sealants such as FG is to decrease operative time and to simplify the procedure without compromising success rates.

Several investigators have used FG for VV in animals and reported patency rates of 90% or greater. In some instances the patency rate was similar to standard microsurgical anastomoses. Silverstein and Mellinger described a FG-assisted anastomotic technique using only two transmural sutures and FG. The operative time was shorter, and the patency rate for the FG-assisted anastomosis (90%) was comparable to the formal two-layer technique (83%). It should be noted, however, that the patency rate of 83% for microsurgical VV is lower than most reported series. Vankemmel and colleagues described a FG VV with three transmural sutures and reported a patency rate of 92%, similar to the 85% patency rate for the animals in which conventional modified one-layer anastomoses were used.

The major concern about the use of FG in clinical practice is the potential contact of the glue with the vasal lumen and resultant obstruction. Also, because FG is derived from pooled plasma, there has been concern about transmission of viral disease . Niederberger and colleagues demonstrated that FG could be prepared from a single human source and that a vasovasal anastomosis with FG could be performed with patency comparable to a standard microsurgical anastomosis in a rabbit model.

Schiff and colleagues tested a biomaterial sealant and a biomaterial wrap (either derived from amniotic membranes or an acellular dermal matrix) for VV in a rat model. VV was performed using one of five different techniques: (1) standard multilayer VV; (2) the control technique using three full-thickness sutures; (3) three full-thickness sutures plus biomaterial wrap; (4) three full-thickness sutures plus biomaterial wrap and copolymer sealant; and (5) three full-thickness sutures plus copolymer sealant. Operative times were shorter for methods 2 through 5, and patency for group 3 was comparable to that of multilayer VV. The group hypothesized that the results in the sealant groups were inferior because an air-assisted delivery system may have forced sealant into the lumen and caused obstruction.

Ho and colleagues performed the first study with FG for VV in humans using three transmural 9-0 sutures. They reported an 85% patency rate in patients with sufficient follow-up and a 96% patency rate when sperm was present in the vasal fluid. The definition of patency was not clearly stated, but the median sperm concentration at 9 and 12 months was greater than 50 million/mL. The mean follow-up was 6.2 months, the mean obstructive interval was 7.9 years, and the mean operative time was 79 minutes. VE was not performed in this study, and, as expected, patency declined with increasing obstructive interval. The pregnancy rate was 23% (9 of 39) with a mean follow-up of 6.2 months. Because the follow-up was short, the frequency of secondary azoospermia is not known. This technique could represent a viable alternative for the surgeon who performs only an occasional vasectomy reversal.

The use of FG also has been investigated for VE. Shekarriz and colleagues described a new VE technique using FG and compared it with conventional end-to-side VE in a rat model. The conventional end-to-side two-layer VE was performed with 11-0 and 10-0 nylon sutures, and the FG-assisted anastomosis used an invagination technique, using two 11-0 nylon sutures for the inner layer and 10-0 nylon for the outer layer. Patency was 79% in the FG-assisted VE group and 63% in the conventional end-to-side VE group ( P = .29). Operative time was shorter in the FG-assisted group than in the standard end-to-side group (15.3 ± 1.3 versus 33.2 ± 4.2 minutes, respectively; P < .001).

Although FG studies are encouraging, this technique has not been adopted for clinical practice.

Laser soldering

Like sealants, lasers have been used in microsurgery in animal models to improve tissue bonding and limit anastomotic leakage. Seaman and colleagues compared a diode laser–assisted anastomosis with a conventional sutured microsurgical anastomosis for VV and VE in rats. Laser soldering (ie, laser tissue welding using a protein solder) was used for the experimental group. In this technique, the laser was used to activate a protein solder composed of albumin, sodium hyaluronate, and indocyanine green dye. Operative times were shorter for the laser-assisted group, and the patency rates were similar for both groups. Laser-assisted VV and conventional VV patency rates were 90% and 80%, respectively. Laser-assisted VE and conventional VE patency rates were 82% and 73%, respectively.

Mingin and Ditrolio described laser-assisted VV using an argon laser and an albumin protein solder in five men, two of whom were undergoing repeat VV after a failed microsurgical VV. The investigators placed two intraluminal 9-0 nylon sutures followed by laser welding of a 10% albumisol solution around the anastomotic site. Two 5-0 polyglactin sutures were placed in the perivasal tissues. All five men experienced patency with sperm concentrations of at least 17.5 M/mL, and three of the five established a pregnancy. Total operative times ranged from 37 to 60 minutes.

Shanberg and colleagues reported their results with carbon dioxide laser–assisted VV in 32 patients. For obstructive intervals shorter than 10 years, the patency rate was 95%, but the pregnancy rate was only 35%. For obstructive intervals longer than 10 years, the patency and pregnancy rates were 36% and 9%, respectively. No explanation was provided for the marked decrease in success rates after 10 years’ obstruction. The authors concluded that the procedure was easier to perform than conventional microsurgical techniques and that results were comparable. The latter point could be disputed, because the pregnancy rate of 35% for obstructive intervals shorter than 10 years is inferior to most published series.

Laser soldering

Like sealants, lasers have been used in microsurgery in animal models to improve tissue bonding and limit anastomotic leakage. Seaman and colleagues compared a diode laser–assisted anastomosis with a conventional sutured microsurgical anastomosis for VV and VE in rats. Laser soldering (ie, laser tissue welding using a protein solder) was used for the experimental group. In this technique, the laser was used to activate a protein solder composed of albumin, sodium hyaluronate, and indocyanine green dye. Operative times were shorter for the laser-assisted group, and the patency rates were similar for both groups. Laser-assisted VV and conventional VV patency rates were 90% and 80%, respectively. Laser-assisted VE and conventional VE patency rates were 82% and 73%, respectively.

Mingin and Ditrolio described laser-assisted VV using an argon laser and an albumin protein solder in five men, two of whom were undergoing repeat VV after a failed microsurgical VV. The investigators placed two intraluminal 9-0 nylon sutures followed by laser welding of a 10% albumisol solution around the anastomotic site. Two 5-0 polyglactin sutures were placed in the perivasal tissues. All five men experienced patency with sperm concentrations of at least 17.5 M/mL, and three of the five established a pregnancy. Total operative times ranged from 37 to 60 minutes.

Shanberg and colleagues reported their results with carbon dioxide laser–assisted VV in 32 patients. For obstructive intervals shorter than 10 years, the patency rate was 95%, but the pregnancy rate was only 35%. For obstructive intervals longer than 10 years, the patency and pregnancy rates were 36% and 9%, respectively. No explanation was provided for the marked decrease in success rates after 10 years’ obstruction. The authors concluded that the procedure was easier to perform than conventional microsurgical techniques and that results were comparable. The latter point could be disputed, because the pregnancy rate of 35% for obstructive intervals shorter than 10 years is inferior to most published series.

Stents

Stents are used widely in urinary tract reconstruction, so it is not surprising that investigators have explored their use for microsurgical reconstructive procedures. Absorbable and nonabsorbable stents have been used in clinical studies and animal models, respectively, to improve the alignment of the two vasal ends, to make the procedure easier to perform, and potentially to improve results.

Rothman and colleagues conducted a randomized trial comparing a conventional two-layer microsurgical closure with a modified anastomosis using an absorbable polyglycolic acid stent without intraluminal sutures. The modified anastomosis was performed with the intraluminal stent and 9-0 nylon sutures placed in the muscularis. The patency rate was lower for the stented group than for the conventional anastomosis group, but the difference did not reach statistical significance (81% versus 89.6%, respectively; P = .2). The operative time was significantly shorter in the stented group (118.1 ± 32.3 minutes versus 137.5 ± 24.9 minutes; P < .001), but the pregnancy rate for the stented group was inferior to that for the conventional two-layer closure (22% versus 51%; P = .002). The total motile sperm counts for the two groups were similar. The authors concluded that patency and pregnancy rates were inferior in the stented group and did not recommend use of the absorbable stent used in this study .

Vrijhof and colleagues investigated a nonabsorbable polymeric stent for VV in rabbits. The animals were assigned randomly to either a one-layer anastomotic technique with interrupted 8-0 polypropylene suture or a stented anastomosis with three polypropylene sutures (8-0) placed in the muscularis over the stent. All the vasa were patent at 39 to 47 weeks. Inflammatory reaction was seen around the stent, but more animals in the unstented group had partial obstructions. Total sperm count was higher in the stented group ( P = .05). The authors concluded that this type of stent warrants more study with application in human studies. Although the use of stents is intriguing, they have not found their way into clinical practice. One potential difficulty with stents is disparate lumen diameters of the testicular and abdominal ends.