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Journal of Andrology, Vol. 25, No. 4, July/August 2004
Copyright © American Society of Andrology

The Use of URYX for Reversible Vasectomy in a Rabbit Model

CATHY K. NAUGHTON*, JONATHAN MYLES{dagger} AND ANTHONY J. THOMAS, JR.{ddagger}

From the * Division of Urological Surgery, Washington University School of Medicine, St. Louis, Missouri; and the {dagger} Department of Anatomic Pathology and {ddagger} Glickman Urological Institute, The Cleveland Clinic Foundation, Cleveland, Ohio.

Correspondence to: Cathy K. Naughton, Assistant Professor, Division of Urologic Surgery, Director of Male Infertility and Microsurgery, Washington University School of Medicine, Infertility and Reproductive Medicine Center, 4444 Forest Park Avenue, Suite 3100, St. Louis, MO 63108 (e-mail: naughtonc{at}msnotes.wustl.edu).
Received for publication December 2, 2003; accepted for publication March 2, 2004.

   Abstract
Top
 Abstract
Materials and Methods
 Results
 Discussion
 References
 
URYX is a biocompatible polymer of ethylene vinyl alcohol dissolved in a dimethyl sulfoxide (DMSO) carrier to allow injection of a very low-viscosity fluid into tissue. Once the material comes into contact with body tissue or fluid, the DMSO rapidly dissipates from the polymer, which results in a precipitate of a coherent solid mass. The purpose of the present study was to determine whether URYX can effectively occlude the vas deferens and whether patency can be restored by redissolving the URYX in vivo using the solvent DMSO. Eight male New Zealand White rabbits (age range, 25–41 weeks; mean age, 33.9 ± 7.5 weeks; mean weight, 4.0 ± 0.2 kg) were used in 2 experiments (E1 and E2). In E1, 3 rabbits underwent unilateral vasectomy, and the contralateral vas was injected with either 0.05 or 0.10 mL of URYX, to determine the amount of URYX required to cause obstruction. Two animals underwent bilateral vasectomy, to serve as controls. In E2, 3 animals underwent bilateral URYX injection and were compared with the bilateral vasectomy control rabbits used in E1. After 1 month of initial bilateral URYX treatment, all animals in E2 underwent attempted unilateral reversal with 1.5 mL of DMSO injected into 1 occluded vas deferens. Two end points were evaluated—a clinical end point assessed by semen analyses and a pathological end point assessed by histological analysis of treated tissues, to assess for safety. A 1.5-cm infrapubic incision was made to expose both vasa in anesthetized rabbits. The vasal injection of URYX was performed with a 30-gauge needle. Vasectomy was performed by excision of a 1-cm segment of the vas deferens and subsequent ligation with a 6-0 prolene suture. Semen was collected using an artificial vagina 2–3 times/wk before and 1 month later, after injection treatments and vasectomy. Manual sperm counts were performed. All animals were sacrificed, and tissues (distal vas, injection site, proximal vas, cauda epididymis, caput epididymis, and testis) were harvested and examined for the presence of URYX. The inflammatory response of the wall and adventitia of the vas deferens was given a score (0–15) based on the sum of grades (0 = none, 1 = mild, 2 = moderate, and 3 = severe) for the following categories: foreign body giant cell reaction, granulation tissue, lymphocytes, eosinophils, and scarring, as evaluated by a single pathologist (J.M.). Vasal injection with 0.05 mL of URYX was not sufficient to cause occlusion. Both animals injected with 0.1 mL of URYX were effectively occluded. The injection of occluded vasa with DMSO did not dissolve the URYX plug in the vas lumen. There was no significant difference in vasal inflammatory response scores between vasal units treated with URYX only and vasal units in the vasectomy model. Vasal units subjected to URYX followed by DMSO demonstrated greater inflammatory response scores than vasal units treated with URYX followed by normal saline, URYX alone, or vasectomy. Epididymal and testicular histology remained unaffected in all vasal units in E1. The vasal units in E2 subjected to URYX followed by normal saline showed no histological abnormalities of the epididymis and testis. However, those vasal units subjected to URYX followed by DMSO in E2 showed evidence of adhesions, necrosis, and degenerating cells in the epididymis and a focal foreign body giant cell reaction in the testis. The bilateral vasal injection of URYX can result in azoospermia in the rabbit model. Reversal with subsequent DMSO injection was not achieved. A minimal inflammatory response of the vas deferens was observed with URYX injection alone; however, DMSO following URYX injection resulted in increased vasal inflammation, in addition to epididymal and testicular changes.

     Key words: DMSO, vas deferens, testicle, epididymis


Vasectomy is a popular form of permanent male contraception worldwide because it is safe and cost-effective (Marquette et al, 1995; Trussel et al, 1995). More than 30 million couples worldwide are using vasectomy as birth control (Philp et al, 1984). In one European study, 6.5% of men who underwent voluntary contraceptive vasectomy requested reversal within 1 year (Engelmann et al, 1990). Presently, vasectomy reversal requires a surgical approximation of the two ends of the disrupted vas deferens (vasovasotomy) or anastomosis of the vas to the more proximal epididymis (vasoepididymostomy). Pregnancy rates after vasectomy reversal range from 30%–76%, depending on the time between vasectomy and reversal and the age of the female partner (Silber, 1989; Belker et al, 1991; Sharlip, 1993; Fuchs and Burt, 2002). These surgical procedures can be both invasive and costly.

The concept of an intravasal method for occlusion with the option of subsequent reversal is not new. Earlier attempts to develop reversible occlusive technology focused on rigid and flexible prosthetic devices (Brueschke et al, 1974a,b,c, 1975, 1979, 1980). These devices require surgical implantation, cause vasal wall erosion, and are unable to reliably occlude the vas deferens. More recent technologies have focused on the less invasive percutaneous intravasal delivery of materials, including silicone rubber, an elastomeric-hydrogel matrix plug, and medical polyurethane (Carroll et al, 1993; Soebadi et al, 1995). Although these techniques provide relatively good occlusion, the materials demonstrate significant histological effects on tissues (Chen et al, 1996). Furthermore, the reversibility of these agents is unknown. A recent report on styrene maleic anhydride used as an occlusive agent and dimethyl sulfoxide (DMSO) as a reversal agent was studied in langar monkeys (Lohiya et al, 2000). Vasal occlusion causing uniform azoospermia required 2 injections, and reversal required a relatively labor-intensive technique (palpation, percutaneous electrical stimulation, forced vibratory movement, suprapubic percussion, and per-rectal digital massage of the vas segments).

Efforts to develop less invasive techniques for "permanent" vasectomy with the option of easy "reversibility" has led to the possible application of a chemical occlusive agent, URYX (Genyx Medical, Inc, Aliso Viejo, Calif). URYX is an expansion of the product EMBOLYX (Micro Therapeutics, Inc, San Clemente, Calif), a biocompatible polymer of ethylene vinyl alcohol. This polymer is dissolved in a DMSO carrier to allow the injection of a very low viscosity fluid into tissues or a vessel. Once the dissolved material comes into contact with body tissue or fluids, the DMSO rapidly dissipates from the polymer, which results in a precipitate of a coherent solid mass (Figure 1). Success has been achieved with EMBOLYX (Micro Therapeutics) for the interventional embolization of vascular malformations in swine rete mirabile, for tumor control by selective arterial occlusion in a rabbit model, and in human clinical cases of brain arteriovenous malformations (Murayama et al, 1998; Chaloupka et al, 1999; Nahser et al, 1999; Wright et al, 1999). URYX has been successfully used for selective fallopian tube occlusion in a rabbit model. Pregnancy was subsequently confirmed in the nonembolized fallopian tube in 9 of 10 rabbits receptive to breeding. No pregnancies were observed on the embolized tubes. There was no gross evidence of inflammation, adhesions, or URYX in the peritoneum in any animal (Abdala et al, 2001).



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  		Figure 1. URYX is a biocompatible polymer of ethylene vinyl alcohol dissolved in a dimethyl sulfoxide (DMSO) carrier, which enables the polymer to be delivered as a low-viscosity fluid (a). Once the material contacts body tissue or fluid, the DMSO rapidly dissipates from the polymer, resulting in a precipitate of a coherent solid mass (b, c). A URYX plug may subsequently be redissolved into its liquid state with DMSO (d).

 

The presence of URYX grossly causes pigmentation within the fallopian tubes but, histologically, there is only mild to moderate inflammation and fibrosis (Abdala et al, 2001). DMSO alone causes a transient reduction in renal artery blood flow when it is injected intra-arterially, but it does not cause obstruction of flow (Murayama et al, 1998). Histologically, kidneys exposed to DMSO alone demonstrate moderate to marked multifocal acute mural necrosis in larger blood vessels (Wright et al, 1999). When DMSO is rapidly injected (5 seconds) into the swine rete mirabile, macroscopic examination of the brain shows acute subarachnoid hemorrhage around the brain stem. Microscopically, there is extensive transmural fi-brinoid necrosis of the vascular walls and rete vessel occlusion by faintly eosinophilic material containing nuclear debris. In contrast, in a 15-second slower injection of DMSO, only focal mild inflammation is observed (Murayama et al, 1998). The safety and histological effects of URYX and DMSO to the vas deferens, epididymis, and testis are unknown. The purpose of the present study was to determine, in a rabbit model, whether URYX is safe and effective in causing occlusion of the vas deferens and whether subsequent patency can be achieved by dissolving URYX using its organic solvent, DMSO.


   Materials and Methods
Top
 Abstract
 Materials and Methods
Results
 Discussion
 References
 
The Cleveland Clinic Foundation Animal Research Committee approved all experiments involving animals. Eight male New Zealand White rabbits (age range, 25–41 weeks, mean age, 33.9 ± 7.5 weeks; mean weight, 4.0 ± 0.2 kg) were used in 2 experiments (E1 and E2) to address 2 questions. (1) How much URYX is required to cause vasal obstruction? (2) Can patency follow vasal occlusion caused by a bilateral injection of 0.1 mL URYX using DMSO? Three rabbits underwent unilateral vasectomy, and the contralateral vas deferens was injected with either 0.05 mL (n = 1) or 0.10 mL (n = 2) of URYX. Semen analyses were performed before treatment and then biweekly after the procedure for 1 month, at which time the animals were sacrificed and tissues harvested for pathologic analysis. Two animals underwent bilateral vasectomy to serve as controls. To answer the second question, 3 animals underwent a bilateral injection of 0.1 mL of URYX with successful bilateral vasal occlusion at 1 month after injection, as demonstrated by azoospermia on semen analysis. One month after bilateral vasal occlusion, all animals underwent a unilateral injection of 1.5 mL of DMSO and a contralateral control injection of 1.5 mL normal saline (NS). All animals underwent biweekly semen analyses and were sacrificed 1 month after the attempted unilateral reversal with DMSO. In both experiments, two end points were assessed: a clinical end point assessed by semen analyses and a pathologic end point assessed by the histological evaluation of vas deferens, epididymis, and testis.

Vasal Surgery

The bilateral vasa were exposed in a similar fashion in vasectomy, URYX injection, and DMSO reversal. All procedures were performed by a single surgeon (C.K.N.) who used 2.5x magnification loops. Animals were anesthetized with an intramuscular injection of xylazine (4 mg/kg) and ketamine (50 mg/kg) and a subcutaneous injection of acepromazine (1.0 mg/kg). A 1-cm suprapubic transverse incision was made in the midline one fingerbreadth cephalad to the pubic symphysis. The spermatic cords were brought up through the incision and isolated. The cremasteric fascia was incised in a longitudinal fashion, and the vas deferens was isolated with its blood supply, using a towel clip.

For those animals undergoing vasectomy, a 1-cm segment of the vas deferens was excised, the lumen was cauterized, and the distal and proximal ends were ligated with 6-0 Prolene sutures. The excised segment of vas deferens was placed in formalin and processed for histological confirmation.

For those animals undergoing URYX injection, the vas deferens was cannulated with a 30-gauge lymphangiographic needle (003401; Cook Urological Inc, Spencer, Ind), which had been preflushed with DMSO, just distal to the convoluted vas deferens. Vortexed URYX, which contained micronized tantalum powder added to the polymer/solvent mixture to obtain radiopacity, was slowly injected (0.05 mL/30 seconds) intravasally. The URYX was allowed to solidify for 1 minute (Figure 2). The needle was removed, and the vasal muscularis at the site of injection was tagged with a 6-0 Prolene suture. Intraoperative fluoroscopy was used to document successful URYX injections (Figure 3a).



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  		Figure 2. An infrapubic transverse skin incision allows easy access to both vasa (a). A 30-gauge lymphangiographic needle is placed into the lumen of the isolated vas deferens (b). An intravasal URYX plug is created (c).

 


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  		Figure 3. An intraoperative fluoroscopic image of a 0.1-mL bilateral vasal injection with URYX. Micronized tantalum powder added to the polymer/solvent mixture allows for radiopacity (a). One month after the bilateral vasal URYX injection and azoospermia confirmed by semen analyses, the migration of URYX into the left ampulla was noted (b). No significant change in the URYX plug position in the same animal 1 month after a right vasal injection of 1.5 mL of dimethyl sulfoxide and a left vasal injection of 1.5 mL of normal saline control and biweekly ejaculations (c).

 

For animals undergoing DMSO reversal, intraoperative fluoroscopy was used to document the status of the URYX plug after 1 month of biweekly ejaculations (Figure 3b). The vas deferens was exposed, and the site of the previously placed Prolene suture was isolated. The DMSO preflushed 30-gauge lymphangiographic needle was used to cannulate the lumen of the vas deferens and to inject 1.5 mL of DMSO intravasally proximal to the Prolene suture. After all procedures, the skin incision was closed using interrupted 4-0 nylon sutures. The treatment of vasal units in E1 and E2 is shown in Table 1.


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  		Table 1. Treatment of vasal units in experiments 1 and 2 (E1 and E2)
 

Semen Analyses

Pretreatment and postprocedure semen was collected biweekly using a "homemade" artificial vagina described elsewhere (Naughton et al, 2003). Collected ejaculates were analyzed for volume, total sperm count, sperm density, and motility. Azoospermia was confirmed by examining 20 fields of a stained smear pellet at 200x magnification after centrifugation at 800 x g for 7 minutes. All semen analyses parameters were determined manually by one investigator (C.K.N.).

Histological Analyses

Animals were sacrificed 1 month after the vasectomy and URYX-only injection procedures (E1). Those animals that underwent subsequent DMSO reversal attempts were sacrificed 1 month after the DMSO injection (E2). All animals were sacrificed with an intravenous overdose of Beuthanasia-D (Schering-Plough Animal Health, Kenilworth, NJ). Testicles, epididymides, vasa, and vasal ampulla were removed en bloc and placed in formalin for histological examination. The distal vas, injection site, proximal vas, cauda epididymis, caput epididymis, and testis were each examined separately in paraffin blocks. Blocks were sectioned at 6 microns and stained with hematoxylin and eosin. Tissues were examined for the presence of URYX and assessed for signs of inflammation. The inflammatory response of the wall and adventitia of the vas deferens was given a score (0–15) that was based on the sum of semiquantitative grades (0 = none, 1 = mild, 2 = moderate, and 3 = severe) for the following categories: foreign body giant cell reaction, granulation tissue, lymphocytes, eosinophils, and scarring. Inflammatory response scores of 1–5, 6–10, and 11–15 corresponded to mild, moderate, and severe changes, respectively. The histological evaluation of tissues was performed blindly by a single pathologist (J.M.).


   Results
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 Abstract
 Materials and Methods
 Results
Discussion
 References
 
Clinical End Points

An injection of 0.10 mL of URYX caused vasal obstruction. Vasal injection with 0.05 mL of URYX was not sufficient to cause occlusion; however, the vasa of the two animals injected with 0.1 mL of URYX were effectively occluded, as demonstrated by the subsequent absence of sperm in their ejaculates. Three animals in the E2 group underwent a bilateral injection with 0.10 mL of URYX. Three to five ejaculations were required to achieve azoospermia. One month after the URYX injection, just before the animals were sacrificed, fluoroscopic imaging demonstrated the migration of the URYX plug distally toward the vasal ampulla (Figure 3b). The injection of 1.5 mL of DMSO did not reverse URYX-induced azoospermia. The unilateral injection of occluded vasa with DMSO did not dissolve the URYX pellet in the vas lumen. All 3 animals demonstrated persistent azoospermia 1 month after the injection of DMSO (Table 2).


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  		Table 2. Pretreatment and postprocedure semen parameters
 

Pathology End Points

Before animals were sacrificed and their tissues subsequently harvested, 3 vasal units were subjected to an injection of URYX only, 7 vasal units were subjected to vasectomy, 3 vasal units were subjected to injections of URYX then NS, and 3 vasal units were subjected to injections of URYX then DMSO (Table 3). There was no significant difference in vasal inflammatory response scores between vasal units treated with URYX only, compared with vasal units that underwent vasectomy. A mild inflammatory response was observed in the vas deferens of vasal units treated with URYX alone or with vasectomy. The inflammatory changes in the vasectomy units were found more in the distal and proximal vas adventitia, when they were present. Vasitis nodosum was observed in 4 of 7 vasal units after vasectomy. This was characterized by an obliterated vasal lumen and moderate vasal adventitia inflammation (Figure 4c). The other 3 vasal units that had undergone vasectomy did not contain the area of vasal excision. In contrast, the vasal units subjected to injection with URYX only did not show proximal vasal inflammatory changes, but these changes were observed at the injection site and distal vas. Vasal units subjected to injection with URYX followed by DMSO demonstrated the greatest inflammatory response scores, compared with vasal units treated with URYX followed by NS, URYX alone, or vasectomy alone. A moderate inflammatory response was particularly evident in the vasal lumen at the injection site (Figure 4a–j).


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  		Table 3. Inflammatory response scores of vasal units after treatment
 


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  		Figure 4. Hematoxylin and eosin staining of normal vas deferens resected at the time of vasectomy (a). Mild inflammation was noted in the contralateral vas deferens of the same animal injected with 0.1 mL of URYX at the injection site (b). Vasitis nodosum was seen in vasal units that underwent vasectomy (c). Muscular wall disruption with severe inflammation was noted when URYX was technically misplaced outside the vasal lumen (d). Vasal units injected with URYX followed by dimethyl sulfoxide (DMSO) (e) demonstrated greater inflammatory response scores compared with vasal units injected with URYX followed by normal saline (h). Foreign body reaction (3+), granulation tissue (3+), lymphocytes (1+), and scarring (1+) were observed in the lumen of vasal units injected with URYX followed by DMSO (f). The adventitia also showed a foreign body reaction (2+) and granulation tissue (1+) (g). In contrast, vasal unit injection with URYX followed by normal saline resulted in only mild inflammatory changes in the vasal lumen and adventitia (e, f). Animals subjected to intravasal injection with URYX followed by DMSO showed evidence of adhesions, necrosis, and degenerating cells in the epididymis (m) or foreign body giant cell reaction in the testis (n). In contrast, the vasal units in E2 injected with URYX followed by normal saline showed no histological abnormalities of the epididymis and testis (k, l), comparable to the epididymides and testes of control animals that underwent bilateral vasectomy only. Histological correlation of URYX plug migration into the left vasal ampulla 1 month after URYX injection in the unilateral left vas deferens (p) that was not seen in vasal ampulla of a control animal that underwent bilateral vasectomy (o).

 

Epididymal and testicular histology remained unaffected in all vasal units from the E1 group. Those vasal units subjected to injection with URYX followed by DMSO in the E2 group, however, showed evidence of adhesions, necrosis, and degenerating cells in the epididymis and foreign body giant cell reaction in the testis (Figure 4m, n). In contrast, the vasal units in the E2 group subjected to injection with URYX followed by NS showed no histological abnormalities of the epididymis and testis (Figure 4k, l), comparable to the epididymides and testes of control animals that underwent bilateral vasectomy only.


   Discussion
Top
 Abstract
 Materials and Methods
 Results
 Discussion
References
 
The purpose of the present study was to address 2 questions: 1) Is URYX effective in causing vasal obstruction in the rabbit model? 2) Is DMSO effective in reversing URYX occlusion? Additionally, we wanted to assess the safety and histological effects of URYX and DMSO on the vas deferens, epididymis, and testis.

Our initial experiments were aimed at determining how much URYX is required for complete vasal occlusion. We determined that the unilateral injection of 0.1 mL of URYX and contralateral vasectomy is sufficient to cause azoospermia after 2 to 3 ejaculations, and this persisted up to 1 month. We then injected 0.1 mL of URYX bilaterally and determined that azoospermia was achieved within 1 to 3 ejaculations, similar to control animals that underwent bilateral vasectomy (Table 2). After 1 month of biweekly ejaculations, however, the URYX plug was found to have migrated distally towards the ampulla. This was clearly demonstrated by fluoroscopic images obtained before the animals were sacrificed and histologically by the presence of URYX material at the ampulla instead of the straight portion of the vas deferens, where it was initially injected (Figure 4p). Because the longest interval between URYX injection and any animal's death was only 2 months, the long-term effects of the injected material are not known. Furthermore, the ability to reliably reverse vasal occlusion using DMSO when the location of the plug varies is suspect. Histologically, URYX alone did not appear to cause a significant tissue reaction. However, the histological consequences of the technical misplacement of URYX into the vasal muscularis instead of the vasal lumen demonstrated scarring (Figure 4d).

We were not able to demonstrate any reversible effect on URYX by DMSO in our study. We believe that the most likely reason is the low contact time of DMSO with the URYX plug. Completely submerging a URYX plug into a solution of DMSO will result in the liquefaction of the plug (Figure 1d); however, the URYX plug in a lumen may not have been exposed to enough DMSO or have had enough contact time with the solvent to cause the URYX plug to dissolve. Additionally, the vasal administration of DMSO results in significant vasal, epididymal, and testicular inflammatory changes (Figure 4). We believe that these effects were caused mainly by DMSO, given that no epididymal or testicular histological abnormalities were found in animals injected with URYX alone. Our data suggest that the repeated vasal injections may have contributed to the increased inflammation seen in injected vasal units URYX and NS, compared with URYX alone. A strong conclusion regarding the histological end points is difficult to determine because of the small number of animals used and the variability of inflammatory response among the animals (Table 3). One animal (36) died 7 days after the injections with DMSO and NS. This animal demonstrated decreased feeding ~2–3 days after anesthesia for the reversal (DMSO) procedure. We postulate that the death of this animal was related to anesthetic/sedative effects rather than to the administration of DMSO. Because the exact day of death was not known, we elected not to harvest tissue from this animal, because the interpretation of any tissue histology would have been affected by the unknown interval of ischemia.

The clinical utility of studying suitable materials for vasal injection is to find a truly reversible vasectomy. The ideal reversible vasectomy would be able to reliably and reproducibly cause vasal obstruction and azoospermia but then to, reliably and reproducibly, easily enable vasal patency to be restored, if desired. At present, vasectomy is a common and reliable method of contraception. A certain percentage of men who undergo a vasectomy will request a reversal. A couple's options for conceiving their own biological child after vasectomy are vasectomy reversal or assisted reproductive techniques, both of which are costly and not always successful.

We have demonstrated, in a rabbit model, that injection with URYX may have the potential for permanent vasal occlusion without significant histological effects in the vas deferens. This material will require more long-term studies in vitro and in vivo before its application to humans. A hurdle in using this material for reversible vasectomy is that the DMSO injected into the vasal lumen will only make contact with a small proximal end of the URYX plug. In vitro testing to explore methods that would increase the exposed surface area and/or contact time of the URYX plug to DMSO is important. Preliminary experiments may be performed using a silicone tube as an ex vivo vas deferens model to determine the time interval and amount of DMSO required to completely dissolve a defined length of URYX plug. This system may be used to determine how the required amount of DMSO will vary as a function of URYX plug length. Future animal studies may require subsequent testing on another animal model, such as the dog, which have vasa more similar to humans than those of the rabbit. Studies in animal models should focus on the significance of URYX plug migration and its consequences on long-term ejaculated semen parameters. The application in humans will, in part, depend on the technical ability of successful intravasal cannulation. On the basis of our data, DMSO is not effective in reversing occlusion created by a URYX plug in the vasal lumen, and it does not appear to be safe for vasal injection in the rabbit model.


   Footnotes
 
? Supported by Genyx Medical, Inc. Back


   References
Top
 Abstract
 Materials and Methods
 Results
 Discussion
 References
 
Abdala N, Levitin A, Dawson A, Maffra R Jr, Munoz-Ramirez H, Godec K, Dolmatch BL. Use of ethylene vinyl alcohol copolymer for tubal sterilization by selective catheterization in rabbits. J Vasc Interv Radiol. 2001;12: 979 -984.[Medline]

Belker AM, Thomas AJ Jr, Fuchs EF, Konnak JW, Sharlip ID. Results of 1,469 microsurgical vasectomy reversals by the Vasovasostomy Study Group. J Urol. 1991;145: 505 -511.[Medline]

Brueschke EE, Burns M, Maness JH, Wingfield JR, Mayerhofer K, Zaneveld LJ. Development of a reversible vas deferens occlusive device. I. Anatomical size of the human and dog vas deferens. Fertil Steril. 1974a;25: 659 -672.[Medline]

Brueschke EE, Kaleckas RA, Wingfield JR, Welsh TJ, Zaneveld LJ. Development of a reversible vas deferens occlusion device. VII. Physical and microscopic observations after long-term implantation of flexible prosthetic devices. Fertil Steril. 1980; 33: 167 -78.[Medline]

Brueschke EE, Wingfield JR, Burns M, Zaneveld JD. Development of a reversible vas deferens occlusive device. II. Effect of bilateral and unilateral vasectomy on semen characteristics in the dog. Fertil Steril. 1974b;25: 673 -686.[Medline]

Brueschke EE, Zaneveld LJ, Kaleckas RA, Wingfield JR. Development of a reversible vas deferens occlusive device. VI. Long-term evaluation of flexible prosthetic devices. Fertil Steril. 1979; 31: 575 -86.[Medline]

Brueschke EE, Zaneveld LJ, Rodzen R, Berns D. Development of a reversible vas deferens occlusive device. 3. Morphology of the human and dog vas deferens: a study with the scanning electron microscope. Fertil Steril. 1974c;25: 687 -702.[Medline]

Brueschke EE, Zaneveld LJ, Rodzen R, Mayerhoffer K, Burns M, Wingfield JR. Development of reversible vas deferens occlusive device. V. Flexible prosthetic devices. Fertil Steril. 1975; 26: 40 -52.[Medline]

Carroll JC, Schwaitzberg SD, Ucci AA Jr, Schlesinger RM, Lauritzen D, Sant GR. New matrix material for potential use in "reversible" vasectomy: preliminary animal biocompatibility studies. Urology 1993;41: 34 -37.[Medline]

Chaloupka JC, Huddle DC, Alderman J, Fink S, Hammond R, Vinters HV. A reexamination of the angiotoxicity of superselective injection of DMSO in the swine rete embolization model. AJNR Am J Neuroradiol. 1999;20: 401 -410.[Abstract/Free Full Text]

Chen Z, Gu Y, Liang X, Shen L, Zou W. Morphological observations of vas deferens occlusion by the percutaneous injection of medical polyurethane. Contraception 1996; 53: 275 -279.[Medline]

Engelmann UH, Schramek P, Tomamichel G, Deindl F, Senge T. Vasectomy reversal in central Europe: results of questionnaire of urologists in Austria, Germany and Switzerland. J Urol. 1990; 143: 64 -67.[Medline]

Fuchs EF, Burt RA. Vasectomy reversal performed 15 years or more after vasectomy: correlation of pregnancy outcome with partner age and with pregnancy results of in vitro fertilization with intracytoplasmic sperm injection. Fertil Steril. 2002; 77: 516 -519.[Medline]

Lohiya NK, Manivannan B, Mishra PK. Repeated vas occlusion and noninvasive reversal with styrene maleic anhydride for male contraception in langur monkeys. Int J Androl. 2000; 23: 36 -42.[Medline]

Marquette CM, Koonin LM, Antarsh L, Gargiullo PM, Smith JC. Vasectomy in the United States, 1991. Am J Public Health 1995;85: 644 -649.[Abstract/Free Full Text]

Murayama Y, Vinuela F, Ulhoa A, Akiba Y, Duckwiler GR, Gobin YP, Vinters HV, Greff RJ. Nonadhesive liquid embolic agent for cerebral arteriovenous malformations: preliminary histopathological studies in swine rete mirabile. Neurosurgery 1998; 43: 1164 -1175.[Medline]

Nahser HC, Kühne D, Feiden W. Preliminary report on the use of Onyx liquid embolic system for the treatment of brain arteriovenous malformations. Irvine, Calif: Micro Therapeutics Inc; 1999 .

Naughton CK, Nelson DR, Thomas AJ Jr. Development of an inexpensive artificial vagina for semen collection from rabbits. J Androl. 2003;24: 712 -715.[Abstract/Free Full Text]

Philp T, Guillebaud J, Budd D. Complications of vasectomy: review of 16,000 patients. Br J Urol. 1984; 56: 745 -748.[Medline]

Sharlip ID. What is the best pregnancy rate that may be expected from vasectomy reversal? J Urol. 1993; 149: 1469 -1471.[Medline]

Silber SJ. Pregnancy after vasovasostomy for vasectomy reversal: a study of factors affecting long-term return of fertility in 282 patients followed for 10 years. Hum Reprod. 1989; 4: 318 -322.[Abstract/Free Full Text]

Soebadi DM, Gardjito W, Mensink HJ. Intravasal injection of formed-inplace medical grade silicone rubber for vas occlusion. Int J Androl. 1995;18(suppl 1): 45 -52.

Trussel J, Levesque JA, Koenig JD, et al. The economic value of contraception: a comparison of 15 methods. Am J Public Health 1995;85: 494 -503.[Abstract/Free Full Text]

Wright KC, Greff RJ, Price RE. Experimental evaluation of cellulose acetate NF and ethylene-vinyl alcohol copolymer for selective arterial embolization. J Vasc Interv Radiol. 1999; 10: 1207 -1218.[Medline]





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