| BACKGROUD AND OBJECTIVEUreteroneocystostomy is a frequently performed procedure to manage distal ureteralstenosis and vesicoureteral reflux. It is also a major method of surgical reconstruction ofurinary tract continuity in renal transplantation. Today, a variety of surgical techniques areavailable, among which the extravesicalureteroneocystostomytechnique (Lich-Gregoir methods) with their modifications, is probably the mostpopular. Despite improved surgical technique and immunosuppressive agents, urologicalcomplications still occur and account for significant morbidity and graft failure. The mostcommon urological complications are ureteral obstruction and leakage of theureteroneocystostomy. Although the use of a splint through the ureterocystostomy willresult in a significantly lower urological complication rate, routine splinting is known toincrease the number of urinary tract infections that can be graft and life-threatening.Meanwhile, dislodgement of the stent results in injury or obstruction, and removal of thisdevice requires an invasive procedure.Recently, we have utilized the titanium ring-pinstapler to reconstruct artery in clinical renal transplantation . We showed that the ring-pinsystem can be safely and easily applied to major artery reconstruction with a high patencyrates. The mechanical technique results in less bleed leakage and artery stenosis with aneverting anastomosis, providing a viable alternative to manual suturing. The purpose of thisexperiment was to compare ring-pin stapler with conventional sutures with routine uretericstenting and without routine ureteric stenting in vesicoureteral anastomosis, with specialfocus on anastomosis time, ureteral obstruction, urine leakage, vesicoureteral reflux, andstone formation during a follow-up period of 3 months. To our knowledge, this is the firstreport of a sutureless technique without routine ureteric stenting for extravesical ureteroneocystostomy.MATERIALS AND METHODS:Eighteen mongrel male dogs weighing 10 to 19 kg (mean, 16.5 kg) were used in our experiment. The animals were randomly divided into three groups of 9. Group I received non-sutured ureteroneocystostomy using the titanium ring pin stapler, and Group II received hand-sutured without routine ureteric stenting ureteroneocystostomy using Vicryl 5-0 adsorbable sutures, and GroupШreceived hand-sutured with routine ureteric stenting ureteroneocystostomy using 5-0 adsorbable Vicryl sutures. All experiments were performed according to our Institutional Guidelines on Animal Care and Use. The principles of laboratory animal care were followed.Preoperative ManagementAnimals were not fed anything but water 24 h before the operation. The introduction of anesthesia was started via the intraperitoneal injection of the sterilized pentobarbital sodium (30mg/kg). The dog was then placed in supine position and intubated. An intravenous infusion of atropin (0.01 mg/kg) was performed, and the anesthesia was continued with intravenous administration of pentobarbital sodium. All dogs were subjected to color duplex ultrasonography to exclude congenital anomalies of urinary system before the start of the experiments. The vesical pressure was nullified by insertion of a urethral catheter (6-8 F). For infection prophylaxis, a dose of ceftriaxone sodium (2 g) was administered intravenously at the beginning of surgery.Surgical TechniquesA midline incision was made to expose the urinary bladder. The random ureter was ligated and divided at its most distal part. The outer diameter of ureter was measured with a caliper. Mechanical dilation of the ureter end with a mosquito clamp was performed to make the ureter mouth larger when it was necessary. Before ureterovesical anastomsis, the distal ureter was spatulated and a 3 to 4cm long myotomy was made in the posterior-lateral bladder wall at a point 2 cm above the site of the normal ureterovesical junction.Non-sutured ureteroneocystostomyThe anastomotic process of bladder mucosa and distal ureter with titanium ring pin staplers was performed . Firstly,the bladder mucosa in the distal edge of the myotomy was clawed with a crochet-hook and stretched up to form a conus about 1cm high. The mucosa conus was then passed through a titanium ring, which was mounted in a ring holder. Secondly, the circular cone was cut open and its edge was everted and impaled on the small pins. A similar procedure was performed on the ureter end. Thirdly, the two ring holders were brought together by passing the pins of the two rings through the everted edges of both of ureter and bladder mucosa to be included in the anastomosis with each other. The ring holders were then compressed with the crushing clamp to make the ureter and bladder mucosa unite tightly. Finally, the assembled rings together with the anastomosis were released as the ring holders were simultaneously unlocked. The anastomosis was secured by interlocking the small pins, which were bent by clamping when the two rings were brought together and compressed. The two edges of the muscle layer were grasped with tissue forceps and brought together. Three to four titanium clips were applied in a nearly horizontal direction to close the longitudinal line of the muscle layer over the implanted ureter. In this way, the distal ureter was embedded in a seromuscular vesical tunnel, thus creating the antireflux tunnel. In order to avoid ureter damage or occlusion by clips, the distal ureter was pressed down while the detrusor muscle layer was being closed with straight titanium clips(THICON ENDO-SURGERY, USA, LT300).Hand-sutured without routine ureteric stenting ureteroneocystostomyThe technique has been previously described in detail by Lich and Gregoir. In brief, an incision of the bladder mucosa was made in the distal edge of the myotomy. Using interrupted 5-0 Vicryl suture, a direct anastomosis was carried out between the spatulated end of the ureter and the bladder mucosa. After that, the two longitudinal lines of muscle layer were closed togerther over the ureter with interrupted DJ 4-0 sutures to create the antireflux tunnel.Hand-sutured with routine ureteric stenting ureteroneocystostomySame operational procedure has been done according to Lich and Gregoir technique above described, by way of addition, we have adopted the ureteral stenting technique correspondingly. The stent was a silastic urologic J–J stent which ranged in size from 5 to 7 Fr and in length from 12 to 14 cm. In order to removal this device postoperatively, we have the DJS to join the urethral catheter with 7 # silk suture during the operation Period. The stent was removed when the urinary bladder catheter was routinely removed approximately 2 weeks after surgery. After that, the two longitudinal lines of muscle layer were closed togerther over the ureter with interrupted DJ 4-0 sutures to create the antireflux tunnel. One of our experienced surgeons (Gang Ye) performed all suture-free procedure and another skillful surgeon (Feng Zhou) performed each hand-sutured anastomosis. Intraoperative data collection included the diameters of the ureter, ureterovesical anastomosis time, muscle layer closure time and total ureteroneocystostomy time. The absence of leakage of urine was confirmed by bladder filling. The laparotomy incision was closed in layers. The animals were allowed to recover and were then placed in standard animal care facilities. The urethral catheter (6-8 F) and DJS was left in for at least 2 weeks.Postoperative Assessment and Follow-upAll animals were followed for 3 months and were monthly evaluated by color ultrasonography. When the follow-up was scheduled to end, all dogs were evaluated by ascending cystography and retrograde Cystography and the Whitaker test under general anesthesia. TheWhitaker test was utilized to study the intrapelvic pressure of the corresponding and the normal contralateral renal units. The urodynamic evaluation was carried out b insertion of a cannula (F5 ) into the renal pelvis. The cannula had a Y connection for infusion of warm saline (2.2 ml/min) and simultaneous recording of intrapelvic pressure profile. The recording system was DUET MULTI-P, (Medtronic,USA).The animals were then sacrificed (still under anesthesia) using saturated potassium chloride. The urinary tract was excised and harvested. The bladder and ureter were opened without any damage of the new ureterovesical junction. The anastomosis sites were assessed for surface irregularities, bare clips or suture material or calculus formation under surgical microscope. The new ureterovesical junctions were catheterized with a ureteral catheter, and prepared for investigation with microscope. The specimens for histologic examination were fixed in formalin (the clips were removed by microdissection). The paraffin blocks were prepared, and multiple sections of the specimens stained with hematoxylin-eosin (H&E) for histologic examination. Collagen fibers observed by Masson staining in ureteral and renal tissue sections. Collagen I,Шin the upper and the lower ureteral and renal tissues was assessed by immunohistochemical method. The expression of Collagen I,Шin the upper and the lower ureter and the kidney was detected with Western Blot. The changes of the new ureter orifice open construction with the mechanical anastomosis were observed under the scanning electron microscope. Statistical analysisThe data are presented as the mean±S.E.M. The paired t-test was used for statistical analysis with significance at the 0.05 level.RESULTSThe ureterovesival anastomosis with the ring pin stapler was successfully completed in our studies. The antireflux tunnel construction with titanium clips also had a 100% technical success rate. The diameter of ureteral end included in the anastomosis was 2.94±0.13mm (range from 2.5-3.5mm), which showed no significant difference when compared with that in the other group. The 3.5 mm ring was applied in 2 cases, and 3mm ring in 4 and 2.5mm in 3 animals. The time required for extravesical ureteroneocystostomy in the three groups are summarized. Compared with manual suturing anastomosis, the suture-free technique with ring-pin stapler took a significantly shortest time. The time required for mechanical ureter reimplantation is only about 1/2 of that required for suturing anastomosis. All of the animals survived the surgical procedures and had an uneventful recovery, but one dog of groupШhad died of postpoertive infection. At 3-month follow-up, all ureters in Group I was patent with no sign of ureter dilation or hydronephrosis. However, 1 dog of Group II showed evidence of ureteral dilation with hydronephroses on color ultrasonography, which were subsequently confirmed by IVP studies. In our study, ascending cystography demonstrated that no vesicoureteral reflux was detected after ring-pin stapler, but one dog of suture groupШhad vesicoureteral reflux. The results of urodynamic evaluation showed that the baseline pressure of the pelviswas 1 to 2cm water. The intrapelvic pressure of the normal contralateral kidney ranged from 4 to 6 cm water (mean, 2.8 ,5.9 and 7.6 cm water for Group I , Group II and GroupШ, respectively). The intrapelvic pressure of the corresponding kidneys of the Group I and GroupШwas approximately normal. One case with hydronephrosis of group II had higher intrapelvic pressures of 21 cm water.Necropsy examination revealed no signs of skin and urinary tract infection, urinary cyst, and fistulas occurred in any canines of Group I and Group II. One dog of GroupШwas revealed that it died of urinary tract infection by necropsy examination postoperative. All the dogs of the group I showed normal renoureteral units, while 1 dog of group II and1 dog of groupШshowed dilation of corresponding renoureteral units, which are in accordance with that finding of IVP and ascending cystography. The inner surface at the new ureterovesical junction was smooth without any bare pins in 9 specimens of the stapler group. The anastomosic site at the time of autopsy and histological examination showed the epithelial integrity overlying the staples of the new ureterovesical junction. In two specimens of Group II, the mucosal irregularities were seen at the anastomsis site, whereas in the remaining 7 specimens 9 specimens of GroupШ, the inner surface was smooth. There was no sign of calculus formation detected in any of the reimplantation sites of Group I and Group II. One dog of groupШwas detected calculus formation around of the dislodged and kinking distal DJS. Collagen fibers observed by Masson staining in ureteral and renal tissue sections. The expression of Collagen I,Шwas measured through immunohistochemical method, Western Blot in the upper and the lower ureter and the kidney of group I, II andШ. Compared with group II～Ш, the expression of Collagen I,Шof the upper and the lower ureteral and renal tissues was similar in group I (P>0.05). The scanning electron microscope showed the integral epithelial overlying the ureterovesical anastomotic site using the mechanical anastomosis without sign of calculus formation.CONCLUSIONIn conclusion, the suture-free technique with ring pin stapler is suitable for extravesical ureteroneocystostomy. This technique can maintain the new ureter orifice open, allowing good urine excrection and making use of stents unnecessary. Our technique is a quick and safe way to perform ureteroneocystostomy, and could result in a probably lower complication rate. Although this experiment demonstrates the safety, speed, and technical ease of extravesical ureteroneocystostomy using the titanium ring pin stapler system in canine's ureteral reimplantation, there is no doubt that conventional suturing will continue to be the gold standard until futher data are available. Clearly, further investigations with a longer term of follow-up are needed to confirm the preliminary results.
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