intrinsic abnormalities of the upj are the most common cause of obstruction and may result in loss of a functioning renal unit .
the occurrence of extrinsic compression may also be associated with intrinsic abnormalities of the upj .
traditional therapy , in children and adults , is an open surgical reconstruction of the stenotic upj .
however , in adults , endopyelotomy has all but replaced open pyeloplasty for the management of most upj obstruction due to its good success rate , shorter operative time , reduced postoperative morbidity and quicker return to regular activities .
nonetheless , the endourologic surgical management of upj obstruction with reported success rates of 64% to 86% for antegrade and retrograde endopyelotomy is still less than the 90% to 95% success rate cited for open pyeloplasty .
recently , there have been anecdotal reports of laparoscopic pyeloplasty in an attempt to emulate the success rate for open surgery while maintaining the benefits of a minimally invasive procedure .
however , the laparoscopic pyeloplasty has been associated with long operative times : five to seven hours , largely due to the difficulty of intracorporeal suturing .
the introduction of new laparoscopic technology may simplify the procedure to improve its feasibility as an option in the management of a patient with upj obstruction .
as such , this study proposed to evaluate the feasibility of two different laparoscopic techniques for the performance of pyeloplasty repair of secondary upj obstruction : a semi - automatic suturing device ( endostitch , us surgical corporation , norwalk , ct ) and the use of a suture clip knot ( lapra - ty , ethicon endo - surgery , inc . ,
in addition , the study compared the healing results using the two different techniques for performing the laparoscopic pyeloplasty .
sixteen female yucatan mini - pigs were entered into the study . under standardized general endotracheal anesthesia the animals underwent cystoscopy , retrograde pyelography , and urine collection for culture and sensitivity .
unilateral upj obstruction , the side determined by prospective randomization , was created by ligating the upj with a suture ligature .
a 5f ureteral catheter was cystoscopically passed retrograde to the renal pelvis on the experimental side .
a co2 pneumoperitoneum was established at 15 mm hg and a 12 mm port was placed at the level of the umbilicus on the lateral border of the ipsilateral abdominis rectus muscle to the proposed side of upj obstruction .
two additional 5 mm ports were placed on the anterior axillary line just below the costal margin and just above the anterior iliac crest , respectively .
the 30-degree , 10 mm laparoscope was placed through the 12 mm port and grasping forceps and scissors were passed through the two 5 mm ports . the peritoneum was incised at the level of the lower pole of the kidney and extended caudally to expose the proximal ureter .
the proximal ureter was circumferentially dissected from the retroperitoneal tissues minimizing the use of electrocautery in this area .
a six - inch length of an absorbable ( 0-chromic ) ligature was passed twice around the ureteropelvic junction , at the level of the lower pole of the kidney , and tied in position using an intracorporeal knot - tying technique .
the retrograde catheter was maintained for 30 minutes and then removed and the animal was recovered .
six weeks following creation of the ureteropelvic junction obstruction , all animals underwent standardized general anesthesia , and the following evaluations were performed : serum creatinine , cystoscopy and bilateral retrograde pyelography with collection of urine for culture and sensitivity , renal scan and insertion of a 0.035 inch bentson guidewire into the upper collecting system .
twelve animals then underwent a laparoscopic pyeloplasty utilizing an intracorporeal suturing technique and lapra - ty ( ethicon endosugery , inc . ,
the lapra - ty ( ethicon endo - surgery , inc . , cincinnati , oh ) suture clip is made of absorbable polydioxanone material . no further surgical manipulation , following creation of the stricture , was per - formed on the four animals which served as a control model .
after establishment of a 15 mm hg pneumoperitoneum , using veress needle insufflation , four ports were placed : a 12 mm port along the midclavicular line at the level of the umbilicus , a 12 mm port along the anterior axillary line just below the costal margin , a 12 mm port along the anterior axillary line approximately 3 cm below the umbilicus , and a 5 mm port on the posterior axillary line midway between the costal line and the iliac crest .
a 10 mm , 30-degree laparoscope was positioned through the 12 mm midclavicular line port .
using electrosurgical scissors and grasping forceps the peritoneum was incised along the line of toldt and this was mobilized medially , thereby similarly mobilizing the bowel medially to expose the ureter and kidney in the retroperitoneum .
the ureter and renal pelvis , 2 cm below and 2 cm above the area of stricture , were freed sufficiently to allow excision of the strictured area .
mechanical  cold  cutting scissors were used to transect the ureter and the renal pelvis removing the strictured segment of tissue .
after randomization to either the free hand , intracorporeal suturing or endostitch group , a six - inch length of the polyglactin suture material was utilized with a preformed loop tied at the end of the suture . after passing the needle and suture full thickness , to ensure incorporation of the urothelium , through the posterior renal pelvis and spatulated ureteral side of the anastomosis the suture was passed through the preformed loop securing the initial closure .
a continuous running suturing technique was utilized to approximate the renal pelvis to the ureter with full thickness suturing . in the pig model
following completion of the anastomosis using the intracorporeal technique a lapra - ty suture clip was placed on the suture to secure the anastomotic closure in six animals . in the case of the endostitch device
an intracorporeal knot - tying technique was used with the endostitch device to secure the final anastomotic closure in six animals . in both techniques
satisfactory positioning of a ureteral guidewire in the renal pelvis was accomplished before completion of the closure .
an indwelling 6f double pigtail , ureteral stent was passed over the guidewire fluoroscopically and left in position in the upper collecting system .
no external , retroperitoneal drain was placed ; the retroperitoneum was not re - established .
the ports were removed and the animal was recovered and received tribrissen antibiotic , 48 mg / kg q.d . for seven days .
six weeks following the laparoscopic pyeloplasty , under a standardized general anesthetic , cystoscopy and a gravity cystogram were performed .
if there was no extravasation at the ureteropelvic junction region , the ureteral stent was removed cystoscopically . at three months and six months
post - pyeloplasty all the animals underwent standardized general anesthesia and the following evaluations were obtained : serum creatinine , urine for culture and sensitivity and renal scan . at the six months post - pyeloplasty evaluation all the animals were euthanized and the ureteropelvic junction was calibrated using ureteral catheters sized from 4f to 10f .
hematoxylin and eosin ( h&e ) staining for histopathology was performed on the ureter below the anastomosis , at the anastomosis , and above the anastomosis at the renal pelvis .
the h&e histopathologic evaluation assessed each harvested specimen for the following characteristics : urothelial resurfacing , degree of urothelial inflammation , fibrosis in the lamina propria , inflammation in the lamina propria , fibrosis in the muscle layer , and integrity of the musculature .
each characteristic was given a score of 0 to 3 , with 0=normal histopathology and 3=worst histopathologic effect .
therefore , the total healing score could range from 0=normal histopathology to 15=worst effect in all five histopathologic categories .
comparison of the two study groups and the control group was statistically evaluated using one - way analysis of variance ( anova ) .
comparison within each study group for changes following pyeloplasty was statistically evaluated using nonparametric , unpaired ( mann - whitney ) testing .
the tie - down technique of the ureteropelvic junction , over a 5f catheter , was completed successfully on all 16 animals . the mean ureteral diameter on retrograde pyelography
prior to the tie - down procedure was 3.5 mm . at the time of pyeloplasty
there was complete obstruction of the study ureter on retrograde pyelography in 6 of the 12 study animals ; the remaining study ureters had a mean diameter of 1.7 mm , indicative of significant reduction of the ureteral lumen following the tie - down . on follow - up renal
the average decrease in renal function of the experimental kidney was 37% , indicating almost complete ureteral obstruction and resultant loss of renal function . in the endostitch group
the average decrease was 42% , while the lapra - ty group had an average reduction of 36% and in the control group of animals the reduction in renal function was 33% . at six months follow - up
there had been no improvement in the renal function despite imaging evaluation that confirmed patency of the ureter following pyeloplasty ( figure 1 ) .
comparison of the change in the percentage of function in the treated kidney , by radionucleotide renal scan , at the time of pyeloplasty and at six months following in the two study groups and the control group .
the mean time for laparoscopic pyeloplasty using the lapra - ty surgical clip closure was 39.7 minutes ( range 25 - 57 minutes ) . the mean surgical time for laparoscopic pyeloplasty utilizing
the endostitch closure device was 39.5 minutes ( range 20 - 75 minutes ) ( table 1 ) .
the time for dissection in the two study groups was also similar , ranging between 14 minutes and 60 minutes , depending on the degree of retroperitoneal fibrosis secondary to the ureteral tie - down procedure .
comparison of lapra - ty suture clip and endostitch device for pyeloplasty ( mean  standard deviation ) the change in ureteral diameter , as evaluated by retrograde pyelography , pre - pyeloplasty and post - pyeloplasty in the endostitch pyeloplasty repair , was a reduction of the diameter by 0.48 mm ( range 2.6 - 3.2 mm ) . in the lapra - ty surgical clip pyeloplasty
closure the mean change in ureteral diameter was an increase in the ureteral diameter of 0.85 mm ( range 1.4 - 4.0 mm ) . on statistical analysis
there was no significant difference in the change in the ureteral diameter on comparison of the lapra - ty clip and endostitch pyeloplasty closure .
in all the study animals and the control animals at six months post - pyeloplasty the upj calibrated to 8f easily .
the mean healing score in the endostitch pyeloplasty group was 4.17 ( range 2 - 8) , and in the lapra - ty surgical clip group the mean healing score was 5.92 ( 3 - 9.5 ) ( figure 3 ) .
the mean healing score in the control group of animals was 4.17 ( range 4 - 4.5 ) .
there was no statistically significant difference among the endostitch , lapra - ty clip pyeloplasty ureters and the control ureters on comparison of healing scores .
the primary histopathologic features effecting a higher healing score in the study ureters included fibrosis and inflammation of the lamina propria and muscle layer .
the mean increase in serum creatinine in the endostitch pyeloplasty group was 0.38 mg / dl ( range 0.20 - 0.80 mg / dl ) , in the lapra - ty suture clip pyeloplasty group was 0.12 mg / dl ( range 0.20 - 0.50 mg / dl ) ( figure 2 ) .
the difference in serum creatinine for the endostitch and lapra - ty groups was not statistically significant .
comparison of the change in ureteral diameter , as measured on retrograde pyelography , and the change in serum creatinine in the endostitch and lapra - ty clip laparoscopic pyeloplasty groups after six months of follow - up . comparison of the healing scores at the pyeloplasty anastomosis six months following the laparoscopic pyeloplasty in the endostitch and lapra - ty clip study groups and at the stricture site in the control group .
an interesting observation in both study groups was the frequent formation of a diverticulum at the site of pyeloplasty repair .
this was observed at the six - week post - pyeloplasty , three - months post - pyeloplasty and the six - months post - pyeloplasty retrograde pyelography imaging . in the endostitch group ,
three animals demonstrated diverticular formation ranging between 7.8 mm and 16 mm in diameter ( mean 12.5 mm ) . in the lapra - ty suture clip pyeloplasty group ,
four of the six animals demonstrated ureteral diverticular formation ranging between 5 mm and 13.8 mm in diameter ( mean 10.7 mm ) . in two of the endostitch pyeloplasty animals
the diverticulum was noted to persist at six month follow - up evaluation and in four of the lapra - ty suture clip pyeloplasty animals this phenomenon also persisted until the completion of the study ( figure 4 ) . a retrograde pyelogram demonstrating the diverticulum ( arrow ) formation at the pyeloplasty anastomotic site six weeks following laparoscopic pyeloplasty .
the model developed for creating upj obstruction was not difficult to perform . however , the technique created too severe a ureteral obstruction , with a resultant significant permanent reduction in the renal function .
after six weeks duration the compromise to renal function did not resolve despite creating a patent upj region with the pyeloplasty technique .
this severe effect on renal function may alter the normal excretion of growth factors from the kidney and ultimately affect the results of the pyeloplasty .
we are planning to retest our technique using a larger ureteral catheter for performing the chromic suture tie - down . again
as such it was not possible to assess ureteral obstruction by renal scan t  evaluation due to the com - promised function of the kidney .
however , retrograde pyelography and calibration of the ureteropelvic junction using graduated catheters from a 4f to an 8f allowed evaluation for upj patency at six months following pyeloplasty . the endostitch device and lapra - ty suture clip
the two techniques had a similar surgical time and no particular intraoperative or postoperative complications associated with either .
the techniques used with both instruments was a continuous , circumferential suturing of the anastomosis . the suture was initially secured by passing the needle and suture through a pre - formed loop at the end of the suture and then tightened down , obviating the need for a knot - tying technique at this point . following completion of the anastomosis , the suture was finally secured with either the lapra - ty clip or the knot - tying technique with the endostitch device .
the surgeon performing the pyeloplasty anastomosis had considerable clinical experience with laparoscopic suturing , which may have also contributed to the short operative time for the intracorporeally sutured anastomosis .
overall , there was no significant change in the percent function by renal scan of the treated kidneys comparing the pyeloplasty scan to the six - month follow - up scan in the endostitch , lapra - ty suture clip and control group of animals .
similarly , there was no significant change in the serum creatinine in the endostitch or lapra - ty suture clip groups at six - month follow - up compared to their serum creatinine at the time of pyeloplasty .
the control group showed similar changes in the serum creatinine , suggesting that the creatinine probably represented the function of unobstructed kidney and had minimal effect from the study kidney . the slight increase in creatinine noted in all animals
may also be associated with a general increase in their muscle mass over the six - month study period .
the diverticular formation at the site of the pyeloplasty may be a feature unique to this animal model .
however , the observation of a diverticulum in a large number of the study animals suggests that it may be a component of the reparative process following the pyeloplasty .
there was a trend towards a slightly higher healing score in the lapra - ty suture clip group as compared to the endostitch suture technique , albeit not statistically significant .
interestingly , the mean healing score in the control group was similar to that in the endostitch group . however , there was no statistically significant difference between the healing score in the lapra - ty suture clip group compared to the endostitch or control group of animals . at the time of harvest
there was no evidence of the lapra - ty clip , and the fibrosis at the anastomotic site in both the study groups was grossly similar .
traditionally these patients have been treated with openpyeloplasty with a 90 - 95% success rate .
the development of fiberoptic instrumentation and associated cutting modalities has resulted in the development of the antegrade and retrograde endopyelotomy .
review of the literature has shown success rates close to that of an open pyeloplasty , particularly with the antegrade endopyelotomy , 85 - 88% success .
the more recent addition to the endourologist 's armamentarium , the acucise cutting balloon catheter , has resulted in satisfactory success rates ranging between 67% and 81% while providing the patient with a minimally invasive technique associated with reduced postoperative dis - comfort , a short hospital stay , and a quick return to normal activities .
the controversy as to the adverse impact of a crossing vessel on the success rate of endopyelotomy has raised the question as to whether these patients may be more appropriately managed with pyeloplasty . as a result the application of the laparoscopic approach to pyeloplasty repair of the upj obstruction has been proposed .
the most challenging aspect of this technique is the required intracorporeal suturing and knot tying for completion of the re - anastomosis when dismembered pyeloplasty is performed .
indeed these clinical procedures may require as much as five to seven hours of operative time , with most of it devoted to reconstructing the dismembered upj .
the recent advances in reconstructive technology , including the lapraty suture clip and the endostitch device , have significantly reduced operative times for laparoscopic procedures .
this animal study suggests that there is no significant difference in the time to perform the laparoscopic pyeloplasty with the endostitch device or lapra - ty suture clip technique for a running laparoscopic pyeloplasty .
although this study did not specifically address the option of the combination of the endostitch device to complete the anastomosis and the lapra - ty suture clip to secure the suture , in our clinical experience the combination of these two instruments further simplifies and reduces the laparoscopic procedural time .
kavoussi and colleagues have reported on their clinical experience with the laparoscopic pyeloplasty . they have also noted a significant reduction in their operative time with the use of the endostitch suturing device , albeit they have less extensive experience with this device .
they have reported excellent postoperative success rates with patency by renal scan in 100% of their patients with short term follow - up .
nonetheless , even with this advance in laparoscopic technology , endopyelotomy provides an effective form of minimally invasive management for upj obstruction with shorter operative time , less morbidity , minimal hospital stay , reduced postoperative discomfort and a quicker return to normal activities compared to the laparoscopic pyeloplasty .
however , in those patients who have failed an endopyelotomy or in whom a ureteropelvic junction crossing vessel is felt to be responsible for the obstructive process , the laparoscopic pyeloplasty may be an appropriate surgical option , providing reduced postoperative morbidity and recovery time compared to the open pyeloplasty technique .
the laparoscopic pyeloplasty can be efficiently performed using an intracorporeal suturing technique and the lapraty suture clip or the endostitch device for performing the sutured anastomosis and knotting technique .
both techniques result in good anastomotic patency and minimal fibrosis or inflammatory process at the site of the anastomosis .
 investigates the utility of free - hand laparoscopic suture versus the  sewing machine  technique of an endostitch device during laparoscopic pyeloplasty for ureteropelvic junction obstruction . 
 objective parameters for evaluating the postoperative kidney and suture techniques are used to determine if laparoscopic pyeloplasty may be an option to the open pyeloplasty technique . 
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
CONCLUSION