Regeneration of functional bladder substitutes using large segment acellular matrix allografts in a porcine model.

PURPOSE: We previously reported on the short-term (4 weeks) morphometric analysis of a large bladder acellular matrix allograft used as a bladder bioprosthesis (average size 24 cm.2). We demonstrated cellular repopulation through the entire thickness of the graft. We now present the long-term (12 weeks) morphometric results of graft regenerated porcine bladders using segments measuring an average of 40 cm.2. MATERIALS AND METHODS: Bladders harvested from pigs were subjected to detergent and enzymatic extractions to render them acellular. Partial cystectomy was performed in 21 pigs and the defect was repaired with a bladder acellular matrix allograft (average size 40.52 cm.2). Of the animals 8 were sacrificed at 1, 2 and 4 weeks and 13 were sacrificed at 8 and 12 weeks. To evaluate cellular repopulation and matrix reorganization the native bladder and graft were analyzed using standard histological and immunofluorescent techniques. To evaluate for calcium deposits in the grafts a radiological evaluation of the graft was performed after explantation. RESULTS: All animals survived the surgical procedure and there were no significant urinary leaks. No stones were noted in any of the bladders. At 1 week there was a diffuse infiltration with acute inflammatory cells. At 2 weeks the luminal surface of the graft was lined with a single layer of urothelium, and there was stromal infiltration with unorganized smooth muscle cells and angiogenesis. At 4 weeks the urothelium was multilayered with organizing groups of smooth muscle cells and angiogenesis. At 8 and 12 weeks there was repopulation throughout the bladder acellular matrix allograft implant with all native cellular components participating. CONCLUSIONS: We present evidence that large patch bladder acellular matrix allograft implantation is technically feasible and may prove to be a viable surgical alternative to bladder augmentation with intestinal segments. Its advantages may include the potential for complete and functional regeneration of a bladder substitute.

Lessons learned from laser tissue soldering and fibrin glue pyeloplasty in an in vivo porcine model.

PURPOSE: We compared sutured pyeloplasty to 2 newer techniques of tissue anastomosis, including laser soldered pyeloplasty using a diode laser with 50% albumin solder mixed with indocyanine green and fibrin glue. MATERIALS AND METHODS: We performed 53 pyeloplasties in 50 pigs using suture, laser or fibrin glue. In the immediate group anastomotic leak pressure was measured immediately postoperatively, and then animals were euthanized. At 1, 3 and 4 weeks postoperatively a pressure flow study at 10 cc per minute in cm. H2O was performed, and tissue was sent for histological and collagen content analysis. RESULTS: In the immediate studies laser soldering achieved a significantly higher mean anastomotic leak pressure (50.5 +/- 15.1 cm. H2O) than sutured (17.3 +/- 5.4) or fibrin glued (3.5 +/- 1.5) repairs. In the 1, 2 and 4-week studies animals in the sutured pyeloplasty group had no complications, and all pressure flow studies except 1 were normal. However, in the laser soldered groups we observed 8 urinomas in 19 animals, and most occurred during the first part of our study. This complication was prevented by stopping urine flow at the anastomotic site at laser irradiation and by improving application of the solder. Of the 11 animals in which pressure flow studies were performed only 2 were obstructed. Of the 7 chronic fibrin glue group 4 animals had urinomas and 2 had unobstructed pressure flow studies. Histological studies and immunohistochemical staining for collagen showed no differences in collagen distribution among the 3 procedures. CONCLUSIONS: Laser soldering and fibrin glue pyeloplasties are not superior in the long-term compared to sutured pyeloplasty. Fibrin glue in our animal model had the highest failure rate. Further improvements in the technical aspect of laser tissue welding need to be made to benefit from its theoretical advantages in minimally invasive surgery.

Are postoperative studies justified after extravescial ureteral reimplantation?

PURPOSE: We evaluated the usefulness of postoperative imaging studies after extravesical ureteroneocystostomy and identified patient subsets in which these studies are necessary. MATERIALS AND METHODS: Records of 438 patients who had undergone extravesical ureteroneocystostomy from 1991 to 1997 were reviewed retrospectively. Study inclusion criterion was primary reflux with at least 1 year of postoperative followup. Grades I to III reflux were defined as low, and grades IV and V were defined as high. All patients were on prophylactic antibiotics. Evaluation included ultrasound and a voiding cystourethrogram 3 months postoperatively, and if reflux persisted the studies were repeated at 12 months. RESULTS: A total of 438 patients (723 renal units) underwent extravesical ureteral reimplantation. At 3 months the procedure was successful in 93.2% of ureters (91.3% patients), and at 12 months the success rate increased to 97.9% of ureters (95.4% patients). There were 49 renal units in 38 cases that were refluxing at 3 months, 11 of which were contralateral. At 12 months reflux resolved spontaneously in 20 of 38 ipsilateral and 8 of 11 contralateral ureters. Of the remaining 18 ipsilateral units reflux was high grade preoperatively in 12 and persisted postoperatively in 4. There was a statistically significant difference in the success rate at 1 year between high (94%) versus low (99%) grade reflux (p = 0.007). Age and preoperative bladder function did not significantly affect the success rates but males had a lower success rate. Hydronephrosis was noted in 7.2% of ureters at 6 weeks and in only 0.005% at 12 months. CONCLUSIONS: Extravesical reimplantation is successful in treating vesicoureteral reflux. Postoperative voiding cystourethrogram should be reserved for high grade reflux. Limiting these studies will help reduce patient discomfort and the cost of treatment.

Acellular bladder matrix allografts in the regeneration of functional bladders: evaluation of large-segment (> 24 cm) substitution in a porcine model.

OBJECTIVES: To evaluate the use of a large-segment (> 24 cm2) bladder substitution with porcine bladder acellular matrix allograft (BAMA) in a large animal model. Materials and methods Bladders were harvested from pigs at the time of necropsy and subjected to detergent and enzymatic extractions to render them acellular. The BAMA produced had the surgical handling and suture-retaining properties of normal bladder tissue. Six pigs had BAMA segments implanted under general anaesthesia, through a low midline abdominal incision and after partial cystectomy. The defect was repaired with a BAMA patch (mean size 43.88 cm2, range 12-72), with no urinary diversion. Two animals each were then killed at 9, 16 and 30 days and the bladders explanted. The native bladder and BAMA patch were analysed morphometrically to evaluate cellular re-population and matrix re-organization. RESULTS: All animals survived surgery; there were no urinary leaks and no stones detected in any of the bladders. At 9 days there was a diffuse infiltration with acute inflammatory cells, but no areas of necrosis. There were isolated areas of smooth muscle cell (SMC) infiltration of the BAMA. At 16 days the luminal surface was lined with a single layer of urothelium, there was stromal infiltration with disorganized SMC and angiogenesis, with mature vessels in the BAMA patch. At 30 days the urothelium was multilayered with organizing groups of SMCs and angiogenesis. The highest cell density was at the periphery of the repopulated BAMA patch, decreasing towards the centre. CONCLUSIONS: The implantation of large patches of BAMA is technically feasible and may prove to be a viable surgical alternative to bladder augmentation with intestinal segments. The advantages of BAMA include the potential for complete and functional regeneration of a bladder substitute. This model provides a tool with which to obtain a better understanding of the cellular and molecular aspects of matrix re-population.

Initial experience with endoscopic holmium laser lithotripsy for pediatric urolithiasis.

PURPOSE: Due to the unavailability of suitable pediatric instruments children have not benefited from advances in endoscopic lithotripsy. This limitation may be overcome by the holmium: YAG laser. We evaluated the indications for, and efficacy and complications of holmium:YAG laser lithotripsy. MATERIALS AND METHODS: We retrospectively reviewed all cases of laser lithotripsy. Access to the calculus was antegrade or retrograde. A solid state holmium:YAG laser was used. RESULTS: Eight patients 4 to 14 years old underwent laser lithotripsy during the study period. Average calculous surface area was 357.13 mm.2 (range 14 to 1,645). Five patients required 1 procedure to render them stone-free, while the remaining 3 required multiple procedures. No complications were associated with laser lithotripsy. CONCLUSIONS: The ability of the holmium:YAG laser to pulverize urinary calculi makes it an alternative choice for lithotripsy. In our series all patients are stone-free with stable renal function. The advantages of the holmium:YAG laser are that it may be precisely applied via small fibers, and it pulverizes calculi with minimal scattering of energy and retropulsion of the calculus, decreasing trauma to tissues at the perioperative site. There is also a lower risk of residual fragments, which is associated with a lower incidence of calculous regrowth. Holmium: YAG laser is safe and effective for treating pediatric urolithiasis.

Urinary retention after bilateral extravesical ureteral reimplantation: does dissection distal to the ureteral orifice have a role?

PURPOSE: We evaluated the outcome and incidence of urinary retention after bilateral detrusorrhaphy using 2 modifications of the original Lich-Gregoir procedure. MATERIALS AND METHODS: We evaluated the charts of 220 patients who underwent correction of bilateral vesicoureteral reflux using the extravesical approach from January 1991 to December 1997. Inverted Y detrusorrhaphy was performed in 154 patients and the advancing suture modification was done in 66. RESULTS: The success rate using the advancing suture technique was 92.4 and 95.4% at 3 and 12 months, respectively. The Y detrusorrhaphy technique was successful in 91.6 and 97.4% of cases at 3 and 12 months, respectively. The difference in the techniques was not statistically significant. Urinary retention developed in 8.4% of the patients who underwent Y detrusorrhaphy compared to 15.2% of those who underwent the advancing suture technique (not statistically significant). However, patients with grades IV and V reflux, children younger than 3 years and boys had significantly (p <0.05) higher postoperative retention rates of 24.6, 35.6 and 20.3%, respectively, when all 220 patients were considered. CONCLUSIONS: Each modification of the original Lich-Gregoir technique is highly effective for treating bilateral vesicoureteral reflux and each is associated with a low rate of temporary urinary retention. Although there seems to be a lower incidence of retention with the Y detrusorrhaphy technique, this was not statistically significant. Because of the higher incidence of urinary retention in young children, boys and/or patients with high grade reflux, we recommend that physicians consider a longer period of catheterization regardless of the technique chosen.

Pediatric genitourinary tumors.

Each year advances are made in the clinical evaluation and treatment of genitourinary tumors in children. Our understanding of cellular, molecular, and genetic processes in tumorigenesis is evolving rapidly. In addition, knowledge concerning long-term outcome and complications associated with current treatments is increasing. In this article, we review recent literature on pediatric rhabdomyosarcoma, Wilms' tumor, and testicular tumors.

Modified Lich-Gregoir ureteral reimplantation: experience of a Canadian center.

PURPOSE: Various techniques of ureteral reimplantation have been described for correction of vesicoureteral reflux. We report our experience regarding the safety and efficacy of a modified Lich-Gregoir extravesical approach. MATERIAL AND METHODS: From January 1991 to January 1996 we evaluated prospectively 256 patients who underwent a modified Lich-Gregoir procedure for correction of vesicoureteral reflux. A total of 385 vesicoureteral units were reimplanted, including 41 duplex systems. The modification to the Lich-Gregoir technique we used consists of ending the paraureteral myotomy with an inverted Y, which permits easier detrusor muscle reapproximation. RESULTS: This procedure was successful initially in 214 of 237 patients, as confirmed by a normal voiding cystourethrogram 4 to 6 months postoperatively. Of the 237 cases persistent vesicoureteral reflux developed in 13 patients, which resolved spontaneously in 9 after 1 year, contralateral reflux developed in 8, which was treated conservatively, and ureteral obstruction developed in 2. Thus, the 1-year overall success rate was 96%. Urinary retention developed in 12 children with bilateral reimplantation (8.3%) with successful recovery in all after conservative management with urethral catheter drainage of 1 week or less. The duration of hospitalization after surgery ranged from 1 to 3 days. CONCLUSIONS: The modified Lich-Gregoir technique of extravesical ureteral reimplantation is successful, simple to perform, reproducible and associated with low morbidity. It also requires minimal hospital stay. These results should encourage the use of this technique when indicated to correct vesicoureteral reflux in children.