Fate of accessory renal arteries in grafts with multiple renal arteries during live-donor renal allo-transplantation.

INTRODUCTION: To determine risk factors for and the effects of impaired perfusion (IP)-"reduced or non-perfusion"-of graft areas supplied by an accessory artery on allograft function. OBJECTIVES: One hundred five consecutive grafts with multiple renal arteries were prospectively evaluated using Doppler ultrasound (US) to detect the perfusion of allograft segments supplied by the accessory artery. We studied factors predicting and the effects of IP on graft function. RESULTS: Doppler US diagnosed IP of allograft accessory arteries in 11 (10.5%) allografts. Mean values ± standard deviations and median (range) of renographic clearance of grafts with IP were 50.5 ± 26 and 40 (range, 21-92) mL/min, while those of grafts with patent accessory arteries were 68.6 ± 18.9 and 67.2 (range 21-117; P < .01). The percentage change in renographic clearance before versus after transplantation increased among grafts with patent arteries and decreased for those with IP (P = .03). On multivariate analysis, factors predicting IP of the accessory artery were delayed graft function (odds ratio [OR] = 9.9; 95% confidence interval [CI] = 1.6-58.6; P = .01) and upper polar arteries (OR = 8.9; 95% CI = 1.8-43.4; P < .01). CONCLUSION: When considering transplants with accessory arteries, greatest attention and efforts should be exerted on upper polar arteries to avoid delayed graft function.

Endogenous BTG2 expression stimulates migration of bladder cancer cells and correlates with poor clinical prognosis for bladder cancer patients.

BACKGROUND: The B-cell translocation gene 2 (BTG2) is considered to act as a tumour-suppressor gene because of its antiproliferative and antimigratory activities. Higher levels of BTG2 expression in tumour cells have been linked to a better clinical outcome for several cancer entities. Here, we investigated the expression and function of BTG2 in bladder cancer. METHODS: The expression of BTG2 in bladder cancer cells was silenced by RNA interference. Cell motility was investigated by wound healing and Boyden chamber assays. The protein expression of BTG2 in bladder cancer was studied by immunohistochemistry. RESULTS: We observed that targeted suppression of BTG2 by RNA interference did not result in growth stimulation but led to a substantial inhibition of bladder cancer cell motility. Tissue microarray analyses of bladder cancer cystectomy specimens revealed that higher BTG2 expression levels within the tumours correlated strongly with a decreased cancer-specific survival for bladder cancer patients. CONCLUSION: These results indicate that endogenous BTG2 expression contributes to the migratory potential of bladder cancer cells. Moreover, high levels of BTG2 in bladder cancers are linked to decreased cancer-specific survival. These findings question the conception that BTG2 generally acts as a tumour suppressor and typically represents a favourable clinical marker for cancer patients.

Role of diffusion-weighted MRI in diagnosis of acute renal allograft dysfunction: a prospective preliminary study.

OBJECTIVE: The aim was to evaluate the effects of diagnostic performance of diffusion-weighted (DW) MRI in the assessment of acute impairment of transplanted kidneys. METHODS: From January 2009 to January 2010, 49 patients with stable renal allograft function (Group 1) and 21 patients with acute graft impairment (Group 2) were included in the study. All patients were evaluated with coronal T(2) weighted (T(2)W) and DW MRI of the kidney. Patients in Group 2 underwent graft biopsy to determine the underlying histopathological aetiology. Apparent diffusion coefficient (ADC) was calculated and the kidneys were studied for any areas of diffusion restriction. Two radiologists, who were blinded to the results of histopathology, independently interpreted the T(2)W and DW images. RESULTS: The histopathological diagnosis of Group 2 (21 patients) was acute cellular rejection (ACR) in 10, acute tubular necrosis (ATN) in 7 and immunosuppressive toxicity in 4 patients. ADC values in Group 1 were significantly higher compared with Group 2 (p<0.001), patients with ACR (p<0.001), patients with ATN (p<0.001) and patients with drug toxicity (p<0.001). Using 2 × 10(-3) mm(2) s(-1) as a cut-off, there was no overlap between the ADC values of patients with normal graft function and those with ATN. Both ACR and ATN had a low ADC value, but on the ADC map the kidney in cases of ATN appears heterogeneous with a characteristic mosaic pattern resembling the Tiger skin. There was no significant T(2)W morphological difference between the two groups. CONCLUSION: These results show how DW MRI is a promising new technique for the diagnosis of acute renal transplant dysfunction.

[Overcontinence in females after orthotopic replacement of the urinary bladder].

Treatment results were analysed for 27 patients (mean age 53 +/- 7 years) after orthotopic urinary diversion (by the method of Studer, Hautmann) following radical cystectomy. Radical cystectomy was performed without nerve preservation in all the patients. Overcontinence was detected in 4 (26.6%) of 15 patients who had undergone urinary diversion by a conventional method. At the average, residual urine was 220 ml. The modified operation for prevention of urine retention was made in 12 subsequent cystectomies. Neobladder topography was studied with MR imaging (MRI) of the pelvic organs and videoroentgenoreservoiroscopy, urodynamic examination was combined with electromyography of the pelvic base muscles. MRI has found that in patients without retention the reservoir was above linea pubbo-coccigeus both at rest and voiding. In patients with overcontinence at rest topographic details by MRI did not differ from those in patients without retention but in stress reservoir changed position. The modification proposed allows one to avoid change in reservoir position and to prevent formation of acute urethra-reservoir angle. Thus, the cause of retention (overcontinence) of the continent orthotopic intestinal neobladder is eliminated.

Co-administration of ketoconazole and tacrolimus therapy: a transplanted rat model.

BACKGROUND/AIM: The aim of this work is to study the safety and the effect of addition of ketoconazole to experimental kidney transplanted rat treated with tacrolimus and predicts the percentage of tacrolimus dose reduction. MATERIAL AND METHODS: The material of this work included 60 male Sprague Dawely rats subjected to renal allotransplantation. They were equally divided into five groups: Group I: served as control group, Group II: received FK506 3.2 mg/kg/bw, Group III: received FK506 2 mg/kg/bw, Group IV: received FK506 1 mg/kg/bw, Group V: received FK506 1 mg/kg/bw plus Ketoconazole 20 mg/kg/day. FK506 trough level and laboratory investigations were determined at 0, 3, 7, 10, 14, and 27 days post-transplantation. RESULTS: In all groups loss of body weight was observed at day 27 after treatment compared to that before transplantation. Serum creatinine significantly increased at day 27 compared to the basal level in groups treated with 1.0 and 3.2 mg FK506 (1.80 +/- 0.50 versus 0.39 +/- 0.06 P = 0.001) and (1.03 +/- 0.26 versus 0.50 +/- 0.07 P = 0.001) respectively, while for 2.0 mg or 1.0 mg plus keto groups, no significant differences in serum creatinine levels over time (0.56 +/- 0.22 versus 0.44 +/- 0.10 P = 0.106) and (0.55 +/- 0.30 versus 0.42 +/- 0.08 P=0.160) were observed. CONCLUSION: Concomitant administration of Ketoconazole and FK506 in transplanted rat model is safe and results in increase of blood trough level concentration of FK506 with 50% reduction of its dose.

Pregnancy outcome after renal allograft transplantation: 15 years experience.

OBJECTIVE: To present our 15 years' experience in the management of 67 pregnancies in renal allograft recipients in Egypt. METHODS: A retrospective study of 67 pregnancies that occurred in 41 renal allograft recipients over the last 15 years. The study was performed in Department of Obstetrics & Gynecology, and Nephrology & Urology Center at Mansoura University, Egypt. RESULTS: Gestational diabetes occurred in 5.7%, infection in 13.4% and proteinuric hypertension in 19.2% of pregnancies. Graft dysfunction and obstructive uropathy occurred in 30.7% and 9.6% of pregnancies, respectively, but no episodes of graft rejection were reported. Pre-term labour was found in 40.9% and fetal growth retardation occurred in 19.2% of pregnancies. Perinatal mortality was in the order of 9.6%. Pregnancy outcome was better in non-cyclosporine group, in non-proteinuric hypertensive groups and in repeated pregnancies compared to the counter groups. CONCLUSION: Although pregnancy in renal transplant recipients is high-risk, successful outcome is expected for singleton pregnancy and is even better with repeated pregnancies in those cases with stable and good graft function. This satisfactory outcome is generally achieved if the graft is stable and the post-transplant interval is more than 2 years.

Surgical atlas: Orthotopic bladder substitution in women after cystectomy for bladder cancer.

Orthotopic bladder substitution after cystectomy in women is feasible. The rate of continence is comparable to that in men who have been similarly treated. Over continence (which is common) is caused by posterior and caudal displacement of the neobladder. Prevention of this descent can reduce the incidence of this complication. Further follow-up is needed to evaluate the oncological outcome.

Extended radical lymphadenectomy in patients with urothelial bladder cancer: results of a prospective multicenter study.

PURPOSE: Previous studies demonstrate a positive correlation between postoperative survival and the extent of pelvic lymphadenectomies in patients with bladder cancer. However, the distribution of nodal metastases has not been examined in sufficient detail. Therefore, we conducted a comprehensive prospective analysis of lymph node metastases to obtain precise knowledge about the pattern of lymphatic tumor spread. MATERIALS AND METHODS: Between 1999 and 2002 we performed 290 radical cystectomies and extended lymphadenectomies. Cranial border of the lymphadenectomy was the level of the inferior mesenteric artery, lateral border was the genitofemoral nerve and caudal border was the pelvic floor. We made every effort to excise and examine microscopically all lymph nodes from 12 well-defined anatomical locations. RESULTS: Mean total number and standard deviation of lymph nodes removed was 43.1 +/- 16.1. Nodal metastases were present in 27.9% of patients. The percentage of metastases at different sites ranged from 14.1% (right obturator nodes) to 2.9% (right paracaval nodes above the aortic bifurcation). By studying cases of unilateral primary tumors or with only 1 metastasis we observed a preferred pattern of metastatic spread. However, there were many exceptions to the rule and we did not identify a well-defined sentinel lymph node. CONCLUSIONS: We strongly recommend extended radical lymphadenectomy to all patients undergoing radical cystectomy for bladder cancer to remove all metastatic tumor deposits completely. The operation can be conducted in routine clinical practice and our data may serve as a guideline for future standardization and quality control of the procedure.

Renal transplantation in children with abnormal lower urinary tract.

OBJECTIVE: This retrospective study reports the outcomes as well as pre- and posttransplant urologic treatments of renal transplantation for children with an abnormal lower urinary tract (LUT). METHODS: Between March 1981 and December 2001, 195 children (< or =18 years of age) received live-donor kidney transplants. The 15 recipients (14 boys and 1 girl, mean age 13.5 +/- 3 years) who had lower urinary tract disorders included posterior urethral valves (PUV) with valve bladder (n=12) and neuropathic bladders secondary to meningomyelocele (n=3). These children were evaluated by voiding cystourethrogram, cystourethroscopy, and cystometry. The children with PUV were maintained on clean intermittent catheterization (CIC) and a detrusor relaxant at least 3 months before transplantation. Augmentation ileocystoplasty or continent cutaneous diversion were used in three patients. The graft and patient survivals as well as complications in this cohort was compared with a group of children with normal LUT, who underwent renal transplantation during the same period. RESULTS: One child died in the early posttransplant period due to rupture of the external iliac artery. Follow-up ranged from 6 months to 16 years (mean=4.5 years). During the same period the graft and patient survival rates were comparable between the group of children with versus without abnormal LUT. Furthermore, mean serum creatinine and creatinine clearance values were also comparable. The group with an abnormal LUT showed a higher incidence of urinary fistula (3/14) and recurrent UTI and/or bacteremia (4/14). CONCLUSIONS: Renal transplantation is feasible with good results for children with abnormal LUT. Pre- and posttransplant urologic management is critical for a successful outcome. However these children display a high incidence of urologic and infectious complications.

Short-term results of rotoresection for benign prostatic hyperplasia: a prospective study of safety and efficacy.

OBJECTIVE: To assess the safety and efficacy of rotoresection as a method for treating benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: Thirty patients were prospectively enrolled between September 2000 and May 2001 (mean age 61 years, sd 6, range 52-78). All patients had a symptom score (AUA) of > 12, a maximum urinary flow rate (Qmax) of < 12 mL/s, a prostate of 20-80 mL and a prostate-specific antigen (PSA) level of 0-4 ng/mL. Patients with prostate or bladder cancer, a PSA level of > 10 ng/mL, previous prostate surgery, previous pelvic surgery, urethral stricture, active urinary tract infection (UTI), acute urine retention, neuropathic bladder and a serum creatinine of > 1.8 mg/mL were excluded. The adenoma was resected using the Rotoresect system (Karl Storz, Tuttlingen, Germany); the mean (sd) operative duration was 45.2 (9.9) min. The catheter was removed after 1.97 (0.3) days and patients assessed at 1, 3 and 6 months after surgery by an AUA score, Qmax, blood haemoglobin level, urine analysis and transrectal ultrasonography; all patients but two completed the follow-up. RESULTS: At 6 months the mean (sd) AUA score decreased from 20.5 (3.8) to 1.6 (1.3), the Qmax increased from 8.7 (2) to 25.3 (12.6) mL/s, and the total prostate volume decreased from 36.5 (13) to 20.5 (7.8) mL. The mean initial haemoglobin level was 138 (10) g/L and at 1 month was 135 (12) g/L. No patient required a blood transfusion or had signs of transurethral resection syndrome. Early complications included UTI and mild stress incontinence in 10 and 11 patients, respectively. At 6 months these patients had sterile urine and were continent. Two patients had a urethral stricture and posterior urethral stone at 6 months and were treated successfully. CONCLUSION: In the short-term, rotoresection is a safe and effective method for treating BPH; there was no significant blood loss or resection syndrome. The hospital stay was short, with excellent functional results.

Superficial bladder tumours: analysis of prognostic factors and construction of a predictive index.

OBJECTIVES: To assess the prognostic factors that could be used to predict tumour recurrence and progression, and to construct and validate a predictive index. PATIENTS AND METHODS: Between June 1991 and December 2000, 533 patients (418 men and 115 women; mean age 55.4 years) underwent complete transurethral resection of histologically confirmed pTa and pT1 transitional cell carcinoma of the bladder, after which 377 (test series) were randomized into two subsequent studies, of six groups, to receive adjuvant intravesical sequential bacillus Calmette-Guérin (BCG) and epirubicin, BCG alone, epirubicin (50 or 80 mg), adriamycin 50 mg or no adjuvant therapy. Factors potentially affecting tumour recurrence or progression were assessed using univariate and multivariate analysis, i.e. tumour stage, histological grade, DNA ploidy, history of recurrence, multiplicity, size, tumour configuration, associated carcinoma in situ, recurrence at the first 3-month check cystoscopy and the use of adjuvant therapy. The regression coefficients determined by Cox regression analysis were used to construct a predictive index (PI). The algebraic sum of the regression coefficients of the factors with independent and significant association with disease-free survival for each case represented a proportional hazard score (PHS). The PI was validated in another series of 156 patients (validation series) in whom the same regression coefficients for the same significant factors as the test series were used to categorize it into three risk groups. Kaplan-Meier survival curves were plotted to compare the different risk categories in both test and validation series. RESULTS: The mean (sd, range) follow-up in the test and validation series were 58 (19, 5-96) and 28.3 (14.9, 2-94) months, respectively. In the test series, tumour stage, DNA ploidy, multiplicity, history of recurrence, tumour configuration, cystoscopy result and the type of adjuvant therapy had independent significance for recurrence on multivariate analysis. For progression, the cystoscopy result, DNA ploidy and grade were the only independent and significant predictors. The ranges of PHS for the factors affecting recurrence-free and progression-free survival were 0.0-7.14 and 0.0-5.84, respectively, which were divided equally into three risk categories with significant differences on Kaplan-Meier curves and a log-rank test (P < 0.001). The three categories in the validation series were significantly different from each other and each was comparable with that in the test series. CONCLUSIONS: Tumour stage, DNA ploidy, multiplicity, history of recurrence, tumour configuration and type of adjuvant therapy affected independently the rate of recurrence after resecting superficial bladder tumour. Recurrence at the 3-month cystoscopy, histological grade and DNA ploidy were the only predictors of progression to muscle-invasion. The PI dividing the patients into three risk groups with different treatment and follow-up strategies for recurrence and progression was reproducible in a validation series.

The urethral Kock pouch: long-term functional and oncological results in men.

OBJECTIVE: To evaluate our experience with men who underwent radical cystectomy and urethral Kock pouch construction between January 1986 and January 1996. PATIENTS AND METHODS: Complications were classified as early (within the first 3 months after surgery) or late. Continence was assessed by interviewing the patient; they were considered continent if they were completely dry with no need of protection by pads, condom catheter or medication. The patients were followed oncologically and Kaplan-Meier survival curves constructed. Urodynamic studies were used to define the possible causes of enuresis. RESULTS: Three patients died after surgery from pulmonary embolism. There were 67 early complications in 63 patients. The mean (SD) follow-up was 87.8 (49.1) months. There were 111 treatment failures from cancer; of these, four men only had an isolated local recurrence in the urethra. Late complications included 72 pouch stones in 55 patients, and 36 deteriorated renal units caused by reflux (17), uretero-ileal stricture (11), nipple valve eversion (four) or stenosis (four). Interestingly, 65 renal units that were dilated before surgery improved significantly afterward. Ileo-urethral strictures occurred in seven men and anterior urethral strictures in six. Nine patients were totally incontinent and two had chronic urinary retention. Daytime continence was complete in 94% of men, with nocturnal enuresis in 55; the latter had significantly more residual urine, and a higher amplitude and duration of phasic contractions. CONCLUSIONS: Orthotopic bladder substitution after cystectomy for cancer is feasible, with good functional and oncological outcomes in properly selected patients. Nevertheless, the use of a hemi-Kock pouch is associated with many valve-related complications.

Nerve-sparing robot-assisted radical cystoprostatectomy and urinary diversion.

OBJECTIVE: To develop a technique of nerve-sparing robot-assisted radical cystoprostatectomy (RRCP) for patients with bladder cancer. PATIENTS AND METHODS: Robotic assistance should enhance the ability to preserve the neurovascular bundles during laparoscopic radical cystectomy. Thus we undertook RRCP and urinary diversion using a three-step technique. First, using a six-port approach and the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA, USA), one surgeon carried out a complete pelvic lymphadenectomy and cystoprostatectomy using a technique developed specifically for robotic surgery. The neurovascular bundles were easily identified and dissected away, the specimen entrapped in a bag and removed through a 5-6 cm suprapubic incision. Second, a different surgical team exteriorized the bowel through this incision and created a neobladder extracorporeally. Third, the neobladder was internalized, the incision closed and the primary surgeon completed the urethro-neovesical anastomosis with robotic assistance. RESULTS: RRCP was carried out in 14 men and three women by the primary surgeon (M.M.). The form of urinary reconstruction was ileal conduit in three, a W-pouch with a serosal-lined tunnel in 10, a double-chimney or a T-pouch with a serosal-lined tunnel in two each. The mean operative duration for robotic radical cystectomy, ileal conduit and orthotopic neobladder were 140, 120 and 168 min, respectively. The mean blood loss was < 150 mL. The number of lymph nodes removed was 4-27, with one patient having N1 disease. The margins of resection were free of tumour in all patients. CONCLUSIONS: We developed a technique for nerve-sparing RRCP using the da Vinci system which allows precise and rapid removal of the bladder with minimal blood loss. The bowel segment can be exteriorized and the most complex form of orthotopic bladder can be created through the incision used to deliver the cystectomy specimen. Performing this part of the operation extracorporeally reduced the operative duration.

Bone loss in pediatric renal transplant recipients.

The factors that affect bone mineral density (BMD) and the long term progress of BMD after transplantation in children is still unknown. Therefore we performed a cross-sectional study to determine BMD in 83 recipients who received living renal allotransplants in Mansoura Urology & Nephrology Center between 1981 and 2001 (mean age at transplantation 13.2 +/- 3.1 years) by dual energy x-ray absorptiometry at various time intervals up to 16 years after transplantation (mean duration after transplantation was 48 +/- 34 months, range 6-192 months). The Z-score for lumbar spine was -2.28 +/- 2.06 and -1.44 +/- 1.44 for the total body. Osteopenia/osteoporosis were present in about two thirds of our kidney transplant recipients. The significant predictors for osteopenia/osteoporosis by univariate analysis were cyclosporine based immunosuppression, the cumulative steroid dose/m2 surface area, graft dysfunction and the urinary deoxypyridinoline. Using logistic regression analysis the cumulative steroid dose/m2 surface area and the urinary deoxypyridinoline were the major significant predictors for bone loss.

Role of urinary transforming growth factor-beta1 concentration in the diagnosis of upper urinary tract obstruction in children.

PURPOSE: We evaluate the role of transforming growth factor-beta1 (TGF-beta1) in the diagnosis and followup of children with pelviureteral junction obstruction. MATERIALS AND METHODS: TGF-beta1 concentration was measured in renal pelvic and bladder urine samples obtained from 15 children who underwent surgery for symptomatic unilateral pelviureteral junction obstruction. Bladder urine TGF-beta1 was also measured in 11 age matched patients with dilated nonobstructed kidneys as documented by nonobstructed washout curve and half-time drainage less than 10 minutes on diuretic renography. In the obstructed group bladder urine TGF-beta1 was measured 3 months after surgery. RESULTS: In the obstructed group mean TGF-beta1 plus or minus SD in the renal pelvic urine was 285 +/- 191 pg./mg. creatinine, or 4-fold that of bladder urine (p >0.001). Mean bladder urine TGF-beta1 was 3-fold higher in patients with upper tract obstruction than in controls (68 +/- 59 versus 22 +/- 18 pg./mg. creatinine, p <0.003). Mean bladder TGF-beta1 3 months after surgery showed a trend towards a decrease, albeit still insignificant (68 +/- 59 versus 39 +/- 31 pg./mg. creatinine for preoperatively versus postoperatively, p <0.08). Using a bladder urine concentration of 29 pg./mg. creatinine as a cutoff between obstruction and no obstruction, TGF-beta1 was 80% sensitive, 82% specific and 81% accurate for the diagnosis of obstruction. CONCLUSIONS: Bladder urine TGF-beta1 is a useful noninvasive tool for diagnosis of upper urinary tract obstruction. At 3 months following corrective surgery there is a trend towards decrease in bladder TGF-beta1 concentration in comparison to the preoperative value.

Ureteroneocystostomy in children with posterior urethral valves: indications and outcome.

PURPOSE: Ureteroneocystostomy in children with posterior urethral valves represents a surgical challenge. We reviewed our experience with this procedure to assess its indications and outcome. MATERIALS AND METHODS: Between 1996 and January 2000, 106 children with posterior urethral valves were treated of whom 20 (19%) underwent ureteroneocystostomy at a mean age plus or minus SD of 5 +/- 2.6 years. Indications for surgery were recurrent urinary infections despite adequate valve ablation in 14 patients of whom 7 had persistent reflux in 12 renal units and 7 had obstruction in 11 ureterovesical junctions. The remaining 6 patients were initially treated with high loop diversion and obstruction was confirmed in 9 ureterovesical junctions by the Whitaker test. Bladder function was assessed by videourodynamics before surgery. Transureteroureterostomy was performed in 7 ureters, and 25 ureters were tailored and reimplanted using the combined intravesical and extravesical approach, including a psoas hitch in 18 (72%). RESULTS: Mean followup plus or minus SD was 2.3 +/- 1 years. Obstruction and reflux occurred in 1 (4%) and 9 (36%) ureteroneocystostomies, respectively. Obstruction was successfully managed by repeat surgery. Patients with reflux were maintained on chemoprophylaxis. No patient required repeat surgery and reflux did not resolve spontaneously in any. Reflux occurred in all ureteroneocystostomies without a psoas hitch (100%) and in 2 with a hitch (10%) (p <0.004). Dilatation of the upper tracts persisted in all patients. In 2 patients end stage renal disease developed. The remaining 18 patients had serial sterile urine cultures and with a mean serum creatinine plus or minus SD of 0.8 +/- 0.3 mg.%. CONCLUSIONS: Ureteroneocystostomy is indicated for patients with persistent obstruction after high diversion or those with persistent reflux or obstruction and recurrent infections despite adequate valve ablation and a stable bladder. However, the procedure is associated with a high rate of postoperative reflux. Psoas hitch has a significant role in prevention of reflux.

Treatment of urethral defects: skin, buccal or bladder mucosa, tube or patch? An experimental study in dogs.

PURPOSE: We studied 3 graft materials and 2 urethroplasty techniques in 24 adult male mongrel dogs. MATERIALS AND METHODS: The animals were divided into 2 equal groups. In group 1 a 4 cm. segment of perineal urethra was excised and tubed urethroplasty was performed using free full-thickness skin, buccal and bladder mucosa grafts in 4 dogs each. In group 2 a 4 cm. urethral strip was excised and onlay urethroplasty was performed using the same graft materials in 4 dogs each. Retrograde urethrography was done and the animals were sacrificed at week 12. Autopsy specimens were calibrated with a 10Fr catheter. Hematoxylin and eosin stained sections were examined. Masson's trichrome stain was used to determine the extent of fibrosis. RESULTS: Urethral stricture was diagnosed by radiology and confirmed by calibration in 8 of the 12 dogs (66%) in group 1 but in only 1 of the 12 (8%) in group 2 (p <0.004). Buccal mucosa grafts were associated with the lowest stricture rate of 12%, followed by 37% for bladder mucosa and 62% for skin (p <0.2). There was no difference in neovascularization among the 3 grafts. Graft shrinkage was less than 10% for buccal mucosa compared with 20% to 40% for skin and bladder mucosa. The shrinkage rate was similar for the onlay and tube techniques. The intensity of chronic inflammation and fibrosis was highest in the skin grafts. Circumferential fibrosis was noted in association with tubed urethroplasty but not with the onlay technique. CONCLUSIONS: The theoretical advantages of buccal mucosal grafts were pathologically demonstrated. When possible, grafts should be used as an onlay rather than as a complete tube.