Use of a digestive mucosal graft in urethroplasty. An experimental study--prospective utilization of the appendix mucosa

Buccal mucosal graft urethroplasty in male cats with traumatic complete urethral rupture

OBJECTIVE

To evaluate the feasibility of buccal mucosal graft urethroplasty for repairing complete urethral rupture in cats.

ANIMALS

15 male domestic shorthair cats with traumatic complete urethral rupture.

PROCEDURES

In each cat, a section of buccal mucosa was harvested, sutured, and formed into a tubule by use of an 8F indwelling catheter as support. This tubular graft was connected to both ruptured ends of the urethra to renew the urinary passage. The catheter was left in place until the absence of leakage was confirmed by positive contrast retrograde urethrography. After spontaneous urination was confirmed, cats were discharged from the hospital. Six months later, urethrography was repeated and owners were asked to score their cats' urinary function and quality of life.

RESULTS

13 cats recovered well following surgery, with no complications in the oral cavity or surgical site and no signs of difficulty or discomfort when urinating. Urethrography 2 weeks and 6 months after surgery revealed no stricture or leakage in the abdominal cavity. The 2 remaining cats developed a urethral stricture and underwent second surgery with a successful outcome. At the 6-month follow-up, 14 cats had only mild urinary signs, and 1 cat had incontinency. Owners indicated they were delighted (n = 14) or pleased (1) with their cats' quality of life.

CLINICAL RELEVANCE

Buccal mucosa was found to be a good source of graft tissue for performance of urethroplasty in male cats, yielding satisfactory outcomes with few postoperative complications. The described technique may be suitable for severe and complicated cases of urethral rupture in male cats.

Use of rectal mucosal grafts in substitution urethroplasty: an early series

Background

To evaluate the feasibility of use of rectal mucosal grafts for augmentation urethroplasty.

Methods

A series of five patients who underwent rectal mucosal graft urethroplasty for urethral stricture disease were identified. Descriptive statistics were used to describe these patients. Primary endpoints were recurrence of stricture and perioperative morbidity.

Results

Five patients underwent rectal mucosal graft augmentation urethroplasty. Four had a history of prior buccal mucosal graft (BMG) urethroplasty and one had a history of head and neck cancer. Rectal mucosa was noted to be thinner and required more tailoring than buccal mucosa. All patients had patent urethras at time of postoperative retrograde urethrogram. A small diverticulum was noted in one patient with no further sequelae. No complications from rectal mucosal graft harvest were noted. All patients with prior buccal grafting subjectively preferred the rectal graft due to fewer side effects. Subjectively, patients with prior buccal grafts preferred the post-operative recovery following rectal mucosal graft urethroplasty.

Conclusions

Rectal mucosal graft augmentation urethroplasty is a safe alternative in patients with contraindications to buccal grafting with limited morbidity.

Preconstruction of the Pars Pendulans Urethrae for Phalloplasty with Digestive Mucosa Using a Prefabricated Anterolateral Thigh Flap in a One-arm Patient

Summary:

We herein report a successful preconstruction of the pars pendulans urethrae with the ileum mucosa for phalloplasty in a one-arm patient using a prefabricated anterolateral thigh flap. After a 2-stage operation and an 18-month follow-up, the patient achieved a good postoperative appearance and an excellent function of neophallus. We believe the use of digestive mucosa for urethral reconstruction enlightens us and deserves further comprehensive clinical studies.

Evaluation of crural release and ischial osteotomy for relief of tension in the repair of large segmental urethral defects in male cats

OBJECTIVE

To examine if the tension at the site of a urethral anastomosis can be relieved by performing either a crural release technique or an ischial osteotomy technique.

STUDY DESIGN

Cadaveric study and 2 case reports.

ANIMALS

Adult male cat cadavers (n = 18).

METHODS

Cats were divided into 2 groups; crural release (n = 9) and ischial osteotomy (n = 9). In each group, 20%, 25%, and 30% of the pelvic urethra was excised in 3 cats. The length of the urethral defect was measured after excision of the urethral segment, and after approximation, before and subsequent to the tension relieving technique performed. Two clinical cases are described.

RESULTS

Both crural release and ischial osteotomy were effective in relieving the tension encountered at the urethral anastomosis after removal of 20% of the urethral length. In the ischial osteotomy group, apposition without tension after removing up to 30% of the intrapelvic urethral length was easily achieved. A similar technique was successfully used in 2 clinical cases.

CONCLUSION

Crural release and ischial osteotomy techniques allow approximation and tension free anastomosis of large segmental defects of the pelvic urethra in cats.

Use of free peritoneal and bladder mucosal grafts as ureteral mucosa substitutes for management of avulsion of the ureteral mucosa in a dog model

BACKGROUND AND PURPOSE

Avulsion of the ureteral mucosa is one of the most serious complications of ureteroscopy and considered challenging for urologic surgeons. In this study, we developed two novel methods to reconstruct the impaired ureter.

MATERIALS AND METHODS

After ureteral mucosal avulsion in a canine model, ureteral reconstruction was performed in one of three ways: free tabularized peritoneal grafts (group A, n = 6); bladder mucosal grafts (group B, n = 6); or simple stenting technique (control group [n = 3]). At postoperative week 10, evaluation with intravenous urography (IVU) was followed by harvesting of reconstructed ureter segments for pathologic analysis.

RESULTS

IVU showed nonvisualization of the collecting system of the affected side and histologic evaluation showed imperforation or stenosis in all animals in the control group. IVU showed good visualization of the reconstructed ureter without stenosis in group A and in most animals in group B. There was a mild dilation but no obvious stenosis in one animal in group B. Microscopically, all the reconstructed ureteral lumens were uniformly lined with transitional epithelium. Extensive neovascularity was evident in the subepithelial layer with a streaming of fibroblasts toward the neomucosa.

CONCLUSION

Replacing the avulsed mucosa in the injured ureter with tubularized peritoneal free grafts or bladder mucosal grafts may be an optimal method to manage avulsion of the ureteral mucosa.

Reconstruction of the urethral defects with autologous fascial tube graft in a rabbit model

AIM

To investigate the feasibility of the autologous fascia graft in urethra defect reconstruction.

METHODS

In 24 adult male rabbits, a standardized defect (17 mm) was created within the midportion of each urethra. Two-cm long fascial tube grafts were interposed between the cut ends of the urethra. Twenty-four rabbits were divided into 12 groups. At 0, 3, 10, 15, 21, 30, 45, 60, 90, 120, 150, and 180 days postoperatively, one group was killed. In the first four groups, rabbits were killed and specimens were obtained for histological examination. After 21 postoperative days, in the subsequent eight groups, retrograde urethrograms were carried out to evaluate urethral patency and caliber, then rabbits were killed and specimens were obtained.

RESULTS

In the histological study, advancement of the urethral transitional epithelium along scaffold provided by the fascial graft was determined. At the 30th day, the new urethra was completely covered with the transitional epithelium. Fistula formation was observed in two of 24 rabbits. In urethrograms, narrowing was determined in three of 16 rabbits.

CONCLUSION

For segmental urethral reconstruction, fascial graft is a good urethral substitute because of its rapid epithelization capacity, low contraction degree and thinness. We therefore propose the use of fascial grafts for reconstruction of male-urethra defects in humans.

Repair of Urethral Defects Using Fascia Lata Autografts in Dogs

OBJECTIVE

To evaluate the feasibility of urethroplasty using a free fascia lata (FL) graft in the dog.

STUDY DESIGN

In vivo experimental study.

ANIMALS

Mixed-breed dogs (n=14).

METHODS

Half of the circumference of the urethra, approximately 1.5 cm long, was excised in 14 male dogs to induce a urethral defect. FL (approximately 2 cm x 2 cm) harvested from the lateral thigh was sutured to the urethra using a 3-0 polyglactin 910 continuous pattern. Dogs were monitored daily for bladder distention and had urethral catheters until normal voiding was observed. On day 60, each dog had a positive contrast urethrogram, and then 8 dogs were euthanatized for gross and histologic examination. Six dogs were monitored for urologic problems for 6 months, and a positive contrast urethrogram was repeated.

RESULTS

All dogs recovered successfully; 4 dogs had difficulty voiding for 2-3 days and urine was aspirated from these dogs every 3 hours until signs of painful urination disappeared. On positive contrast urethrograms, urethral anatomy was considered normal except in 4 dogs that had an irregular contour. Gross urethral examination confirmed an absence of ulceration, stricture, diverticula, or fistula formation, and the FL-lined graft survived in all dogs. No degenerative and reparative responses were observed. On histologic examination of the penile urethra, the lumen was intact, covered with transitional epithelium, and surrounded by corpus spongiosum with cavernous spaces and blood-filled vessels.

CONCLUSIONS

Free FL grafts are incorporated satisfactorily and would appear to be useful for repairing urethral defects.

CLINICAL RELEVANCE

FL grafts should be considered for repair of urethral defects in dogs.

Comparison of Angiogenic Activities after Urethral Reconstruction Using Free Grafts in Rabbits

OBJECTIVE

To determine the most suitable type of graft-free penile skin grafts or mucosal grafts from bladder or buccal regions - for urethral reconstruction in an animal model, as evaluated on the basis of angiogenic activity.

METHODS

Twenty-two male White New Zealand rabbits were randomly divided into four groups. In the control group (group O, n=4) a simple urethrotomy and closure was performed, whereas a ventral urethral defect was created in groups A, B, and C and then bridged using the following onlay patches: free penile skin (group A, n=6), buccal mucosal graft (group B, n=6), and bladder mucosal graft (group C, n=6). On the 21st postoperative day, the animals were sacrificed and the retrieved implants were subjected to macroscopic and microscopic analysis. The angiogenic activity was assessed with immunohistochemistry, using the anti-CD31 MoAb and the phosphatase antialkaline phosphatase procedure. The native vascularity of penile skin as well as buccal and bladder mucosa was assessed in rabbits from group O (n=3). Statistical analysis was performed using the one-way ANOVA.

RESULTS

The angiogenesis in a magnification of x200 in groups O, A, B, and C was 34.1+/-4.1 (mean+/-SD), 61.7+/-6.4, 94.3+/-6.4, and 91.5+/-7.2 vessels per optical field, respectively. There were, statistically significant differences (p<0.001) between groups A and B and between groups A and C, but not (p>0.05) between groups B and C. The native vascularity of penile skin, buccal mucosa and bladder mucosa was 23.3+/-3.0, 24.6+/-3.7 and 17.0+/-2.6 vessels per optical field, respectively.

CONCLUSION

The viability of mucosal grafts from bladder or buccal regions is better than that of a free penile graft because of higher angiogenic activity. Although the mucosal grafts showed the same angiogenic activity, the buccal mucosa graft is preferable because of its easier harvesting.

1-stage urethral reconstruction using colonic mucosa graft for the treatment of a long complex urethral stricture

PURPOSE

We investigated the possibility of urethroplasty with a free graft of colonic mucosa for long, complex urethral strictures. We report our initial experience with colonic mucosa graft urethroplasty for such urethral strictures in 16 patients.

MATERIALS AND METHODS

Between September 2000 and December 2002, 16 patients with a long, complex urethral stricture were treated with colonic mucosal graft urethroplasty. Patients had undergone an average of 2.5 previous unsuccessful repairs. Urethral reconstruction was done with a 10 to 17 cm (median 13) graft of colonic mucosa

RESULTS

Patients were followed 6 to 33 months postoperatively. Meatal stenosis that developed in 1 patient 3 months postoperatively needed reoperation. The patient was voiding well with a urinary peak flow of 28.7 ml per second during 9-month followup after reoperation. Hyperplasia of the verumontanum was observed during urethroscopy and transurethral colliculectomy was performed in 1 patient more than 14 months postoperatively. Uroflowmetry showed a urinary peak flow of 46.5 ml per second postoperatively. The other patients were voiding well with a urinary peak flow of greater than 15 ml per second. Urethrogram revealed a patent urethra with an adequate lumen and no significant graft sacculation.

CONCLUSIONS

This initial experience in 16 patients indicates that colonic mucosa graft urethroplasty is a feasible procedure for long, complex anterior urethral strictures. The technique may be considered for urethral reconstruction when more conventional procedures have failed.

One-stage urethral reconstruction using colonic mucosa graft: An experimental and clinical study

AIM: To investigate the possibility of urethral reconstruction with a free colonic mucosa graft and to present our preliminary experience with urethral substitution using a free graft of colonic mucosa for treatment of 7 patients with complex urethral stricture of a long segment.

METHODS: Ten female dogs underwent a procedure in which the urethral mucosa was totally removed and replaced with a free graft of colonic mucosa. A urodynamic study was performed before the operation and sacrifice. The dogs were sacrificed 8 to 16 wk after the operation for histological examination of urethra. Besides, 7 patients with complex urethral stricture of a long segment were treated by urethroplasty with the use of a colonic mucosal graft. The cases had undergone an average of 3 previous unsuccessful repairs. Urethral reconstruction with a free graft of colonic mucosa ranged from 10 to 17 cm (mean 13.1 cm). Follow-up included urethrography, urethroscopy and uroflowmetry.

RESULTS: Urethral stricture developed in 1 dog. The results of urodynamic studies showed that the difference in the maximum urethral pressure between the pre-operation and pre-sacrifice in the remaining 9 dogs was not of significance (P > 0.05). Histological examination revealed that the colonic free mucosa survived inside the urethral lumen of the 10 experimental dogs. Plicae surface and unilaminar cylindric epithelium of the colonic mucosa was observed in dogs sacrificed 8 wk after the operation. The plicae surface and unilaminar cylindric epithelium of the colonic mucosa was not observed, and metaplastic transitional epithelium covered a large proportion of the urethral mucosa in dogs sacrificed 12 wk after the operation. Clinically, the patients were followed up for 3-18 mo postoperatively (mean 8.5 mo). Meatal stenosis was developed in 1 patient 3 mo postoperatively and needed reoperation. The patient was voiding very well with urinary peak flow 28.7 mL/s during the follow-up of 9 mo after reoperation. The other patients were voiding well with urinary peak flow greater than 15 mL/s. Urethrogram revealed a patent urethra with an adequate lumen with no significant graft sacculation. Neither necrosis of neourethral mucosa nor stenosis at the anastomosis sites has been observed on urethroscopy in 4 patients over 6 mo after operation.

CONCLUSION: Urethral mucosa can be replaced by colonic mucosa without damaging the continence mechanism in female dogs. Colonic mucosa graft urethral substitution is a feasible procedure for the treatment of complex urethral stricture of a long segment. The technique may be considered when more conventional options have failed or are contraindicated.

Free peritoneal grafts for patch urethroplasty in male rabbits

PURPOSE

We evaluated the feasibility of urethroplasty using a free peritoneal graft in a rabbit model.

MATERIALS AND METHODS

In 12 male rabbits a urethral defect was created by excising a 3 x 5 mm. portion of the ventral urethral surface. The defect was immediately repaired with a free peritoneal graft harvested via a left flank incision.

RESULTS

There were 2 intraoperative deaths and 1 death on day 8 postoperatively. These animals were excluded from study. The remaining 1, 4 and 4 rabbits were sacrificed 3, 5 and 9 weeks after surgery, respectively. Macroscopic examination of the urethra revealed no stenosis or diverticula, while a fistula was present in 3 of the 9 animals. Histological study of the fistulous tracts showed chronic granulomatous inflammation. In the remaining 6 rabbits there was graft adherence. The inner surface of the graft was uniformly lined with normal urothelium, while in some cases acute inflammatory cells were present in the subepithelial layer.

CONCLUSIONS

Our experience indicates that the ease of harvesting free peritoneal grafts and their satisfactory adherence to the urethra makes them a valid alternative for repairing urethral defects.

Rabbit urethral regeneration using small intestinal submucosa onlay grafts

OBJECTIVES

To determine if small intestinal submucosa (SIS) can evoke urethral regeneration.

METHODS

Twenty male white New Zealand rabbits were assigned to one of three experimental groups. Group 1 (n = 4) underwent simple urethrotomy and closure. Group 2 (n = 8), a second control group, underwent an onlay urethroplasty with a graft of full-thickness preputial skin from the host rabbit. Group 3 (n = 8) underwent an onlay urethroplasty with an SIS graft.

RESULTS

All eight SIS onlay grafts promoted regeneration of the normal rabbit epithelium supported by a well-vascularized collagen and smooth muscle backing. Preputial free onlay grafts maintained a keratinizing squamous cell epithelium with a poor supportive backing, which resulted in the formation of urethral diverticulum.

CONCLUSIONS

SIS onlay patch grafts for urethroplasty promote rabbit urethral regeneration.