Patch Urethroplasty Using a Fascia lata Autograft in Male Rabbits

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.

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.

Fascial patch technique for repair of complicated urethrovaginal fistula

INTRODUCTION

The operative repair of urethrovaginal fistula due to tension-free vaginal tape (TVT) erosion is a challenging task, and coexisting stress urinary incontinence may complicate the situation even further. We present our technique for the repair of recurrent urethrovaginal fistula combined with stress urinary incontinence, occurring after previous removal of an eroded TVT and failed repair of the fistula.

TECHNICAL CONSIDERATIONS

With the patient in the dorsal lithotomy position, an inverted U-shaped incision was cut in the anterior vaginal wall, and a vaginal flap was developed. The Martius flap from the previous repair was identified and separated from the urethra, thereby disclosing a large fistula hole on the left side of the mid-urethra. Because the periurethral tissues were very friable and attenuated, only one-layer closure of the fistula hole with these tissues was feasible. Therefore, we opted to combine a pubovaginal fascial sling with a fascial patch graft, used to reinforce the fistula site. Through a low transverse abdominal incision, a 15 x 2-cm strip of rectus fascia was harvested. A 2 x 2-cm patch of fascia was excised from the strip and transfixed to the periurethral tissues, covering the sutured fistula site. The Martius flap was repositioned over the flap, and a pubovaginal sling procedure was done. The postoperative course was uneventful, the fistula has healed, and the patient regained full continence.

CONCLUSIONS

This technique can be used in complicated urethrovaginal fistula repair when the surrounding periurethral tissues have been devastated and can be combined with pubovaginal fascial sling placement.

A comparison of free skin graft, fascia lata, alloderm, bovine pericardium and primary repair in urethrocutaneous fistulas without diversion: an experimental study

The purpose of this study is to compare primary repair procedure with those that use bio-concordant materials in the treatment of urethrocutaneous fistula. Twenty-five New Zealand rabbits were randomly placed into five groups (primary repair, free graft, allograft fascia lata, alloderm and bovine pericardium repair groups). A single dose of 20 mg/kg of ceftriaxon was applied intramuscularly as a prophylactic dose. Urethrocutaneous fistula was formed on midpenile level. Later, while primary repair was applied in one group, repair with free grafts and with other bio-concordant materials were performed in other groups. Urinary diversion was not used in any of the rabbits. The macroscopic observation was evaluated with urethrography obtained 21 days after the operation and then the rabbits were sacrificed. A total point was obtained by awarding a point to each good parameter in the histopathological evaluation and all the groups were compared. The urethrographic findings and macroscopic examinations were normal in all groups. In histopathological examinations, ranging from the best to worst results, bovine pericardium group (8 points) had a better total score than primary repair group (7 points), allograft fascia lata group (7 points) and alloderm group (7 points). The free graft group had the worst total point (6 points). Bio-concordant materials can be used in urethrocutaneous fistula repair as an alternative to primary repair or to the grafts obtained from body tissues.

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.