Treatment of recurrent posterior and bulbar urethral strictures with expandable metallic stents

Buccal mucosal graft urethroplasty in five male dogs with penile urethral stricture at the bulbus glandis

OBJECTIVES

To evaluate the feasibility of correcting penile urethral strictures at the bulbus glandis using buccal mucosal graft (BMG) urethroplasty in dogs.

STUDY DESIGN

Prospective clinical trial.

ANIMALS

Five male dogs with urethral strictures located at the bulbus glandis.

METHODS

Urethrotomy was performed throughout the entire length of the urethral stricture including ~0.5 cm healthy urethra proximal and distal. The scarred tissue and unhealthy mucosa of the strictured urethra were completely excised. The graft was harvested from the buccal mucosa and tubularized at the stricture site using a urethral catheter as the skeleton. The catheter was maintained for 14 days after surgery and removed when no urethral leakage was identified on a positive-contrast retrograde urethrogram. The dogs were discharged after spontaneous urination was confirmed. Six months postoperative follow-up was completed for all dogs with repeated positive contrast urethrogram and an owner questionnaire to score urinary function and quality of life.

RESULTS

The five dogs recovered well following surgery and only one dog experienced a minor complication. All dogs were able to urinate normally after catheter removal. No evidence of leakage was identified on a 14 day postoperative retrograde positive contrast urethrogram and clinically at a median follow-up time of 182 days (range, 182-186). All owners scored the urinary function as excellent and ranked their satisfaction very high 6 months after the procedure.

CONCLUSION

Buccal mucosal graft urethroplasty has positive outcomes for dogs with penile urethral strictures.

Covered, retrievable, expandable urethral nitinol stent: feasibility study in dogs

PURPOSE

To evaluate the feasibility of using a retrievable urethral stent and to evaluate whether granulation tissue resolves after stent removal in a canine urethra.

MATERIALS AND METHODS

Polyurethane-covered retrievable 0.10-mm-thick (n = 11) or 0.15-mm-thick (n = 10) nitinol wire stents were placed in the urethras of 20 dogs. In one dog, a second stent was placed in the urethra because of complete migration of the first stent into the urinary bladder. The stents were removed with retrieval hook wires 4 weeks (n = 10) and 8 weeks (n = 10) after placement. Fourteen dogs were sacrificed just after stent removal, and the other six dogs were sacrificed 2 weeks after stent removal. Information concerning procedure success, stent migration, and tissue response was obtained.

RESULTS

Stent placement was technically successful in all dogs. Follow-up urethrograms showed partial (n = 4) or complete (n = 1) stent migration. Stent removal failed in two dogs due to partial or complete migration. Granulation tissue was observed at both ends of the stent in 17 dogs. Urethrograms and urethral specimens obtained 2 weeks after stent removal showed diminished granulation tissue and decreased thickness of the papillary projections of the epithelium compared with results obtained immediately after stent removal.

CONCLUSION

Although some design modifications are necessary to reduce current complications, the polyurethane-covered retrievable nitinol stent seems feasible for use in the urethra. Stent-induced granulation tissue formation improved after stent removal.

Nonvascular stents

Stents or endoprostheses have evolved since their introduction. Initially used only in the vascular system, the use of stents has expanded to use in the biliary, urinary, and gastrointestinal tracts and in the tracheo-bronchial tree. Current use of stents includes treatment of both benign and malignant conditions, with the greatest impact in the palliation of malignant strictures. The biomechanics and types of stents used in each region is reviewed. The indications, insertion techniques, results, and complications of stents in each of the aforementioned regions are also reviewed.