Comparison of the precision of transurethral endoscopic versus ultrasound-guided application of injectables.

Objective: To compare the precision of transurethral endoscopic- vs ultrasound (US)-guided injections, as transurethral application of various injectables under endoscopic view are widely used to treat urinary incontinence.

Material And Methods: Bovine collagen was injected into the lower urinary tract in 20 dead female pigs. In each pig five depots of collagen were injected and there were five pigs in each group. In group I collagen was injected into the urethral wall under endoscopic control. In group II collagen depots were injected periurethrally under endosocopic guidance. In group III collagen was injected into the urethral wall under US control. In group IV collagen depots were injected periurethrally under US guidance. A transurethral US probe (6 F, 15 MHz) and injection device were used for transurethral US-guided injections. In all pigs the urethra and the periurethral tissue were removed after injection and investigated using anatomical preparations and histological sections.

Results: In group I only two collagen depots were actually located in the urethral wall in two pigs (two of 25 depots, 8%). In group II five depots in two pigs were located in the urethral wall (five of 25 depots, 20%). The periurethral collagen depots were found to spread out in the loose connective and fat tissue around the urethra. In group III all US-guided injections of collagen were situated in the urethral wall and in group IV they were all located periurethrally.

Conclusions: The present study shows that endoscopic application of injectables is an inaccurate technique, while US-guided injections are precise. US-guided injection enables excellent control of the therapeutic procedure.