[Urethral implantation of collagen in the treatment of urinary incontinence. Comparison of transurethral and periurethral approach].

Background: In mini-invasive surgery for the treatment of urinary incontinence injectable substances such as politef, autologous fat or bovine collagen, which can increase urethral resistance or support the sphincteric one are particularly used. It's a simple procedure in which patients may undergo local anesthesia, in short time and in "day hospital" regimen. Collagen, used as an injectable bulking agent, is the gold standard for this surgical technique because of complete biocompatibility, no evidences of adverse immunogenic effects, foreign-body reaction, migration of injected material, and because of higher fluidity which allows the use of thin needles compared to Politef (polytetrafluoroethylene) where an injection device is requested. Bovine collagen is partially reabsorbed within 24-36 months and a reinjection is often necessary. Although autologous fat is cheaper than bovine collagen, its injection shows more difficulties due to the need of higher needle diameter and time to store and prepare the material to inject.

Methods: The results obtained by two different approaches: transurethral injection of collagen and periurethral injection of collagen have been studied. A total of 48 patients underwent collagen injection for treatment of urinary incontinence: 24 treated by transurethral approach and 24 by periurethral approach. Follow-up at 6, 12, 24 months after treatment includes: objective exam, PAD test, functional evaluation, complete urodynamic evaluation (uroflow, cystomanometry, LPP, pressure/flow study, UPP).

Results: No clinical differences between peri/trans-urethral approach were found although collagen injection via transurethral technique need fewer material, reducing cost of treatment: an efficacy of treatment in 80% of patients and restoration of a complete urinary continence in 50% of patients was obtained. Although no clinical differences were demonstrated between the two different sites of injection, transurethral approach can be used similarly in both sexes even if without a modified resector as "injection device" it's more difficult to inject collagen in the right position, at the level of bladder neck submucosa. Perineal approach, exclusive of female sex, realizes the procedure without bleeding of urethral mucosa and no waste of collagen, though a longer period of training by surgeon is requested. After four years of experience the authors agreed that with an adequate injection device (modified resector), transurethral approach should be preferred, thus depending on the possibility to inject collagen in a correct position, just under bladder neck mucosa, which is possible to manage with this technique, in order to reduce reabsorption process of collagen and to obtain a longer efficacy of treatment reducing the number of reinjection and of course the cost of treatment. Collagen injection should be considered within an integrated therapeutical picture together with topic and systemic pharmacotherapy, physiotherapy, not excluding surgery techniques such as implantation of an artificial sphincter device in man or a sling procedure in woman.

Conclusions: The urethral collagen injection for the treatment of urinary incontinence is a safe, durable and valid technique to improve urinary continence through a non obstructive effect increasing urethral resistance. Performed under local anesthesia this procedure allows the treatment of patients who may not be candidates suitable for general anesthesia and conventional surgery.