Development of a clinically relevant preclinical animal model to mimic suburethral implantation of support materials for stress urinary incontinence

Background

Following the severe complications widely reported in some women following polypropylene suburethral mesh implantation for the treatment of stress urinary incontinence, it has become clear that careful preclinical study in an appropriate animal model is essential. The preclinical model described here allows the postoperative clinical and histochemical assessment of material implanted in the sheep vagina and represents a model that allows prediction of the potential vaginal tissue responses to suburethral mesh implantation before implantation into humans.

Objectives

To develop and evaluate a relevant preclinical animal model to mimic suburethral implantation of support materials for stress urinary incontinence.

Material

Fourteen parous ewes of 30–40 kg were used. Under general anesthetic, animals were placed in the lithotomy position. A 12-French Foley catheter was inserted. The ventral vaginal wall was longitudinally incised. The space between the vaginal wall and the urethra was developed, with lateral retropubic dissection. Either a standard transvaginal polypropylene tape (seven animals) or a fascia mimetic microfibre spun polyurethane tape (seven animals) were inserted using an introducer either via a suprapubic (seven animals) or a transvaginal approach (seven animals) into the suburethral and retropubic space. The incisions were closed, and the catheter was removed. A betadine vaginal pack was placed and removed after 24 h. Postoperatively, the animals were observed carefully for pain and complications and allowed access to water and food under continuous veterinary supervision adhering to USA-approved protocols.

Results

On the second postoperative day, all the animals passed urine freely and had regular bowel motions. No procedure related complications were observed.

Conclusion

This is the first large animal model which has been designed for suburethral implantation. and which can be effectively used for the preoperative evaluation of novel materials designed for suburethral implantation. We believe that this technique in this large animal model accurately reproduces the surgical technique used to treat stress urinary incontinence in women. It provides a new and effective in vivo model for the objective evaluation of new materials to treat female stress incontinence.