Suburethral polypropylene (PP) mesh tapes were introduced into clinical use for stress urinary incontinence (SUI) without prior evaluation in anatomically relevant animal models, resulting in significant complications. The ewe, with its anatomical similarity to the human female pelvis, has since been adopted as a model for pelvic organ prolapse studies (1). However, its use for modeling suburethral sling implantation remains underutilized. This study aims to establish a large animal model that closely replicates the suburethral placement of support materials used in the treatment of SUI, enabling the evaluation of both clinically approved and novel biomaterials (2-3).

Adult ewes (30–40 kg) underwent surgery under general anesthesia. Positioned in lithotomy, a 12F catheter was introduced, followed by a ventral vaginal wall incision and bilateral retropubic dissection to create space for implantation. Five ewes received implants made of electrospun polyurethane (PU). Each implant had Prolene 1/0 sutures threaded through lateral suture holes and anchored retropubically; two additional sutures fixed the implant in position. Surgical sites were closed, and the catheter was removed. A Betadine-soaked vaginal pack was applied for 24 hours postoperatively. An additional five ewes received transvaginal PP mesh implants using identical dissection steps but without fixation sutures. All animals were monitored for postoperative pain, complications, and allowed free access to food and water.

Seven ewes with a mean weight of 27.7 ± 5.1 Kg underwent surgery (Fig. 1). There were no complications or morbidity directly attributable to the surgical procedure. All animals tolerated the surgery and exhibited normal eating behavior, bowel movements, and urination in the days following the operation. There was no vaginal bleeding after removal of the pack. All the animals survived to the endpoint. Examination of the vagina at harvest time showed good healing of the vaginal incision. There was no erosion or palpable mesh (Fig. 2).

This surgical approach enables suburethral placement of graft-like materials between the vaginal wall and urethra via the retropubic route, closely mirroring the technique used in women undergoing PP sling procedures. This validated ewe model offers a robust and anatomically relevant platform for preclinical evaluation of emerging materials designed for SUI treatment.

1.	Urbankova I, et al. Transvaginal Mesh Insertion in the Ovine Model. J Vis Exp JoVE. 2017 Jul 27;(125).
2.	Chapple CR, et al. Application of Tissue Engineering to Pelvic Organ Prolapse and Stress Urinary Incontinence. Low Urin Tract Symptoms. 2015 May;7(2):63–70.
3.	Hympánová L, et al. Assessment of Electrospun and Ultra-lightweight Polypropylene Meshes in the Sheep Model for Vaginal Surgery. Eur Urol Focus. 2020 Jan 15;6(1):190–8.