A Novel Surgical Technique in a Sheep Model for Suburethral Graft Implantation

Summary

This article explains a new animal model designed for testing suburethral graft materials. In this model, a mesh tape is implanted through a vaginal incision in ewes, and the animals are observed over a three-month period. This model is essential as it lays the foundation for experimental research on grafts.

Abstract

Suburethral polypropylene mesh tapes for women were initially introduced into clinical practice for the treatment of stress urinary incontinence without being tested in an appropriate animal model. The goal of this work has been to establish and evaluate a suitable animal model for the assessment of suburethral tape grafts. Allowing for the anatomical similarities between ewes and women and recognizing the inevitable differences in posture, but recognizing prior work, this report presents a step-by-step description of the surgery involved in an animal model that simulates the implantation of support materials for treating stress urinary incontinence in women. Seven ewes with a mean weight of 27.7 SD 5.1 kg underwent surgery. In the lithotomy position, a ventral vaginal wall incision was made. In five animals, using an introducer, a polyurethane implant was placed underneath the urethra and fixed with absorbable sutures. The incision was closed, and a betadine vaginal pack was placed after 24 h. Two animals received transvaginal polypropylene mesh using similar surgical steps but no fixation sutures. After surgery, all animals urinated freely and had regular bowel movements. No animals showed signs of vaginal erosion or graft infection during the three-month follow-up. This large animal model accurately reproduces the surgical technique used in women, thereby providing a valuable platform for evaluating new materials for stress urinary incontinence treatment.

Introduction

Stress urinary incontinence (SUI) affects 26% of women in a USA prevalence study; in addition, 16% more women have both stress and urgency incontinence¹. Tension-free vaginal tape evolved as a less morbid surgical treatment for SUI associated with a comparable success rate and faster recovery than the gold standard colposuspension^2,3. However, suburethral polypropylene (PP) mesh tapes were introduced without testing in a relevant animal model, leading to adverse responses^4,5. In recent years there have been reports of significan....

Protocol

The hospital's Institutional Review Board (IRB) and the Animal Care and Use Committee reviewed and granted approval for the protocol (ethics approval number: 2230017). This approval adheres to internationally accepted principles of humane experimental techniques. All procedures and postoperative care were conducted in a facility accredited by the Association for Assessment and Accreditation of Laboratory Animal Care (AAALAC).

Ensure that qualified veterinarians always conduct medical management and anesthesia.

1. Animal preparation and anesthesia

1. In the preoperative room, give the....

Results

Seven ewes with a mean weight of 27.7 SD 5.1 Kg underwent surgery (Table 1). Figures 1-2 show the surgical procedure. There were no complications or morbidity directly attributable to the surgical procedure. All animals tolerated the surgery and exhibited normal eating behavior, bowel movement, and micturition in the next postoperative days. There was no vaginal bleeding after removal of the pack. All the animals survived to the endpoint. During the follow-up, none of the animals exhibit.......

Discussion

The critical step in the current study is to dissect a plane between the vagina and urethra, develop a retropubic passage, guide a trocar-mounted graft cranially through this plane, and lay the graft in a suburethral position. This animal model effectively simulates the implantation of suburethral mesh in women, making it a unique tool for surgical experimentation^2,16. Although there are previous experiments evaluating the PP mesh as a possible synthetic graft fo.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Advantage Fit Blue System (polypropylene tape)	Boston Scientific Corporation 300 Boston Scientific Way Marlborough, MA 01752	M0068502120	Needle diameter: 2.7mm, Mesh thickness: 0.66 mm, Pore size: 1182 μm, Fiber size (diameter): 0.15 mm
COVIDIEN Nellcor MAXA	Covidien Medtronic, Operational Headquarters 710 Medtronic Parkway, Minneapolis, MN 55432-5640 USA		Pulse oxymeter
COVIDIEN Shiley Hi-Lo Oral/Nasal Tracheal Tube	Covidien Medtronic, Operational Headquarters 710 Medtronic Parkway, Minneapolis, MN 55432-5640 USA		Endotriacheal tube 7 mm ID
Drager Fabius	Draeger Arabia Co.Ltd. P.O.Box 365642. Riyadh 11393 Kingdom of Saudi Arabia.		Anesthesia machine and monitors, Siemens SC 7000 monitor, vaporizers , flowmeters for oxygen, air and nitrous oxide.
Electrospun polyurethane fascio-mimetic implant	University of Sheffield, Sheffield, United Kingdom.	NA	Graft material in a tape shape.
Polypropylene suture	Johnson & Johnson Medical N.V., Belgium	V8015	2.0 suture on rounded needle
Sterile procedure pack	Arabian Medical Manufacturing Company , P.O. Box 355033, Riyadh, 11383, Saudi Arabia	CPT-01000-022	Povidone iodine tray, includes Povidone iodine 7.5% 120 ml, Povidone iodine 10% 120 ml, applicator sponges, sterile towels.