ICS 2018: Feasibility of Sheep Animal Model for Mid-urethral Sling Surgeries

Philadelphia, PA (UroToday.com) Dr. Hijaz and his team tested and reported a survival surgery on sheep as a large animal for transvaginal sling as the training model. They used eight Dorset retired breeder, female ewes (160-175 pounds). Under general anesthesia, ewes have been positioned on their backs (dorsal recumbency) to mimic lithotomy position. After skin and vaginal surgical preparations, relevant vaginal and abdominal dimensions were reported (Figure 2). They measured clitoral dimensions, labia majora length, vaginal length, perineum length, the width of the vagina when opened using self-retaining retractors and stays and length of symphysis pubis (Figure 2).  A disposable tape measure was used for all measurements for making the comparison.

They also used human-sized slings and trocars for implantation (e.g. Lynx™ Suprapubic Mid-Urethral Sling System, Boston Scientific, MA, USA). Using the sterile instruments, surgery was mimicking human TVT procedure. Sterile Foley’s 12F urethral catheter was inserted (Figure 1a). We did a 3 cm incision in the anterior vaginal wall, 1 cm below the urethral meatus. Dissection was done bilaterally to reach out to the endopelvic fascia. Two suprapubic 1 cm-size skin incisions 5 cm-apart and located 7 cm above the pubic symphysis of the animal. The trocars traveled through the suprapubic incisions on each side in a downward motion with surgeon's forefinger acting as a guide (from the vagina) during insertion from the suprapubic region to the vagina (Figure 1d). The trocars passed through each incision, through the retropubic space, hugging the posterior aspect of the symphysis pubis, then perforating the endopelvic fascia and exiting through the already made vaginal incision. Cystoscopy was done to ensure that the bladder and urethra are not injured (figure 1b and 1c). Ewes urethra accommodated up to 16Fr. cystoscopy sheath. The sling was hooked to the trocars. The trocars on both sides were pulled to the suprapubic skin incision, placing the sling under the urethra without tension (figure 1e). Closure of vaginal incisions was done using 2-0 absorbable sutures (figure 1f). Animals’ intraoperative and postoperative follow up charts were recorded.
UroToday ICS2018 Sheep Animal Model for Mid urethral Sling Surgeries
The authors reported that the sheep vaginal anatomy was feasible to perform the placement of human-sized sling devices and surgical instruments. However, average vaginal dimensions were less than human. Mean vaginal length of sheep was 8.4 cm (figure 2b) compared to the reported 9.6 cm in human2. All average measurements are shown in figure 1d. The mean symphysis pubis’ length was 6.7 cm which is longer than reported human symphysis pubis (from 2.6 to 4.6 cm 3).  Higher abdominal incisions (6 cm above the pubic bone) was needed to accommodate the trocar curvature with the lengthy symphysis pubis without injuring the internal abdominal organs. Mean operative time was 44 ±12 minutes. Blood loss was less than 50 cc. All ewes survived the surgery and recovered smoothly. All animals urinated normally without haematuria or obstruction since the first postoperative day. After two weeks, Incisions were healed without signs of erosions, infection or rejection.

UroToday ICS2018 Sheep Animal Model for Mid urethral Sling Surgeries 2

Presented by: Ahmed Khalifa, MD from the Urology Department, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH, USA, and Menoufia University, Egypt
Co-Authors: Sali I1, Khalifa A O2, Shankar S3, Dannemiller S4, Horne W4, Evancho-Chapman M5, Akkus O6, Hijaz A K1
Author Affiliation: 1. Urology Department, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH, USA., 2. Urology Department, University Hospitals Cleveland Medical Center, Case Western Reserve University, Cleveland, OH, USA, and Menoufia University, Egypt, 3. University Hospitals Cleveland Medical Center, Cleveland, OH, USA., 4. Comparative Medicine Unit, Northeast Ohio Medical University, Rootstown, OH, USA, 5. Northeast Ohio Medical University, Rootstown, OH, USA and Summa Center for Preclinical Research and Surgical Skills Training, Summa Health System, Akron, OH, USA, 6. Dept. of Mechanical and Aerospace Engineering, Biomedical Engineering and Orthopaedics, Case Western Reserve University, Cleveland, OH, USA  

Written by: Bilal Farhan, MD; Clinical Instructor, Female Pelvic Medicine and Reconstructive Surgery, University of California, Irvine Medical Center, Twitter: @Bilalfarhan79 at the 2018 ICS International Continence Society Meeting - August 28 - 31, 2018 – Philadelphia, PA USA
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