We thank Ivan Laermans, Rosita Kinart, Ann Lissens (Centre for Surgical Technologies, KU Leuven, Leuven, Belgium). Jo Verbinnen and Kristof Reyniers (Vesalius Institute of Anatomy, Faculty of Medicine, KU Leuven, Leuven, Belgium) provided technical support during the experiment. We thank Leen Mortier for the help with data and manuscript management. We thank FEG Textiltechniken for manufacturing prototype meshes, sterilizing them, and donating them unconditionally for research.

Ethical approval for this experiment was obtained from the Ethics Committee on Animal Experimentation of the KU Leuven (P065/2013). Animals were treated in accordance with current national guidelines on animal welfare.
1. Material and the Experimental Animal
<ol>
	<li>Surgery preparation
	<ol>
		<li>In the surgical theater cover a table with a sterile drape and prepare one sterile curved trocar (Figure 1, panel A), sterile surgical instruments, sutures, and sterile gauze. Perfor...

<ol>
	<li>Glazener, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Childbirth+and+prolapse:+Long-term+associations+with+the+symptoms+and+objective+measurement+of+pelvic+organ+prolapse.">Childbirth and prolapse: Long-term associations with the symptoms and objective measurement of pelvic organ prolapse.</a> BJOG An Int. J. Obstet. Gynaecol. 120 (2), 161-168 (2013).</li><li>Jia, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+and+safety+of+using+mesh+or+grafts+in+surgery+for+anterior+and/or+posterior+vaginal+wall+prolapse:+systematic+review+and+meta-analysis.">Efficacy and safety of using mesh or grafts in surgery for anterior and/or posterior vaginal wall prolapse: systematic review and meta-analysis.</a> BJOG. 115 (11), 1350-1361 (2008).</li><li>Maher, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transvaginal+mesh+or+grafts+compared+with+native+tissue+repair+for+vaginal+prolapse.">Transvaginal mesh or grafts compared with native tissue repair for vaginal prolapse.</a> Review. 2 (2), 10-13 (2016).</li><li>Nieminen, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Outcomes+after+anterior+vaginal+wall+repair+with+mesh:+a+randomized,+controlled+trial+with+a+3+year+follow-up.">Outcomes after anterior vaginal wall repair with mesh: a randomized, controlled trial with a 3 year follow-up.</a> Am. J. Obstet. Gynecol. 203 (3), e1-e8 (2010).</li><li>Abramowitch, S. D., Feola, A., Jallah, Z., Moalli, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tissue+mechanics,+animal+models,+and+pelvic+organ+prolapse:+a+review.">Tissue mechanics, animal models, and pelvic organ prolapse: a review.</a> Eur. J. Obstet. Gynecol. Reprod. Biol. 144, S146-S158 (2009).</li><li>Couri, B., Lenis, A., Borazjani, A., Paraiso, M. F. R., Damaser, M. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+female+pelvic+organ+prolapse:+lessons+learned.">Animal models of female pelvic organ prolapse: lessons learned.</a> Expert Rev. Obs. Gynecol. 7 (3), 249-260 (2012).</li><li>Deprest, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biology+behind+fascial+defects+and+the+use+of+implants+in+pelvic+organ+prolapse+repair.">The biology behind fascial defects and the use of implants in pelvic organ prolapse repair.</a> Int. Urogynecol. J. Pelvic Floor Dysfunct. 17, S16-S25 (2006).</li><li>Ozog, Y., Mazza, E., De Ridder, D., Deprest, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechanical+effects+of+polyglecaprone+fibers+in+a+polypropylene+mesh+after+abdominal+and+rectovaginal+implantation+in+a+rabbit.">Biomechanical effects of polyglecaprone fibers in a polypropylene mesh after abdominal and rectovaginal implantation in a rabbit.</a> Int. Urogynecol. J. 23 (10), 1397-1402 (2012).</li><li>Manodoro, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Graft-related+complications+and+biaxial+tensiometry+following+experimental+vaginal+implantation+of+flat+mesh+of+variable+dimensions.">Graft-related complications and biaxial tensiometry following experimental vaginal implantation of flat mesh of variable dimensions.</a> BJOG. 120 (2), 244-250 (2013).</li><li>Endo, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cross-linked+xenogenic+collagen+implantation+in+the+sheep+model+for+vaginal+surgery.">Cross-linked xenogenic collagen implantation in the sheep model for vaginal surgery.</a> Gynecol. Surg. , 113-122 (2015).</li><li>Feola, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Host+reaction+to+vaginally+inserted+collagen+containing+polypropylene+implants+in+sheep.">Host reaction to vaginally inserted collagen containing polypropylene implants in sheep.</a> Am. J. Obstet. Gynecol. 212 (4), e1-e474 (2015).</li><li>Barnhart, K. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Baseline+dimensions+of+the+human+vagina.">Baseline dimensions of the human vagina.</a> Hum. Reprod. 21 (6), 1618-1622 (2006).</li><li>Tayrac, R., Alves, A., Th&#233;rin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collagen-coated+vs+noncoated+low-weight+polypropylene+meshes+in+a+sheep+model+for+vaginal+surgery.+A+pilot+study.">Collagen-coated vs noncoated low-weight polypropylene meshes in a sheep model for vaginal surgery. A pilot study.</a> Int. Urogynecol. J. Pelvic Floor Dysfunct. 18 (5), 513-520 (2007).</li><li>Sobiraj, A., Busse, G., I, H. B. O. S. E. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ivastigation+into+the+blood+plasma+profiles+progesterone+in+sheep+sufferingform+vaignal+inversion+and+prolapse.">Ivastigation into the blood plasma profiles progesterone in sheep sufferingform vaignal inversion and prolapse.</a> Br. Vet. J. 142 (142), 218-223 (1986).</li><li>Reisenauer, C., Kirschniak, A., Drews, U., Wallwiener, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomical+conditions+for+pelvic+floor+reconstruction+with+polypropylene+implant+and+its+application+for+the+treatment+of+vaginal+prolapse.">Anatomical conditions for pelvic floor reconstruction with polypropylene implant and its application for the treatment of vaginal prolapse.</a> Eur. J. Obstet. Gynecol. Reprod. Biol. 131, 214-225 (2007).</li><li>Carey, M., Slack, M., Higgs, P., Wynn-Williams, M., Cornish, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vaginal+surgery+for+pelvic+organ+prolapse+using+mesh+and+a+vaginal+support+device.">Vaginal surgery for pelvic organ prolapse using mesh and a vaginal support device.</a> BJOG An Int. J. Obstet. Gynaecol. 115 (3), 391-397 (2008).</li><li>Urbankova, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+anatomy+of+the+ovine+and+female+pelvis.">Comparative anatomy of the ovine and female pelvis.</a> Gynecol. Obstet. Invest. , (2016).</li><li>Maurer, M. M., R&#246;hrnbauer, B., Feola, a., Deprest, J., Mazza, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+biocompatibility+of+prosthetic+meshes:+A+comprehensive+protocol+for+mechanical+characterization.">Mechanical biocompatibility of prosthetic meshes: A comprehensive protocol for mechanical characterization.</a> J. Mech. Behav. Biomed. Mater. 40, 42-58 (2014).</li><li>Leval, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+Surgical+Technique+for+the+Treatment+of+Female+Stress+Urinary+Incontinence.">Novel Surgical Technique for the Treatment of Female Stress Urinary Incontinence.</a> Transobturator Vaginal Tape Inside-Out. Eur. Urol. 44 (6), 724-730 (2003).</li><li>Reisenauer, C., Kirschniak, A., Drews, U., Wallwiener, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transobturator+vaginal+tape+inside-out.">Transobturator vaginal tape inside-out.</a> Eur. J. Obstet. Gynecol. Reprod. Biol. 127 (1), 123-129 (2006).</li><li>Bafghi, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bowel+perforation+as+late+complication+of+tension-free+vaginal+tape.">Bowel perforation as late complication of tension-free vaginal tape.</a> J Gynecol Obs. Biol Reprod. 34 (6), 606-607 (2005).</li><li>Hinoul, P., Vanormelingen, L., Roovers, J. P., de Jonge, E., Smajda, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anatomical+variability+in+the+trajectory+of+the+inside-out+transobturator+vaginal+tape+technique+(TVT-O).">Anatomical variability in the trajectory of the inside-out transobturator vaginal tape technique (TVT-O).</a> Int. Urogynecol. J. Pelvic Floor Dysfunct. 18 (10), 1201-1206 (2007).</li><li>Schaller, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Illustrated Veterinary Anatomical Nomenclature. , (2007).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serious+Complications+Associated+with+Transvaginal+Placement+of+Surgical+Mesh+for+Pelvic+Organ+Prolapse.">Serious Complications Associated with Transvaginal Placement of Surgical Mesh for Pelvic Organ Prolapse.</a> FDA Safety Communication. , (2016).</li><li>Reinier, M., Groep, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Final+Opinion+on+the+use+of+meshes+in+urogynecological+surgery.">Final Opinion on the use of meshes in urogynecological surgery.</a> SCENIHR- European Commission. , (2016).</li></ol>

Here, we describe an experimental procedure in sheep, aimed to mimic vaginal dissection and transvaginal mesh insertion of an implant with or without anchoring arms. The subsequent steps and instruments were inspired by surgical procedures done for POP and stress urinary incontinence15,16,19,20. After initial anatomical dissections, there were still some problems during experimental mesh insert...

Pelvic organ prolapse is clinically diagnosed in half of women who had at least one vaginal delivery, but subjectively, it bothers half of women overall1. The mainstay of therapy is surgical reconstruction using either native tissue or implant materials, but each of these methods has its limitations, including recurrence or local complications2,3,4. The ideal implant has not yet been identified; hence, there is an ongoing demand for product innovation and for the development of a proper pipeline for preclinical experimentation prior to the introduction of new products and techniques to the market. One of the steps in this track is experimental evaluation on suitable animal models5,6. Ideally, they should mimic the anatomical, biomechanical, and biological environments. When it comes to the experimental evaluation of novel implants, they are typically tested first in smaller models, either for biocompatibility or for the reconstruction of abdominal wall defects. That type of experiments has been criticized, because the implants are not inserted into the area of interest (i.e., the vagina)7. Vaginal surgery models are more scarce, certainly when the goal of the experiment is to document the biomechanical characteristics of explants. For this reason, there was a move from rabbits to sheep8. Adult ewes are large-animal models with a reasonably sized and accessible vagina. They can be used for the mid-term evaluation of novel implants, and it is possible to reproduce vaginal exposures with certain materials9,10,11,12,13. Not only the dimensions and anatomy of the ovine vagina and pelvic floor are comparable to those in humans, but also the spontaneous occurrence of prolapse, which occurs in 15% of ewes. Prolapse risk factors are overlapping (i.e., multiparity, previous history of POP, increased intra-abdominal pressure induced by a higher bodyweight or when grazing on hills, and comparable effects of (phyto)estrogens)6,14. In Europe, sheep are the only reasonable alternative, as research on non-human primates has been nearly completely banned. Here, the model was taken one step further by mimicking the transvaginal insertion of implants using trocars and guides for the tension-free placement of meshes into the recto-vaginal septum. This was followed by fixing the implant using anchoring with arms through the ligaments of muscles, which can be considered equivalent to clinical practice15,16. So far, this technique has not been studied, though many believe that specific complications may occur due to the use of these longer strips and/or the piercing of anatomical structures.
In an earlier detailed anatomical study, the ovine pelvic floor was compared to the female pelvis17. When it comes to anchoring the implant, sheep do not have the sacrospinous ligament, yet they do have a very well-developed and broad sacrotuberous ligament. The pudendal nerve runs ventrally over it, making it unsafe to use this landmark as a suspension point. Conversely, the coccygeus muscle and its fascia, as well as the obturator membrane, are accessible through the rectovaginal space. Here, the access and position of the anatomical structures for the fixation of anchoring arms is proposed. The instruments that can be used to position the mesh are discussed. Finally, the relationship of the arms or trocars to adjacent anatomical structures, such as vessels and nerves, as well as potential intraoperative complications, are also described.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Animals:&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>parous female sheep (45 - 65 kg)</td>
			<td>Zo&#246;technical Institute of the KU Leuven</td>
			<td>NA</td>
			<td>experimetnal animal</td>
		</tr>
		<tr>
			<td>Sterile clothing:&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>sterile drape 45 x 75 cm</td>
			<td>Lohmann &#38; Rauscher, Regensdorf, Germany</td>
			<td>33002</td>
			<td>other material</td>
		</tr>
		<tr>
			<td>sterile OR drape 150 x 180 cm</td>
			<td>Lohmann &#38; Rauscher, Regensdorf, Germany</td>
			<td>33009</td>
			<td>other material</td>
		</tr>
		<tr>
			<td>sterile glowes 2x</td>
			<td>Lohmann &#38; Rauscher, Regensdorf, Germany</td>
			<td>16652</td>
			<td>other material</td>
		</tr>
		<tr>
			<td>sterile surgical gown 2x</td>
			<td>Lohmann &#38; Rauscher, Regensdorf, Germany</td>
			<td>19342</td>
			<td>other material</td>
		</tr>
		<tr>
			<td>surgical head cap 2x</td>
			<td>Lohmann &#38; Rauscher, Regensdorf, Germany</td>
			<td>17427</td>
			<td>other material</td>
		</tr>
		<tr>
			<td>surgical face mask 2x</td>
			<td>Lohmann &#38; Rauscher, Regensdorf, Germany</td>
			<td>11983</td>
			<td>other material</td>
		</tr>
		<tr>
			<td>Other surgical material</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>implant</td>
			<td>FEG Textiltechnik GmbH, Aachen, Germany</td>
			<td>NA</td>
			<td>purposely designed implant</td>
		</tr>
		<tr>
			<td>3/0 polypropylene suture</td>
			<td>Prolene, Ethicon, Diegem, Belgium</td>
			<td>8762H</td>
			<td>suture material</td>
		</tr>
		<tr>
			<td>3/0 polygecaprone suture</td>
			<td>Vicryl, Ethicon</td>
			<td>J311H</td>
			<td>suture material</td>
		</tr>
		<tr>
			<td>gauze swabs 10 x 10 cm 10x, 12-ply</td>
			<td>Lohmann &#38; Rauscher, Regensdorf, Germany</td>
			<td>11574</td>
			<td>other material</td>
		</tr>
		<tr>
			<td>syringe 20 mL</td>
			<td>Becton Dickinsosn S.A., Madrid, Spain</td>
			<td>300613</td>
			<td>aqua-dissection</td>
		</tr>
		<tr>
			<td>needle 16 gauge</td>
			<td>Terumo, Leuven, Belgium</td>
			<td>NN-2238R</td>
			<td>aqua-dissection</td>
		</tr>
		<tr>
			<td>Surgical equipment:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>blade no.22</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>10022-00</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Allis tissue forceps 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>11091-15</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Standart pattern forceps 1x2 theeth 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>11023-14</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Standart pattern forceps straight serrated 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>11000-14</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Scalpel handle 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>10004-13</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Halstead-Mosquito forceps 2x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>13008-12</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Standart pattern scissors 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>14001-14</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Metzenbaum scissors 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>14016-18</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Crile Wood needle holder 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>12003-15</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Kell forceps 1x</td>
			<td>Fine science isntruments, Heidelberg, Germany</td>
			<td>13018-14</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Long Starr Self-Retaining Retractor with eight 5mm sharp stay hooks</td>
			<td>Cooper Surgical, Tumbull, USA</td>
			<td>3704</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Heaney Simon Vaginal Retractor</td>
			<td>Medical supplies &#38; equipments co., Katy, Texas, USA</td>
			<td>403-129FSI</td>
			<td>surgical instruments</td>
		</tr>
		<tr>
			<td>Trocar (Insnare)</td>
			<td>Bard, West Sussex, United Kingdom</td>
			<td>NA</td>
			<td>any trocar on market for transvaginal mesh implantation</td>
		</tr>
		<tr>
			<td>Medication:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>amoxilicilline clavulanate 1000mg / 300 mL (Ampiciline)</td>
			<td>GSK, Wavre, Belgium</td>
			<td>NA</td>
			<td>antibiotics</td>
		</tr>
		<tr>
			<td>buprenorfin 0.3 mg/mL + chlorocresol 1.35 mg/mL (Vetregesic)</td>
			<td>Ecuphar, Oostkamp, Belgium</td>
			<td>NA</td>
			<td>analgesia</td>
		</tr>
		<tr>
			<td>ketamin HCL 100mg/mL (Ketamine 1000)</td>
			<td>Ceva Sante Animale, Brussels, Belgium</td>
			<td>NA</td>
			<td>anesthesia</td>
		</tr>
		<tr>
			<td>isoflurane (IsoFlo)</td>
			<td>Abbott Laboratories Ltd, Maidenhead, Berkshire, UK</td>
			<td>NA</td>
			<td>anesthesia</td>
		</tr>
		<tr>
			<td>polyvidone iodium 7.5% (Braunol)</td>
			<td>B. Braun Medical, Machelen, Belgium</td>
			<td>NA</td>
			<td>local desinfection</td>
		</tr>
		<tr>
			<td>saline solution 500ml</td>
			<td>B. Braun Medical, Machelen, Belgium</td>
			<td>NA</td>
			<td>aqua-dissection</td>
		</tr>
		<tr>
			<td>Xxylazine HCl , 1 mL/50 kg&#160;</td>
			<td>Vexylan, Ceva Sante Animale, Belgium</td>
			<td>NA</td>
			<td>premedication</td>
		</tr>
		<tr>
			<td>atropine Sulfate 15 mg/ml (),</td>
			<td>Viatris, Belgium</td>
			<td>NA</td>
			<td>premedication</td>
		</tr>
	</tbody>
</table>

transvaginal mesh insertion in the ovine model

This protocol describes mesh insertion into the rectovaginal septum in sheep using a single vaginal incision technique, with and without the trocar-guided insertion of anchoring arms. Parous sheep underwent the dissection of the rectovaginal septum, followed by the insertion of an implant with or without four anchoring arms, both designed to fit the ovine anatomy. The anchoring arms were put in place using a trocar and an "outside-in" technique. The cranial arms were passed through the obturator, gracilis, and adductor magnus muscles. The caudal arms were fixed near the sacrotuberous ligament, through the coccygeus muscles. This technique allows for the mimicking of surgical procedures performed in women suffering from pelvic organ prolapse. The anatomical spaces and elements are easily identified. The most critical part of the procedure is the insertion of the cranial trocar, which can easily penetrate the peritoneal cavity or the surrounding pelvic organs. This can be avoided by a more extensive retroperitoneal dissection and by guiding the trocar more laterally. This approach is designed only for experimental testing of novel implants in large animal models, as trocar-guided insertion is currently not used clinically.

Management in a Longer Observation Setup
Following the surgical procedure, vaginal packing (a saline-solution-soaked gauze package inserted in the vagina immediately after the surgery) may be inserted for 24 h to secure the implant position. The sheep should be placed in a recovery cage and its respiratory function followed until full recovery. Later, it is possible to place the sheep in the stable and to allow ...

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Transvaginal Mesh Insertion in the Ovine Model

This protocol describes mesh implantation in the ovine rectovaginal septum using a single vaginal incision technique, with and without the trocar-guided insertion of anchoring arms.

This protocol describes mesh insertion into the rectovaginal septum in sheep using a single vaginal incision technique, with and without the trocar-guided ...

The overall goal of this experimental surgical procedure is to use a single vaginal incision to implant mesh into the recto vaginal septum, with or without trocar guided insertion of the anchoring arms. The sheep is a useful model as the ovine pelvic floor experiences similar changes to those that occur during human childbirth, and as the sheep dimensions permit comparable surgical interventions. The main advantage of this technique is that it uses a widely available non primate large animal model that makes a clinically implemented surgical approach to transvaginal implantation.Though this method can provide insight into the surgical treatment of pelvic organ prolapse with implants it can also be applied to other surgical techniques, like native tissue repair. Visual demonstration of this method is critical, as it is difficult to teach these surgical techniques without being able to observe them. After confirming that the sheep is sleepy and lethargic, place the animal in the lithotomy position on the end of the surgical table and use ropes to secure the limbs with the hips in hyperflexion.Next, push transvaginally on the bladder to empty the organ and manually empty the rectum, followed by shaving of the perineum, the medial area of the thigh, and the tail folds. Disinfect the exposed skin with 7.5%povidone iodium and after donning the appropriate personal protective equipment cover the animal with a sterile drape, with an opening above the genital hiatus. Use allis forceps to grasp the dorsal vaginal wall three centimeters cranial to the hymenal ring.Then, use a 10 milliliter syringe loaded with a 22 gauge needle to inject saline three to four millimeters under the vaginal epithelium along the mid line of the recto vaginal septum 1.5 centimeters cranial to the hymenal ring. Aqua dissect the vaginal tissue by injecting the saline into the recto vaginal septum. Then use a scalpel to make a three centimeter long mid line incision on the vaginal epithelium starting caudal to the allis forceps and ending at the hymenal ring.Hold the incision open with a self retaining retractor over the perineum and four sharp stay hooks. Then use your index to bluntly dissect the recto vaginal fascia from the vaginal wall laterally toward the pelvic side walls and cranially up to the caudal aspect of the cul-de-sac. At this point, you can insert either the rectangular implant or continue with dissection to insert the implant with anchoring arms.When a suitable space has been created for the 30 by 40 millimeter flat mesh insert a vaginal retractor into the incision and use a simple interrupted three oh polypropylene suture on the left and right sides of the most cranial aspect of the dissected recto vaginal space to suture the left and right cranial corner of the implant. Trim the residual suture material and add one additional simple interrupted suture midway along the cranial aspect of the implant. Suture the lateral edges of the implant midway onto the surrounding connective tissue, with a simple interrupted three oh polypropylene suture.Suture the left and right caudal corners with simple interrupted three oh polypropylene sutures on the left and right sides of the most caudal aspect of the recto vaginal space. Then add one additional simple interrupted suture midway along the caudal aspect of the implant, and close the vaginal incisions with a running three oh polyglactin suture, which will be shown at the end of the video. This is another operation.Alternatively, one can continue the recto vaginal space cranial ventrally to reach the medial aspect of the obturator foramen and also dissect the space caudolaterally to reach the caudally located coccygeus muscle. With a number 24 blade, make four one centimeter wide incisions on the vulvar side cutting through the skin and superficial muscular fascia. Make two ventral incisions on the medial aspect of the thigh, approximately four centimeters cranial from the caudal border of the sciatic arch, and three centimeters lateral from the midline.Make two dorsal incisions at the insertion of the tail folds two centimeters medial to the tuber ischiadicum. Then place a curved trocar through one of the ventral incisions. Controlling the progression of the trocar with a finger inserted through the vaginal incision, pass the trocar through the abductor magnus muscle, the external obturator, and the medial aspect of the obturator foramen.Take special care when pushing the trocar, as pushing the trocar in the wrong direction may cause severe injury to the vessel or nerve both of which are located in the cranial aspect of the obturator foramen. Guide the tip of the trocar to the tendonous arc of the levator ani muscle, and expose the guiding wire in the vaginal wall incision. Load the wire with the corresponding ipsilateral cranial mesh arm and pull the loaded trocar through the tissues, keeping the mesh arm tension free.Then load the guide wire with the second cranial arm through the ventral incision on the other side of the animal and pull the trocar through the tissues, as just demonstrated. Now pass the trocar through the coccygeus muscle via one of the dorsal incisions just distal to the sacrotuberous ligament, and expose the guide wire through the vaginal incision. Grasp the dorsal arm of the mesh and pull the mesh out, keeping the arm tension free.Transfer the second arm of mesh to the other side of the animal as just demonstrated, and adjust the mesh position by flattening and applying tension to both arms, while keeping the mesh tension free. Using simple interrupted three oh polypropylene sutures in the middle of the caudal borders, secure the mesh to the surrounding connective tissue. Then cut the arms at the skin, and use simple interrupted three oh poliglecaprone sutures to close all of the skin incisions, followed by a running three oh poliglecaprone suture to close the vaginal incision.In this experimental animal, the cranial arms were passed through the caudal aspect of the obturator foramen. The entry point of the trocar was at the tendonous arc of the levator ani two to 2.5 centimeters caudal to the obturator canal and the obturator vessels and nerve. The gracilis muscle was moved medially to display the course of the cranial arm through the semi tendinosis and the abductor magnus muscles.The caudal arms were passed one centimeter to caudal to the caudal aspect of the broad sacrotuberous ligament, right through the coccygeus muscle. The central part of the mesh was placed flat with its cranial section stretching retroperitoneally under the caudal end of the cul-de-sac, and its caudal section down along the recto vaginal septum. Once mastered, this type of operation can be completed in 40 minutes.Before attempting this procedure, it is important to remember to become familiar with the ovine pelvic anatomy and to obtain surgical skills, such as blunt and sharp dissection and hemostatic techniques. Following this procedure other methods like native tissue repair can be performed. After its development this technique paved the way for researchers in the field of urogynecology to explore implant augmented pelvis organ prolapse repair in an ovine model for vaginal surgery.After watching this video you should have a good understanding of how to dissect the ovine recto vaginal septum to insert a flat rectangular implant and to use trocars to guide the insertion of an arm anchored implant. Don't forget that working with sharp objects, such as scalpels or needles may cause accidental injury or infection and that precautions such as paying full attention during the surgery should always be taken while performing this procedure.

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Research

JoVE Journal

Medicine

15.9K visualizações.  Clinical Specialties Research Groups, Faculty of Medicine, KU Leuven. The overall goal of this experimental surgical procedure is to use a single vaginal incision to implant mesh into the recto vaginal septum, with or without trocar guided insertion of the anchoring arms. The sheep is a useful model as the ovine pelvic floor experiences similar changes to those that occur during human childbirth, and as the sheep dimensions permit comparable surgical interventions. The main advantage of this technique is that it uses a widely available non primate large animal ...