Int Urogynecol J DOI 10.1007/s00192-017-3313-8
ORIGINAL ARTICLE
Feasibility and benefits of the ewe as a model for vaginal surgery training Yohan Kerbage 1,2,3 & Géraldine Giraudet 2 & Chrystèle Rubod 1,2 & Charles Garabedian 1,2 & Géraldine Rivaux 2 & Michel Cosson 1,2
Received: 15 December 2016 / Accepted: 2 March 2017 # The International Urogynecological Association 2017
Abstract Introduction and hypothesis The objective was to evaluate the ewe as an animal model for teaching and training in vaginal surgery. Methods Twenty-nine postgraduate surgeons attended a training course on vaginal prolapse surgery. After a review of human and sheep anatomy, the participants performed transvaginal meshes, vaginal hysterectomy, SSLF (Richter), and OAS repair in ewes and human cadavers. Participants completed questionnaires on the whole course. Results Questionnaires showed the significant superiority of ewes over human cadavers for all items evaluated regarding surgical dissections. Only identification of the sacrospinous ligament and the spine were judged to be similar in ewes and human cadavers. Participants noticed that ewe model is appropriate for vaginal prolapse surgery training for resident and for postgraduate surgeons. Two vaginal hysterectomies were also performed. Operating time, surgery, and anatomy were nearly identical to that of humans. The same conclusions were made while performing sacrospinous ligament fixation (Richter) and obstetric anal sphincter injury repair.
Electronic supplementary material The online version of this article (doi:10.1007/s00192-017-3313-8) contains supplementary material, which is available to authorized users * Yohan Kerbage
[email protected]
1
Faculté de Médecine, Université de Lille, 59000 Lille, France
2
Service de Gynécologie-Obstétrique, CHU Lille, 59000 Lille, France
3
Department of Gynecologic Surgery, Jeanne de Flandre Hospital, CHRU de Lille, Lille, France
Conclusion This series indicates that the ewe is a useful animal model for teaching vaginal surgery. Keywords Ewes . Prolapse . Vaginal surgery . Mesh . Animal model . Training
Introduction In France, but also worldwide, the use of vaginal hysterectomy is declining, even though it is associated with superior patient outcomes and costs less than other methods of hysterectomy [1]. Current controversies on vaginal meshes are also a serious blow for vaginal surgery [2]. Although, fewer vaginal surgical procedures are performed in operating rooms; more students must be trained in a shorter period than before, mainly due to restrictions on duty hours [3]. Because of the practical facts (discomfort, poor visibility), training in vaginal surgery is also more difficult. Thus, it is necessary to find an appropriate model for teaching and perpetuating vaginal surgery. No high-fidelity simulator exists for vaginal surgery. Historically, training in surgery was carried out using human cadavers, but the main problem of non-living tissues is a lack of laxity, which is a major point in vaginal surgery. Dissection and identification of the structure is harder. There is also no bleeding. Furthermore, human cadavers are increasingly difficult to obtain. Thus, a more appropriate model is currently an animal. Couri et al. reviewed all data available on female pelvis prolapse animal model [4] and only one study has been published using an animal model for training for transobturator and retropubic sling techniques [5]. However, there is no literature on the educational purpose of these animal models. The aim of this study was to evaluate the ewe as an animal model for vaginal surgery.
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Materials and methods Three training workshops dedicated to vaginal surgery were held in 2016, in Lille University Hospital. All participants were volunteer postgraduate gynecologists or urologist surgeons from France, Germany, Portugal, Poland, and Spain. The workshops started with a theoretical course on anatomy (both human and ewes) and vaginal meshes (Uphold® and Pinnacle®, Boston Scientific Corporation®). Then, practical exercises were performed on ewes and on human cadavers. Supervisors were dedicated to guiding each group. Training was financed with both institutional (Lille University) and industrial funds (Boston Scientific Corporation®). Participants were volunteers and were not paid. Ewes Fifteen adult (between 8 and 12 years old) multiparous ewes weighing approximately 75 kg were used during the three sessions (five for each session). Surgery was performed under general anesthesia taking into account all ethics laws. Participants performed pelvic examination to palpate the bones, muscles, and ligaments of the pelvis and then performed each surgical step of vaginal surgery using mesh (Uphold® and Pinnacle® Boston Scientific Corporation®). Two ewes were dedicated to perform a vaginal hysterectomy, a sacrospinous ligament fixation (Richter), and an obstetric anal sphincter injury repair. The ewes were in the lithotomy position, in the same way that women are positioned in the operating room. Human cadavers Six human cadavers were used. Anterior and posterior dissections were performed, anterior and posterior meshes were placed. The two human cadavers necessary for each session were women who had donated their body to medical science. No ethics approval was necessary. The rules of bioethics were complied too. The Clinical Anatomy Skills Centre approved the simulation outline and the use of cadaveric material. The University of Lille supplied the cadaveric material. This was obtained through donations to the University of Lille Anatomical Bequest Program, which operates under the terms of the Anatomy Act. Questionnaire At the end of the course, an anonymous questionnaire was given to all participants. The first part was dedicated to the characteristics of the attendant (specialty, years of experience, vaginal surgery experience) and overall satisfaction of the course. The second part was the evaluation of the workshop concerning theoretical course, practical course on ewes and
human cadavers (dissection, anatomy, and surgery). The second part aimed to evaluate the lifelike qualities of the model chosen for the training. A 1–5 grading scale was used, with grade 1(low) being the lowest grade and grade 5 (excellent) the highest grade. All the supervisors answered the same questionnaire. Statistics Mean and median were calculated using Excel®. Median classes were used in our questionnaire as in our opinion, surgeons were not aware of giving precisely the number of meshes used per year. Evaluations of cadavers and the ewe model regarding surgical dissection were compared using t test. Responses to satisfaction surveys were also compared using t test. The pedagogical benefits of the ewe and cadaver models were compared using a t test. t tests were performed using R®. Statistical significance was accepted to be p < 0.05.
Results Twenty-nine postgraduate surgeons attended the three workshops that we organized. Four supervisors mentored the participants throughout the workshops. All participants and supervisors answered questionnaires. Mean age of the participant was 46 years old. They were highly experienced in vaginal surgery and prolapse repair with mesh, with a median of 20 to 25 procedures performed a year. They had already participated in a surgical training course, but only few times using animals. Global appreciation of the workshop was good (Table 1). The lifelike qualities of the ewe model regarding surgical procedures was also evaluated by the participants. The following items received the highest grades (grades between 4 and 4.5 out of 5 points): vaginal and bladder dissection, mesh fixation, use of a Capio® suture-capturing device, the ewe’s vaginal properties [laxity, accessibility, and length] received between 4 and 5). Identification of the ischial spine, identification of the sacrospinous ligament and pelvic prolapse items received lower grades (grades between 3.4 and 3.5 out of 5 points). Regarding the comparison between the ewe model and the human cadaver model, the ewe model received significantly better scores for all items evaluated except for Bidentification of ischial spine and sacrospinous ligament^ (Table 2). Fixation and use of Capio® devices were judged to be similar in ewes and human cadavers. Regarding educational purposes, all the participants and supervisors found the ewe to be a better model than human cadavers for training in vaginal surgery with meshes (Table 3). Two vaginal hysterectomies were performed. Operating times were 30 and 35 min respectively. All surgical steps that were described for humans were followed easily while being performed on ewes. A sacrospinous ligament fixation (Richter
Int Urogynecol J Table 1 Characteristics of participants and supervisors
Participants (n = 29) Age (years), mean Specialization Experience in vaginal surgery (years), median class interval Experience in pelvic prolapse surgery (years), median class interval Experience in prolapse surgery with mesh (years), median class interval Vaginal mesh used to repair pelvic prolapse, median class interval per year Assisted at a workshop concerning pelvic prolapse surgery using mesh
Satisfaction of the workshop (1 low to 5 excellent), mean Expectations completed regarding surgical training? Improvement of your surgical skills in pelvic prolapse surgery using mesh? (1 low to 5 excellent)
surgery) was also performed. Dissection was the same, but the ligament aspect was different from that in humans. Finally, obstetric anal sphincter injury was mimicking by cutting with a scalpel from the vagina to the rectum. Repair was performed using an overlap repair technique and was strictly identical with humans. The exact cost of the whole training could not be exactly assessed, as the supervisors received an overall remuneration for their academic work in our center and not a grant for this specific training. The cost of the six human cadavers was
Supervisors (n = 4)
46
44
10 urologists
3 gynecologists
19 gynecologists 10–15
1 urologist 15–20
10–15
15–20
10–15
15–20
25–50
50–75
75% 70% on patients
100% 100% on patients
56% on human cadavers
100% on human cadavers
25% on animals 4.7
25% on animals 4.7
95%
100%
4
4.7
$6,000 ($1,000 per cadaver). The cost of the 15 ewes is $7,500 ($500 per ewe under general anesthesia). Meshes and consumables were supplied by the industry.
Discussion As has been suggested by some authors [4], the ewe is a good model for testing the properties of vaginal mesh. The results of
Table 2 Evaluation of the cadaver and ewe models regarding surgical dissection
Participants (n = 29) Ewes
Colpotomy Vaginal dissection Bladder dissection Identification of the fascia Identification of the ischial spine Identification of the sacrospinous ligament Use of Capio® suture capturing device Fixation of the mesh Vaginal suturing Vaginal accessibility Vaginal length Vaginal laxity Pelvic prolapse
4.4 4.4 4.2 4 3.4 3.4 4.1 4.2 4.5 4.2 4.1 4.3 3.5
Human cadavers 3.4 3.1 3.2 3.2 4.4 4.3 4.2 4.1 3.4 3.5 3.5 2.3 2.4
Supervisors (n = 4) p value
Ewes
<0.001 <0.001 <0.001 0.001 <0.001 <0.001 0.9 0.75 <0.001 <0.001 <0.001 <0.001 <0.001
5 4.7 4.3 4.3 4.3 3.3 4 5 5 4.3 4.7 4.7 4
Human cadavers 2.3 2.3 2.3 2.3 4.7 4.7 4.3 3.3 4 2 2.6 1.3 1.3
Int Urogynecol J Table 3 Pedagogical benefits of the ewe and cadaver models
Participants (n = 29) Ewes
Human cadavers
Supervisors (n = 4) p
Ewes
Human cadavers
Training in vaginal surgery
4.3
3.7
<0.001
5
2.6
Learning surgical repair of prolapse Learning surgical repair of prolapse using mesh
4.1 4
3.7 4
0.16 0.9
4 5
2.6 3
this series indicate that ewes are a useful animal model for teaching vaginal surgery. Questionnaire results showed the superiority of ewes over human cadavers for most of the items evaluated. Indeed, most of the participants were confirmed surgeons and evaluated the model as an appropriate model. Nonetheless, some points should be discussed. Couri et al. reviewed the animal models of female pelvic organ prolapse [4]. We identified the pro and cons of each model (ewes, cows, and monkeys) and we selected the ewe as the more appropriate for teaching vaginal surgery. This choice is justified by several reasons. Mansoor et al. highlighted the potential benefits of performing vaginal prolapse surgery on ewe cadavers [6]. The main advantage of the ewe lies in the similarities between the human and the sheep reproductive anatomy. The dimensions of the ewe and the human vagina are similar in both diameter and length [7, 8]. The pelvic architecture of the ewe also relies on three levels of support, similar to those detailed by DeLancey in women [9, 10]. Furthermore, the ewe has been well documented to acquire spontaneous prolapse [11, 12]. Similar to humans, sheep of all ages can develop prolapse, but the incidence is highest in mature multiparous sheep and the risk increases with each successive pregnancy [11]. Similar to humans, the bladder is often the organ contained within the prolapse. Scott and Gessert found that the uterine horns were present in the 16.7% cases of ewe vaginal prolapse, the bladder alone in 41.7%, and both the bladder and the uterus in 25% [13]. Urethral constriction or kinking was observed in vaginal prolapse involving the bladder, as is often seen in humans, with prolapse and stress urinary incontinence [13, 14]. These results suggest a high similarity between the presentation of prolapse in humans and ewes [15]. The pathophysiology of prolapse in sheep also appears to be similar to that of humans [16]. The main limitation of this animal model is a slight difference between the ewe’s pelvis and the female human one regarding the spine and sacrospinous ligament. Ewes do not exactly have a spine and a sacrospinous ligament, which explains why participants found it harder to identify it. However, these anatomical elements are replaced by similar structures, which were studied by Basset [17]. There is a sharp-edged convex crest, but no discrete ischial spine as in a woman; it is therefore more
appropriate to name this the supracotyloid ridge. The sheetlike sacrosciatic ligament that forming most of the lateral pelvic walls has been considered to be equivalent to a combination of the human sacrospinous and sacrotuberous ligaments. It seems that the sacrosciatic ligament and the prepubic tendon in such an extensive form may be peculiar to ungulates, as they are not thus described for other mammals. Concerning hysterectomy, all the surgical steps are precisely the same. However, it may be noticed that some anatomical elements are quite different. The cervix is physiologically more elongated, but not so much that it could be seen in some patients, especially in women with prolapse. The uterus delivery could be more difficult than for humans. The uterus is didelphic, but does not disturb surgery. The uterus, Fallopian tubes, and ovaries are of the same proportions. Operating times were similar in humans and ewes. As the surgical technique is exactly the same, the ewe is also an appropriate model for managing surgical complications (bladder injury, bleeding). If a limit can be identified, it is that ewes do not develop myomas. Nevertheless, the morcellation technique could be performed. We identified the ewe as an appropriate model for the simulation of nearly all vaginal surgery performed in humans. From our point of view, this was a great success. We will now be able to propose to our residents an appropriate tool for learning and training in vaginal surgery. The ewe may also be an appropriate model for learning autologous prolapse and stress urinary continence surgery.
Conclusion This study shows that ewes, according to the experienced surgeon, is an appropriate model for the teaching and training of vaginal surgery. Better information on the particularities of the ewe’s anatomy will be necessary, particularly for vaginal surgery using mesh. The most interesting aspect of this model is that a range of surgical acts, from basic to advanced, could be performed. Nonetheless, human cadavers should not be banned, as human anatomy is specific, particularly the ischial spine. Our aim is now to develop several training courses
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based on the ewe model dedicated to residents, fellows, and postgraduate surgeons.
7.
8. Compliance with ethical standards Conflicts of interest None.
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