Our disclosures are as shown. Different sized animals have been used with success in urogynecologic research. Small animal models have included mice, rats, and rabbits. A major drawback to these models is that surgery on small animals requires specialized instruments. Additionally, the size of the surgical intervention may not be clinically relevant. Large animal models have been used with success. These include macaques, which are bipedal, thus a good model for psychokalpapexy mesh tensioning. Additionally, sheep and emu have been used. These animals are quite expensive and come with their own handling challenges. Our institution has extensive experience with the swine surgical model, but we, nor what is published in the literature, has fully leveraged a swine gynecologic surgical model. Two studies have evaluated using swine as urethral models and thoroughly described urethral growth anatomy and histology. Another study examined pig anatomy, including the vagina and uterus sacral ligaments. Their histology and dissections confirmed similarity to humans. Physiologic testing has been performed on the explanted uterus sacral ligaments. Aside from stress urinary incontinence, there is no existing porcine gynecologic surgery model. Given sparse literature regarding swine surgical models, our goals were twofold. The first was to explore the feasibility of using swine as a surgical model in urogynecology. The second was to perform dissections in female swine to compare porcine and human anatomy, thus providing essential information for development of future protocols should investigators choose a porcine surgical model. We achieved our goals by performing dissections on five porcine cadavers, as well as operating on, recovering, and sacrificing six swine for postmortem assessment in the form of histologic, immunohistochemical, and electron microscopy evaluation. We will now discuss some pertinent porcine anatomy as it relates to urogynecologic procedures. The sacrum and retroperitoneal structures in a postmortem dissection are shown here. Here we see the porcine sacral pomentary, male sacral artery, ureter, and iliac bifurcation. These all have anatomy and spatial relationships analogous to humans. Here you see the genitourinary system. The arrows show the tubular uterus. On the left is a close-up of the uterus. Note that it is long and tubular to allow for multiple gestations. On the right, you see the ovary. Here is the urinary bladder, which has structure and capacity similar to humans. The bladder has been bivalved here, and one of the ureter orifices identified. Depicted here is an explanted genitourinary tract. Note the major difference in porcine gene anatomy, which is shown here. The bladder and urethra spill into the posterior vaginal canal. The urethral meatus is an internal rather than external structure. Vaginal microanatomy is similar to humans. Here we show images of porcine vaginal epithelium on the left and human on the right. Note that the stratified squamous epithelium and underlying connective tissues are similar. This was confirmed by histology and transmission electron microscopy in our cohort of pigs. The POPQ is a useful clinical tool to standardize prolapse reporting. A prolapse surgical model would ideally have comparable anatomy and measurements to humans. Here we show the pig introitus. The vaginal mucosa is similar, though there is a median raft conglomeration of connective tissue that runs parallel to the ventral vagina. The rectum and tail are dorsal to the vagina. The perineal body is approximately 3 to 4 centimeters. Total vaginal length is approximately 14 centimeters. Note that obtaining a GH is not feasible given the urethral meatus is internal. We would suggest four applications of the porcine surgical model, the first being sacrocolopexy, as well as vaginal surgery, isolated ureteral and urethral injury and repairs, and anal sphincter and or fecal incontinence. Our institution has specifically used swine as a model for intrinsic sphincter deficiency, fourth-degree OB lacerations, and vaginal mesh surgeries. We will focus on the latter for the remainder of this presentation. We will now discuss preparations for and describe techniques for performing vaginal mesh surgeries in swine. In planning your experiments and deciding on pig size, we recommend taking the type of surgery you plan to perform into consideration. For vaginal and urethral surgery, we would recommend 80-kilogram pigs, whereas for anal and perineal surgery, we would recommend 60-kilogram animals. In addition, it is important to consider institutional infrastructure. A team of experienced veterinarians and veterinary technicians is key to ensuring study animals are properly housed, fed, and cared for in the perioperative period. It is preferable to socially house pigs in raised cages. We will now present some considerations for positioning and surgical prep. Given pigs' quadrupedal nature and the need for surgical access to the vagina, anus, and urethra, we would recommend positioning the pig into the prone jackknife position on the edge of the OR table. We place rolled blankets underneath the pigs' hips to provide padding and elevate the GU organs for better exposure. Surgical preparation can be performed similar to humans, taking care to thoroughly cleanse the anus or evacuate the rectum, given it lies above the vagina in this position. For surgical preparation, we use Betadine. We prep inside the vagina in the usual fashion. Finally, a keyhole drape is recommended. The tail can be retracted from the surgical field by deflecting it with a drape and securing the drape with a towel clamp. We will now describe a vaginal mesh surgery with discussion of recommended instruments and equipment. Note that in the depicted surgery, we purposely created a mesh exposure model. We would recommend one of several types of small retractors to establish visualization, a nasal speculum, Wheatlander, or Army-Navy retractor. We first mark the area for which we would like to excise the vaginal epithelium. Pure cut current is then used to outline this area. Epithelial dissection can be performed in a similar fashion to that in humans. Though there is a ventral median raft, which makes dissection in that area a bit more challenging. Dissection may be performed with electrocautery or sharp dissection. Following this, we then place 2-O-proline sutures. We thread these sutures through the mesh and secure the mesh with knots. This completes the mesh implantation surgery. Here is the final product. So why use a porcine surgical model? This model has proven anatomical similarity to humans. Additionally, their vaginal caliber and depth allow for multiple endpoints or implants to be placed per animal. This may reduce the number of sacrifices necessary to achieve a meaningful result. The porcine model has a lower cost relative to macaques and other large animals. Finally, swine are easy to handle and train behaviorally. There are inherent limitations to the porcine surgical model. Remember that we had to position the pigs into the jackknife position, which makes their anatomy somewhat upside down. The uterine anatomy is also different. Finally, the urethra empties into the vagina, which makes this a non-ideal model for slings. In performing gynecologic surgeries on and cadaveric dissections of female pigs, we have gleaned a tremendous amount of information regarding their use as a gynecologic surgical model. In the planning stages, set yourself up for success. Make sure you have the right instruments, infrastructure, and appropriate veterinary assistance. Given some differences in anatomy, tools, and approaches to surgical exposure, we recommend cadaver dissections prior to study initiation. Also, start simple. The anus and perineum are most accessible, whereas the urethra is the most challenging to access. Don't forget about usual postoperative care. Postoperatively, they will also need a bowel regimen and adequate pain control. We recommend a long-acting antibiotic following surgery. Finally, plan your endpoints and outcomes early. Immunohistochemistry and fluorescence stains for pigs are less readily available. Use of human stains is possible, but this may require a tedious validation process. And last but not least, find a ritual to honor and thank your animals for the scientific progress they have made possible.

animal models

urogynecologic research

swine surgical model

anatomical similarities

sacrum