**Animal Models of Double Incontinence: "Fecal and Urinary" "Fecal and Urinary"**

**Animal Models of Double Incontinence:** 

DOI: 10.5772/intechopen.69962

Raheela Mohsin Rizvi and Sanam Imtiaz

Raheela Mohsin Rizvi and Sanam Imtiaz Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.69962

#### **Abstract**

Throughout the world, animal models are being used as simulators of human anatomy and pathophysiology with most of the investigations and treatments first tested on them. Double incontinence (DI) includes both urinary and anal incontinence. This chapter is focused on the use of animals as models to understand pathogenesis, diagnosis and man‐ agement of double incontinence (DI). DI is a complex disease with variant prevalence around the world which has a severe impact on quality of life (Qol). Many studies are designed to employ rodent and rabbit models to understand the pathogenesis of urinary and fecal incontinence. Urodynamic studies including leak point pressure (LPP) and ure‐ thral pressure profilometry (UPP) are used in establishing diagnosis of stress urinary incontinence. Rats have also been used to study fecal incontinence using neurophysi‐ ological and sacral nerve stimulation tests. The surgical treatment of double incontinence involves use of mesh, which was initially tested on animals. Animal models have also been used to train surgeons for perineal tear repair surgery. We conclude that the use of animal models provides best approach to learn these specialized surgical skills for medi‐ cal practitioners and researchers.

**Keywords:** animal model, double incontinence, stress incontinence, fecal incontinence, human

### **1. Introduction**

The prevalence of female urinary incontinence (UI) in Europe ranges from 14.1 to 68.8% and increases with age [1]. Specifically, stress urinary incontinence (SUI) is highest among all types of UI and is estimated at 23.7% [2]. The prevalence of fecal incontinence (FI) ranges from 2.2 to 50% in women with urinary incontinence or pelvic organ prolapse [3]. FI and UI are pelvic floor disorders (PFD) which lead to social embarrassment and have poor impact

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

on quality of life. Over \$12 billion are spent annually for management of SUI in women [4]. The average annual total cost for fecal incontinence is estimated at \$4110 per person [5]. Stress urinary incontinence (SUI) may be defined as involuntary loss of urine on effort or physical exertion (e.g., sporting activities), or on sneezing or coughing. Urgency urinary incontinence (UUI) relates to involuntary loss of urine associated with a desire to void, while anorectal incontinence (AI) is a complaint of involuntary loss of feces or flatus.

[10]. The role of urodynamic studies (UDS) is important in identifying types of SUI. Types of SUI can be determined with valsalva leak point pressure (VLPP) and urethral pressure profilometry (UPP). According to Blaivis, SUI types 1 and 2 are related to urethral hyper mobility with VLPP > 90 cm of water for type 1 and between 60 and 90 cm of water for type 2, respectively. Blaivis type 3 SUI is with VLPP < 60 cm water, also known as intrinsic sphincter deficiency (ISD). In addition, a urethral pressure profile (UPP which is urethral pressure– detrusor pressure) < 20 cm water is also seen in the cases of ISD [12]. Animal models that simulate SUI provide an assessment of the mechanism of risk factors, including childbirth injuries, preclinical testing of new treatments and therapies for SUI. Since animals cannot express intent, the use of these animal models has been focused on measuring decreased

Animal Models of Double Incontinence: "Fecal and Urinary"

http://dx.doi.org/10.5772/intechopen.69962

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SUI is clinically assessed on humans as observation of involuntary leakage from the urethra with effort or physical exertion, or on sneezing or coughing [10]. Based on the urinary leak with a rise in abdominal pressure, sneeze test can be performed in female rat under anesthe‐ sia. A whisker cut from anesthetized rat was used to tickle its nose. Even under anesthesia the rat responded with a small sneeze, which transiently increased abdominal pressure. Karl et al. performed cystometry with methylene blue dye in bladder to detect urinary leak. The animal was diagnosed as incontinent if they leaked during the sneeze test and continent if no leak on

The human bladder functions by storage and voiding of urine. Voiding is accompanied by an increase in detrusor pressure and a decrease in urethral pressure. In leak point pressure (LPP) testing [15], rats were anesthetized and a transperitoneal catheter implanted in the blad‐ der dome was tunneled subcutaneously from the back of the bladder neck to an exit via the skin. The catheter was capped and the skin incision closed in two layers. The bladder catheter was connected to both a syringe pump and a pressure transducer. The bladder when filled with room‐temperature saline through the catheter, the bladder pressure was recorded via a microtip transducer urethral catheter. Pressure and force transducer signals were amplified and recorded on a chart recorder. All bladder pressures were referenced to air pressure at the level of the bladder very similar to LPP assessment in humans with use of external trans‐ ducers. The three commonly used mechanisms are manual pressure/Crede's LPP, electrical

To perform manual LPP testing in rats, they put supine on table and a passive/manual abdominal pressure is applied and increased gradually, thus increasing the vesical pressure until leakage is observed at the urethral meatus. The peak bladder pressure was taken as the LPP. After leak, the external pressure is rapidly removed and bladder pressure quickly

urethral resistance [13].

sneezing was observed [13, 14].

stimulation LPP and table tilt LPP [16–18].

*2.2.1. Manual LPP testing*

returns to baseline [17].

**2.1. Sneeze testing**

**2.2. LPP testing**

The ultimate success of long‐term management for double incontinence (DI) is based on an understanding of disease pathophysiology. Little is known about the degree to which UI and FI share risk factors. Animal models have been used to understand pathogenesis of these conditions in humans and for developing novel treatment alternatives. Even though many animal models have been developed to understand pathogenesis, yet many of etiological fac‐ tors are not explained. Many animal models are used as simulators for teaching surgical skills but long‐term studies have not shown the desired improvement in surgical outcome [6]. The surgical procedures in humans were developed through the use and application of animal model as slings and trocar‐driven implants [7] for anti‐incontinence procedures.

Urinary incontinence is relatively easy to understand when compared to fecal incontinence as anal sphincter defects and FI are complicated surgical problems. Research on use of stem cell for treatment of FI was conducted on rabbits by an iatrogenic sphincter defect, created by cutting of anal sphincter. Human umbilical cord matrix (hUCM) and stem cells from rabbit femur and tibia were harvested and transplanted into injured sphincters which later showed an improvement in their function. Bone marrow‐derived stem cells and mesenchymal cells of animals have shown to enhance contractile function of anal sphincter without surgical repair [8]. The limitation of using animals is in their difference with anatomy and size of vis‐ cera, which affects the functional outcome. Human cadavers have been used for a long time for teaching anatomy, but due to ethical issues animals were introduced in medical teach‐ ing. Animal models were found quite effective, but because of major difference in functional anatomy, mannequins were introduced for medical teaching and learning. There are many centers for simulation‐based innovation for medical education (SIME), which probably would give similar results [9].

Most of the studies on new medical and surgical treatment involve the use of animal mod‐ els for preclinical trials. In this chapter, we discussed use of animal models for relevant research, procedures on pathogenesis and surgical training techniques for DI. We have used standardized terminology for definitions as described by the International Continence Society (ICS) and International Urogynecological Association (IUGA) joint report on ter‐ minology [10, 11].
