[Paper Review] A Clinical and Finite Elements Study of Stress Urinary Incontinence in Women Using Fluid-Structure Interactions

Mojtaba Barzegari, Bahman Vahidi+1 more|arXiv (Cornell University)|Aug 4, 2017

Pelvic floor disorders treatments20 references3 citations

TL;DR

This study develops a fluid-structure interaction (FSI) finite element model to simulate stress urinary incontinence (SUI) in women under abdominal pressure, using linear material properties and pressure boundary conditions. The model shows strong agreement with clinical data, particularly in predicting central bladder pressure, demonstrating that simplified computational models can effectively replicate physiological responses in the lower urinary tract.

ABSTRACT

Stress Urinary Incontinence (SUI) or urine leakage from urethra occurs due to an increase in abdominal pressure resulting from stress like a cough or jumping height. SUI is more frequent among post-menopausal women. In the absence of bladder contraction, vesical pressure exceeds from urethral pressure leading to urine leakage. Despite a large number of patients diagnosed with this problem, few studies have investigated its function and mechanics. The main goal of this study is to model bladder and urethra computationally under an external pressure like sneezing. Finite Element Method and Fluid-Structure Interactions are utilized for simulation. Linear mechanical properties assigned to the bladder and urethra and pressure boundary conditions are indispensable in this model. The results show good accordance between the clinical data and predicted values of the computational models, such as the pressure at the center of the bladder. This indicates that numerical methods and simplified physics of biological systems like inferior urinary tract are helpful to achieve the results similar to clinical results, in order to investigate pathological conditions.

Motivation & Objective

• To investigate the biomechanical mechanisms of stress urinary incontinence (SUI) in women using computational modeling.
• To simulate bladder and urethra behavior under external abdominal pressure, such as during coughing or sneezing.
• To evaluate the accuracy of finite element models incorporating fluid-structure interactions against clinical measurements.
• To assess the feasibility of using simplified linear material properties and pressure boundary conditions in modeling SUI pathology.

Proposed method

• Finite Element Method (FEM) is employed to discretize the bladder and urethra geometry for structural analysis.
• Fluid-structure interaction (FSI) modeling couples the fluid dynamics of urine with the mechanical response of the urethral and bladder tissues.
• Linear elastic material properties are assigned to the bladder and urethra to simplify biological tissue behavior.
• Pressure boundary conditions are applied to simulate abdominal pressure increases during stress events like coughing.
• The computational model predicts internal pressures and deformation patterns under simulated physiological loading.
• Model validation is performed by comparing predicted central bladder pressure with clinical data.

Experimental results

Research questions

• RQ1 How accurately can a finite element model with fluid-structure interaction predict central bladder pressure during abdominal pressure increases?
• RQ2 To what extent do linear material properties and simplified boundary conditions reflect real physiological responses in SUI?
• RQ3 Can computational modeling replicate clinical observations of urine leakage under stress conditions?
• RQ4 What is the correlation between simulated pressure values and actual clinical measurements in SUI patients?

Key findings

• The finite element model successfully predicts central bladder pressure with strong agreement to clinical data.
• The simulated pressure values at the bladder center closely match reported clinical measurements, validating the model's accuracy.
• The use of linear mechanical properties and pressure boundary conditions yields physiologically plausible results.
• Fluid-structure interaction modeling effectively captures the dynamic response of the lower urinary tract under stress.
• The study confirms that simplified computational models can replicate complex urodynamic behaviors in SUI.
• The results support the application of numerical methods in studying pathological conditions of the lower urinary tract.