Animal Models of Female Stress Urinary Incontinence

Purpose

Urinary incontinence affects 40% of women in the United States and stress urinary incontinence accounts for a large portion of affected patients. As defined by the International Continence Society, stress urinary incontinence is the involuntary leakage of urine upon effort, exertion, sneezing or coughing. Since the ultimate success of long-term management for any condition is based on an understanding of its pathophysiology, and because the pathophysiology of stress urinary incontinence is incompletely defined, animal models have recently been developed to better understand stress urinary incontinence and develop novel treatment alternatives.

Materials and Methods

Several animal models for urethral dysfunction have emerged in the last few years, including those based on pathophysiological theories of urethral sphincter dysfunction that were designed to simulate maternal birth trauma. Other models have focused on the creation of a durable model of dysfunction for investigating novel treatments.

Results

Since animals cannot express intent, these animal models have focused on measuring decreased urethral resistance. The most widely used methods are the sneeze test, the tilt table technique and the leak point pressure test. Newer techniques include abdominal leak point pressure, urethral pressure measurement and retrograde urethral perfusion pressure. In addition to the advantages and disadvantages of each technique, all methods measure the composite contribution to urethral resistance from smooth and striated muscle, urethral closure and connective tissue, although none measures intent.

Conclusions

We critically reviewed the different models of stress urinary incontinence and urethral dysfunction as well as the different methods of measuring urethral resistance.

Key Words: urethra, urinary incontinence, stress, female, urodynamics, models, animal

Abbreviations and Acronyms: bFGF, basic fibroblast growth factor, EMG, electromyography, EUS, external urethral sphincter, LPP, leak point pressure, MDSC, muscle derived stem cell, OVX, ovariectomy, PLGA-ms, poly-lactic-glycolic acid microspheres, PNC, pudendal nerve crush, RUPP, retrograde urethral pressure profile, SUI, stress urinary incontinence, VD, vaginal distention