Changes in the extracellular matrix in periurethral tissue of women with stress urinary incontinence.

Changes in structural support of the urethra and bladder neck have been proposed as important factors in the pathogenesis of stress urinary incontinence (SUI). In this context, we undertook an ultrastructural study on the periurethral connective tissue with an emphasis on incontinent women with normotonic and hypotonic urethras. Small specimens of periurethral connective tissue were obtained by dissection during a tension-free vaginal tape-implantation procedure in 34 stress urinary incontinent postmenopausal women with a normotonic urethra and 9 stress urinary incontinent postmenopausal women with a hypotonic urethra. In the samples taken from stress-incontinent women with a normotonic urethra, intact elastic fibers were closely connected with collagen fibers, smooth muscle cells and fibrocytes. In the samples taken from stress-incontinent women with a hypotonic urethra, we detected irregular fragmented distribution of the elastin within the tissue. We assume that these structural changes lead to functional consequences, such as diminished tissue extensibility and loss of stability surrounding the female urethra. These altered connective tissue properties may affect the mechanism of urethral closure under stress (e.g., coughing) and therefore contribute to the occurrence of SUI with a hypotonic urethra.