Stress incontinence is an involuntary loss of control of urine that occurs at the same time abdominal pressure is increased as in coughing or sneezing. It develops when the muscles of the pelvic floor have become weak.

People with stress incontinence lose urine involuntarily while doing certain physical activities that put pressure on the abdomen (lower part of the body between the ribs and hips). These include:

• Coughing, laughing or sneezing

• Lifting

• Walking or performing other forms of exercise

• Moving to get up from a chair or out of bed

It is often necessary to use the bathroom often to avoid accidental urination.

It is believed that stress incontinence occurs when abdominal pressure upon the bladder is not balanced by equal pressure upon the urethra. This occurs when the bladder neck and urethra move down and bulge (herniate) through weakened structures within the pelvis. Herniation causes the angle of the urethra to change, which can cause the urethra to remain open. If the urethra is not pressed shut, urine can leak out.

Many urologists classify stress incontinence by a three-category system:

• Type I is stress incontinence in which the bladder neck and urethra are open and slightly hypermobile (too moveable), and the urethra descends (moves down) less than 2 cm during stress (that is, the angle of the urethra is nearly unchanged). Type I patients also have little or no sign of cystocele.

   

• Type II refers to stress incontinence in which the bladder neck and urethra are closed and very hypermobile, and the urethra descends more than 2 cm during stress that is, the angle of the urethra is increased. Type II patients also may have cystocele; if the cystocele is inside the vagina, the classification is Type IIA; if the cystocele is outside the vagina, the classification is Type IIB.

   

• Type III, or intrinsic sphincter deficiency, refers to severe stress incontinence in which urethral position and support are not factors, but the urethral sphincter is very weak. Type III patients often have undergone a previous, failed surgical procedure.