What is the pathophysiology of stress urinary incontinence?

Updated: Mar 19, 2019
  • Author: Sandip P Vasavada, MD; Chief Editor: Edward David Kim, MD, FACS  more...
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Answer

During episodes of stress incontinence, an increase in intra-abdominal pressure (eg, from laughing, sneezing, coughing, climbing stairs) raises pressure within the bladder to the point where it exceeds the urethra’s resistance to urinary flow. [2, 3] Leakage ceases when bladder pressure again falls below urethral pressure.

The major cause of stress incontinence is urethral hypermobility due to impaired support from pelvic floor. A less common cause is an intrinsic sphincter deficiency, usually secondary to pelvic surgeries. In either case, urethral sphincter function is impaired, resulting in urine loss at lower than usual abdominal pressures.

In women with stress urinary incontinence, either or both mechanisms may be present, although some authors hold that stress incontinence does not develop in patients with poor pelvic support unless intrinsic sphincter deficiency is also present. Intrinsic sphincter deficiency, resulting from loss of function of both the internal and the external sphincter mechanism, is the only cause of stress incontinence in males.


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