Stress incontinence is the uncontrolled loss of urine when coughing, straining, sneezing, lifting heavy objects, or performing any maneuver that suddenly increases pressure within the abdomen. Stress incontinence is the most common type of incontinence in women. It can be caused by weakness of the urinary sphincter. Sometimes the cause is changes in the urethra resulting from childbirth or pelvic surgery. In postmenopausal women, stress incontinence occurs because a lack of the hormone estrogen contributes to a weakened urethra, thus reducing the resistance to urine flow through this channel.
Overflow incontinence is the uncontrolled leakage of small amounts of urine from a full bladder.
The leakage occurs when the bladder becomes enlarged and insensitive because of chronic retention of urine. Pressure in the bladder increases so much that small amounts of urine dribble out. During a physical examination, a doctor can often feel the full bladder. The person ultimately may be unable to urinate because urine flow is blocked or because the muscles of the bladder wall can no longer contract. In children, blockage of the lower urinary tract may be caused by narrowing of the end of the urethra or of the bladder neck.