What is Stress Incontinence?
If urine leaks out when you jump, cough, or laugh, you may have stress incontinence. Any physical exertion that increases abdominal pressure also puts pressure on the bladder. The word “stress” actually refers to the physical strain associated with leakage. Although it can be emotionally distressing, the condition has nothing to do with emotion. Often only a small amount of urine leaks out. In more severe cases, the pressure of a full bladder overcomes the body’s ability to hold in urine. The leakage occurs even though the bladder muscles are not contracting and you don’t feel the urge to urinate.
Stress incontinence occurs when the urethral sphincter, the pelvic floor muscles, or both these structures have been weakened or damaged and cannot dependably hold in urine. Stress incontinence is divided into two subtypes. In urethral hypermobility, the bladder and urethra shift downward when abdominal pressure rises, and there is no hammock-like support for the urethra to be compressed against to keep it closed. In intrinsic sphincter deficiency, problems in the urinary sphincter interfere with full closure or allow the sphincter to pop open under pressure. Many experts believe that women who have delivered vaginally are most likely to develop stress incontinence because giving birth has stretched and possibly damaged the pelvic floor muscles and nerves (see “The childbirth connection,” below). Generally, the larger the baby, the longer the labor, the older the mother, and the greater the number of births, the more likely that incontinence will result.
Age is likewise a factor in stress incontinence. As a woman gets older, the muscles in her pelvic floor and urethra weaken, and it takes less pressure for the urethra to open and allow leakage. Estrogen can also play some role, although it is not clear how much. Many women do not experience symptoms until after menopause.
In men, the most frequent cause of stress incontinence is urinary sphincter damage sustained through prostate surgery or a pelvic fracture.
Lung conditions that cause frequent coughing, such as emphysema and cystic fibrosis, can also contribute to stress incontinence in both men and women.
The childbirth connection
It’s a little-known fact that many childbirth classes fail to adequately cover: an estimated 40% of women who give birth vaginally go on to develop one or more of the problems collectively known as pelvic floor disorders. These include stress incontinence, overactive bladder, uterine prolapse (in which the uterus drops out of its normal position), cystocele (in which the bladder bulges into the vagina), rectocele (in which the rectum bulges into the vagina), and fecal incontinence. These disorders often grow worse over time, requiring surgical repair in at least 11% of women over all.
Vaginal delivery can lead to pelvic floor damage as the baby stretches the pelvic floor muscles and other tissues on its way through the birth canal, sometimes causing tearing or other damage. Research results show that a number of factors raise the risk of damage for women who deliver vaginally, including these:
What are the solutions? Delivery by cesarean section protects against severe incontinence, but some women do develop incontinence even if they have only had cesarean sections. As the rate of cesarean section continues to rise (about 31% of babies were delivered by cesarean section in 2006), many women and health professionals are concerned that too many unwarranted cesarean deliveries are performed. Research to help determine when a cesarean is the best choice is ongoing.
Women with some of the above risk factors should bear them in mind when considering their birth options. Researchers who published a study in the journal Obstetrics and Gynecology in 2006 suggested that health professionals inform their patients that cesarean delivery would reduce the risk of pelvic floor injury by 85%. This study of 4,458 women found that stress incontinence was 86% more likely in women who delivered vaginally compared with those who had cesarean section. Anal incontinence was 72% more common, and overactive bladder was 53% more common. But even cesarean delivery can, in rare cases, cause incontinence, and because cesarean delivery comes with its own set of risks, each woman should discuss her situation thoroughly with her obstetrician while making plans for childbirth.
The use of episiotomy during childbirth has declined steadily, but millions of women have had episiotomy in the past. It was previously believed that episiotomy helped prevent tearing of the vagina and damage to the pelvic floor. However, evidence has failed to confirm any benefit. And episiotomy may cause more damage than it prevents. For example, a 2006 study in Obstetrics and Gynecology found that women who had episiotomy were the most likely to experience tears in the anal sphincter. After sphincter tear and repair, about half of women experience fecal or gas incontinence. For many women, the symptoms improve or disappear within a few months, but others sustain persistent or worsening problems, or find that symptoms reappear after subsequent deliveries. Besides episiotomy, other major factors contributing to sphincter tears were heavier babies, a prolonged second stage of labor, and forceps delivery. Vacuum delivery did not lead to sphincter tear. Gentle delivery techniques and slow, gradual induction (when induction is necessary) would go a long way toward sparing women incontinence resulting from childbirth.
Pregnant women can talk with their health care providers in advance about their specific risk factors for pelvic damage and consider their childbirth choices in the context of these risk factors. Women who already have symptoms of pelvic floor damage can learn more about treatment options in this report.