Incontinence is classified by both causes and symptoms. The two most common types are called urge incontinence and stress incontinence, which can present separately or in combination:
- Urge incontinence, also called “bladder instability” or “overactive bladder,” is primarily bladder "misbehavior" and is characterized by spontaneous and uncontrolled urine leakage often accompanied by the overwhelming sensation of needing to void. Many people with this condition also have difficulty with bowel control and report frequent bowel movements or difficulties with constipation. The causes of urge incontinence are not clearly known, but is likely related to changes in the nerves controlling the bladder. Learned voiding behaviors, aging, hormonal changes, prior childbirth, previous surgery, dietary habits and other factors appear to influence this condition.
- Stress incontinence is primarily due to weakness of the valve mechanism (sphincter) in the bladder outlet and urethra. This may be due to intrinsic changes in the urethra, or loss of support and strength of the bladder neck and adjacent structures. It is also associated with post surgical or radiation changes in men following treatment for prostate cancer. With physical exertion or activity that increases abdominal pressure, urine is forced through the deficient valve.
Another type of leakage is termed overflow incontinence. This results from failure of the bladder to empty either from weakness, nerve injury or blockage to flow. With an overfull bladder, exertion or abdominal pressure can cause urine to spill out.
Other conditions such as urinary tract fistulae (holes between the urinary tract and other structures), stroke, spinal cord injury and other neurologic diseases can also cause incontinence and voiding problems.