Bladder capacity can be determined by age, gender and general level of health. People who have incontinence can experience leakage of fluid before the bladder fills to capacity as a result of poor sphincter control or other issues. If a patient develops reduced bladder capacity, a urologist can evaluate the patient to learn more about the situation and determine whether any treatment measures are available. Sometimes the reduction is permanent and cannot be reversed. In other cases, treatment might allow the bladder to return to its normal capacity.
Very young children tend to have low bladder capacity because their bodies are still growing, and although the bladder can expand and contract as needed, a full-sized adult bladder would not fit in the body of a child. At the other end of the spectrum, older adults also tend to have a lower capacity because their bladders are less elastic. Older men also are more likely to experience prostate enlargement, which can cut down on the amount of room available for the bladder to expand.
Women tend to have smaller bladders than men because their pelvic regions are filled with internal genitalia, so there is less space. During pregnancy, the available space decreases even more as the developing fetus swells in the pelvis and pushes the bladder out of the way. Pregnant women experience a frequent urge to urinate because as the bladder reaches capacity, nerve signals alert the body to the need to void the bladder before the urinary sphincter fails.
Underlying disease also can affect bladder capacity. Some conditions might reduce the elasticity of the bladder and make it more difficult to expand. Interstitial cystitis is a common culprit. This disease causes chronic inflammation of the bladder, which can lead to scarring and less capacity. In addition, patients who have a condition called neurogenic bladder might experience reduced bladder capacity because pressure rises too quickly in the bladder and forces the urinary sphincter to open.
A urologist can order a series of tests on a patient's urinary bladder if a problem is suspected. These can include a test to determine capacity and control, using contrast materials introduced to the bladder through a catheter. It might be possible to expand a patient's bladder capacity with treatment. In other cases, the patient might need to exercise caution to prevent incontinence. This could include using a catheter to drain the bladder in extreme cases or when a patient cannot urinate independently.