What's really behind childhood voiding issues?
By Joseph Borer, MD
How do children learn to take control of their bladder function?
Bladder function and reflexes develop gradually. In the first year or two, this helps the bladder function in a reflex kind of way: as the bladder fills to a certain point, it will automatically contract and empty. At a certain age, a child will develop the ability to control the bladder by controlling the sphincter muscle, just outside the bladder around the urethra. Contraction will hold urine in the bladder while relaxation lets the bladder out. It's a gradual process from an unconscious function of the bladder to a volitional act as the sensation of bladder fullness arises, beginning around age 2 for some children and a little older in others.
Can problems in this development be a result of congenital anomalies or trauma?
Yes. Spina bifida, for example, damages the nerves running from the spinal cord to the bladder or sphincter muscle. This impacts the bladder, which then functions abnormally: it may not hold as much urine as it should, it may not contract the way it should in order to empty, or there may be a discoordination of the bladder and sphincter muscle. Similar problems in the urinary tract can develop from a traumatic injury to the spinal cord. In these cases, sensory and motor activity will not function correctly, and we'll find abnormalities in bladder function and sphincter function.
There are also abnormalities that can be learned. If a child becomes aware of a full bladder and decides not to urinate, or void, by contracting the external urethra sphincter muscle, he or she can acquire an abnormality in the system. This is similar in effect to the discoordination of the bladder and sphincter muscle seen in spina bifida or a trauma patient.
What signs should pediatricians look for to indicate an acquired abnormality?
Perhaps the most common sign is squatting behavior, which is specifically undertaken to inhibit the urge to urinate. The child senses this need, but willingly chooses to ignore it, if possible, in order to continue their current activity such as playing, reading or watching television. This behavior will stop the urge, which is itself a result of a bladder contraction beginning, and cause that bladder contraction to cease. It becomes a cycle that over time can damage the bladder and result in other signs such as frequency (need to urinate often), urgency (sensation of immediate need to urinate) and urgency incontinence (leaking of urine when child cannot get to the bathroom in time). Constipation may also accompany the acquired voiding abnormalities.
What separates behavioral issues with voiding and those that arise from physiologic changes?
The signs themselves, such as frequency, urgency and urgency incontinence, cannot necessarily help parents or physicians distinguish between behavioral or physiological causes, as they are the result of both of these causes. However, a careful history of events coming before the onset of these signs is most helpful in determining the cause. Without evidence of squatting or other voiding postponement behavior, the physician should evaluate carefully for a possible physiologic cause.
How often do children who have taken control of their voiding habits revert to uncontrolled voiding?
Why does this happen?
We see many children who have learned to control their bladder habits and then go on to abuse this ability with willful postponement of the urge to void,
ignoring the body's signal that it is time to empty the bladder. This cycle stretches the bladder and allows it to hold more urine for a longer time, but if the cycle is carried on for a long period of time (months to years), the bladder and sometimes the kidneys can be permanently damaged. One reason this may occur is the child's perceived benefit of the postponement cycle early in the cycle's course.
What kind of behavioral regimen is involved in treating children with an acquired abnormality?
The most important behavioral regimen focuses on developing a timed voiding schedule. The child is asked to attempt to void upon waking in the morning (even if he/she wet the bed), and then attempting to void every two to three hours thereafter. A watch with an alarm can be helpful in reminding the child and help incorporate the timed voiding schedule into their daily routine. For children who cannot hold the urine for a minimum of two hours, medication that relaxes the bladder muscle may be temporarily necessary in order to help the bladder regain the ability to function normally. All voiding postponement behavior must be discouraged. Encouraging complete relaxation at the time of voiding is also important. If constipation is also present it should be aggressively treated.