Gaining consistent control of bladder and bowel during daytime hours is a significant milestone for a toddler or preschooler. For many children, keeping the bed dry at night is a more elusive goal, one that might not be reached until quite a bit later in life. Children who still wet the bed at night well into their grade-school years too often take an emotional beating and in some cases, a physical beating because of this problem – which is not under their conscious control. One of the greatest problems faced by bed-wetting children is a parent with unrealistic expectations that every child should be completely dry, day and night, by the age of three. To deal with bed-wetting effectively and supportively, it is important to understand some basic realties of nighttime bladder function in children.
Enuresis is the involuntary passage of urine into the bed or clothes at least once or twice per month in a child who is at least five years of age.
A child with primary enuresis has never contained consistently dry through the night for more than six to twelve months. A child with secondary enuresis has achieved consistent nighttime bladder control for six to twelve months and then for some reason lost it.
Only about 1 percent of children with enuresis will be found upon medical examination to have an underlying disease or disorder such as a urinary tract infection, diabetes, significant constipation, a congenital abnormality of the urinary tract, or a disturbance in the central nervous system. When evaluating persistent bed-wetting, a child’s physician will consider these physical possibilities (which usually have other manifestations) and carry out appropriate studies if necessary.
In the other 99 percent of children with enuresis, the problem may involve one or more of the following. (Clinicians are not in complete agreement about the relative importance of each of these factors.)
Delayed maturation. During infancy, the bladder automatically empties six to eight times per day when a certain volume of urine is present. As a child matures, this emptying reflex is inhibited (held in check) by the central nervous system, so that he can hold larger amounts of urine and eventually release it voluntarily. In general, control is achieved earlier by girls than by boys. By the age of three, most children can consistently postpone urinating during waking hours. However, the ability of a child’s central nervous system to inhibit emptying of the bladder during sleep may lag behind daytime control by months or even years. By the age of five, as many as 10 to 15 percent of children are not consistently dry in the morning.
- Small functional bladder capacity. A normal child can usually voluntarily hold urine in an amount of ounces equal to his age in years plus two. (A six-year-old child, for example, should be able to hold about eight ounces of urine.) If a child cannot hold at least the same number of ounces as his age, this decreased capacity may contribute to enuresis.
- Increased formation of urine during the night. Hormone called vasopressin, which is produced by the pituitary gland, reduces urine production by the kidneys. An increased amount of this hormone is normally secreted during the night cutting the rate of urine production in half. Some bed wetters apparently do not secrete more vasopressin during the night and produce more urine than their non-bed-wetting peers. A similar rest may occur, regardless of vasopressin levels, if a child consumes liquids before going to bed.
- Difficulty awakening when the bladder is full. With the general patterns of sleep are similar in both bed-wetting and non-bed-wetting children, many parents observe that their child with enuresis will “sleep through anything” and seems very difficult to awaken during the night.
- A family history of enuresis. Due to many of the factors contributing to bed-wetting having inheriting physiological basis, it should not be surprising that this problem often runs in families. Enuresis seven times more common in children whose fathers were bed wetters and five times more common if the mother had this problem. If both parents were bed wetters, the likelihood that the child will have enuresis is greater than 75 percent compared to a 15 percent chance if neither parent was a bed wetter.
If your child is wetting the bed repeatedly after their sixth birthday, an evaluation by your child’s physicist is a reasonable first step. (Very often this problem can be addressed during a routine checkup.) A careful history and a physical examination will be performed, with any appropriate laboratory studies (such as analysis). A culture of the urine will be taken if there is concern about an infection. In most cases elaborate agnostic tests are not needed. But if the initial assessment raises concerns about the structure or function the urinary tract, your child’s physician will want to evaluate further.
If a child develops secondary enuresis – that is, he is being consistently dry in the morning for more than six months and then begins wetting the bed again, a bladder infection or diabetes might be manifested in this way.