Carol D. Berkowitz, MD, FAAP
A 9-year-old boy who is in good general health is evaluated for a history of bed-wetting. He is the product of a normal pregnancy and delivery, and he achieved his developmental milestones at the appropriate time. The boy was toilet trained by the age of 3 years, but he has never been dry at night for more than several days at a time. Bed-wetting occurs at least 3 to 4 times a week even if he is fluid restricted after 6:00 pm. The boy never wets himself during the day, has normal stools, and is an average student. His father had enuresis that resolved by the time he was 12 years old. The boy’s physical examination is entirely normal.
1. What conditions account for the symptoms of enuresis?
2. What is the appropriate evaluation of children with enuresis?
3. What is the relationship between enuresis and emotional stresses or psychosocial disorders?
4. What management plans are available for enuresis?
5. How do physicians decide which management technique is appropriate for which patients?
Enuresis is defined as involuntary or intentional urination in children whose age and development suggest achievement of bladder control. Voiding into the bed or clothing occurs repeatedly (at least twice a week for at least 3 consecutive months). On average, urinary continence is reached earlier in girls than in boys, and the diagnosis of enuresis is reserved for girls older than 5 years and boys older than 6 years. The term diurnal enuresis, wetting that occurs during the day, has been replaced by daytime incontinence. The International Children’s Continence Society promotes a standardization for enuresis-related terminology. It prefers the use of the term incontinence to denote uncontrollable leakage of urine, intermittent or continuous, that occurs after continence should have been achieved. Nocturnal or sleep enuresis refers to involuntary urination or incontinence that occurs during the night. The term primary nocturnal enuresis is used when children have never achieved sustained dryness, and secondary enuresis is used when urinary incontinence recurs after 3 to 6 months of dryness. Monosymptomatic nocturnal enuresis means that nighttime wetting is the only symptom. Children who experience urgency, frequency, dribbling, or other symptoms have polysymptomatic enuresis. Such symptoms may be related to inappropriate muscle contraction, are often associated with constipation, and are termed dysfunctional elimination syndrome or bowel/bladder dysfunction.
Physicians can be particularly helpful by routinely questioning parents about bed-wetting during health supervision visits. Many families are otherwise reluctant to bring up this embarrassing concern because enuresis is viewed as socially unacceptable. It poses particular difficulties if children are invited to sleep away from home, such as at a slumber party. In addition, enuresis may be associated with other behavioral or developmental problems, such as attention-deficit/hyperactivity disorder (ADHD), anxiety, and depression, that warrant inquiring about.
Enuresis affects 5 to 7 million individuals in the United States. It is 1 of the most common conditions of childhood, affecting 10% to 20% of first-grade boys and 8% to 17% of first-grade girls. By age 10 years, 5% to 10% of boys still are enuretic (1% of US Army recruits are enuretic). Seventy-four percent of affected children have nocturnal enuresis, 10% daytime incontinence, and 16% both. Primary enuresis affects the majority (75%–80%) of children with enuresis, and 80% to 85% of these children have monosymptomatic nocturnal enuresis. Although the overall prevalence of secondary enuresis is lower (20%–25%), it increases with age; secondary enuresis makes up 50% of cases of enuresis in children 12 years of age.
Several epidemiological factors have been associated with enuresis, including low socioeconomic status, large family size, single-parent family, low birth weight, short height at 11 to 15 years of age, immature behavior, relatively low IQ, poor speech and coordination, and encopresis (fecal incontinence; 5%–15% of cases). Enuresis has been associated with obstructive sleep apnea, in which an increased level of atrial natriuretic factor has been reported. Atrial natriuretic factor inhibits the renin-angiotensin-aldosterone pathway, causing diuresis. Correcting obstructive sleep apnea with tonsillectomy or adenoidectomy can lead to the elimination of enuresis. Enuresis has a familial basis, with 44% being enuretic if 1 parent was enuretic and as many as 77% of children being enuretic if both parents were similarly affected. Concordance for enuresis is reported in up to 68% of monozygotic twins and between 36% and 48% of dizygotic twins.
A history of enuresis may be obtained as a presenting symptom or elicited by physicians during a health supervision visit. Medical conditions such as encopresis, obstructive sleep apnea (nighttime snoring), or ADHD may be associated with enuresis (Box 55.1). Children with ADHD have a 30% greater risk of being enuretic compared with their peers who do not have ADHD. The physical examination is usually normal.
Delayed control of micturition has several possible causes (Box 55.2).
•Faulty toilet training may perpetuate diurnal and nocturnal enuresis but is not expected to selectively perpetuate the latter. Parental expectations are believed to play a role in the toilet-training experience. Parents who allow children to sleep in overnight diapers or pull-ups may delay the achievement of nighttime dryness, but it is unlikely that the use of diapers or pull-ups causes nocturnal enuresis. Poor toilet habits, particularly infrequent voiding or constipation, may be associated with urinary tract infections (UTIs) and account for secondary enuresis.
Box 55.1. Diagnosis of Enuresis in Pediatric Patients
•Old enough to be toilet trained
•Bowel and bladder dysfunction
•Precipitating problem, such as diabetes or urinary tract infection
•Family history of enuresis
Box 55.2. Causes of Enuresis
•Faulty toilet training
•Small bladder capacity
•Sleep disorder/impaired arousal
•Nocturnal polyuria/relative vasopressin deficiency
•Dysfunctional bladder contraction
•Urinary tract infection
•Sickle cell anemia
•Maturational delay. The development of the inhibitory reflex of voiding may be delayed in some children, which may contribute to enuresis until the age of 5 years. This is similar to the range in which children achieve other developmental milestones. It is unlikely that maturational delay persists as a cause of enuresis beyond this age. Experts believe that maturational delay is not a reasonable explanation if children can achieve dryness in the daytime but not at night.
•Small bladder capacity. Evidence suggests that some children with enuresis have smaller than normal bladder capacities. Bladder capacity in ounces is estimated as the age in years plus 2. For example, 5-year-olds have a bladder capacity of 7 oz (210 mL). Adult bladder capacity is 12 to 16 oz (360–480 mL). Small bladder capacity is associated with diurnal frequency or incontinence.
•Sleep disorder/impaired arousal. The relationship between enuresis and sleep has been the focus of numerous studies, some with conflicting results. It has been suggested that children with enuresis are in “deep sleep” and do not sense a full bladder. This is often the parent’s perception of their child’s sleep pattern. However, studies have shown that enuresis occurs during all stages of sleep, particularly in the first one-third of sleep and in transition from non-rapid eye movement (non-REM) stage 4 to rapid eye movement (REM) sleep. During this period, body tone, respiratory rate, and heart rate increase, and erection and micturition occur. Studies suggest that the arousal center in the brain fails to respond (ie, the child does not awake) to full bladder sensation. Children with enuresis do not seem to sleep more deeply than other children. However, children with enuresis may have diminished arousal during sleep. In one study, 40% of children with enuresis, compared with only 8.5% of children without enuresis, did not awaken to an 80-dB noise. Other studies highlight the association of nocturnal enuresis with fragmented sleep, a lower proportion of motionless sleep, and more nighttime awakenings.
Recent studies suggest a correlation between nocturnal enuresis and periodic limb movement disorder. This disorder consists of involuntary movement of the lower extremities (ie, knee, hip, or ankle) during non-REM sleep. Periodic limb movement disorder is related to dopamine-depletion, leading to the disinhibition of spinal-cord motor and sensory reflexes. Dopamine deficit may affect the micturition center in the brain, leading to increased bladder contractions; hence, the association with enuresis.
•Allergens. No evidence confirms the notion that exposure to certain foods (eg, food additives, sugar) contributes to enuresis. However, some parents believe that bed-wetting is decreased if certain foods, such as sodas and sweets, are eliminated from the diet. The ingestion of caffeine-containing beverages may exacerbate nocturnal enuresis through the diuretic effect of caffeine.
•Nocturnal polyuria/relative vasopressin deficiency. Research has shown that although children who do not have enuresis exhibit a diurnal variation in arginine vasopressin (AVP) secretion, this rhythm is disturbed in some children with enuresis, resulting in nocturnal polyuria. In addition to regulating urine formation, AVP also regulates circadian rhythm. Dysregulation of AVP can, therefore, be associated with nocturnal polyuria as well as disturbed sleep.
•Dysfunctional bladder contraction. In cases of daytime incontinence, contractile disturbances of the bladder affect normal voiding. Children with an “uninhibited bladder” have not learned to inhibit bladder contraction. They may assume a certain posture, called Vincent curtsy, in an effort to prevent micturition. Some children exhibit uncoordinated, incomplete voiding and the urine exits the urethra in a staccato stream. Trabeculations or bladder wall thickening may be noted on imaging studies.
Daytime incontinence can be related to problems with bladder filling and storage or to bladder emptying. Each of these functions is under different neurologic control, with filling and storage under the sympathetic nervous system and bladder emptying related to the action of acetylcholine and the parasympathetic system. Effective voiding requires the coordinated effort of these 2 phases. Management of daytime incontinence is dependent on which phase is malfunctioning.
The differential diagnoses for both primary and secondary nocturnal enuresis are noted in Box 55.1. A specific organic problem is rarely the cause of primary nocturnal enuresis, although abnormal AVP regulation may affect some children. However, secondary enuresis may result from an organic problem, such as UTI, diabetes mellitus, diabetes insipidus, nocturnal seizures, genitourinary anomalies (eg, ectopic ureter), sickle cell anemia, medication use (eg, diuretics, theophylline, lithium), or emotional stress. When primary enuresis is diurnal and nocturnal, some of these conditions should be considered. Additional diagnoses include neurogenic bladder, which may occur in association with cerebral palsy; sacral agenesis; and myelomeningocele. Some children experience urinary frequency, a benign self-limited condition characterized by the sudden need to urinate very frequently, often 25 to 30 times a day. The condition occurs most often in children between 3 and 8 years of age, is self-limited, and is felt to be stress related. A urinary diary, noting time and amount of voiding, is sometimes helpful in diagnosing the condition.
A thorough history should be obtained when evaluating children with enuresis (Box 55.3). It may be helpful for the child or family to keep a diary recording the episodes of nocturnal enuresis over several weeks to a month. It may be useful to note the time the child ate dinner, what was eaten, and the time the child went to bed to help determine if there is any discernible pattern or contributing environmental factors.
A general physical examination should be performed, with particular attention to certain areas. The pattern of growth should be plotted. Blood pressure should be obtained. The abdomen should be assessed for evidence of organomegaly, bladder size, and fecal impaction. An anal examination should be performed to evaluate rectal tone.
Box 55.3. What to Ask
•Is the enuresis primary or secondary?
•Is the enuresis diurnal, nocturnal, or both?
•How old was the child when toilet training occurred?
•How old was the child when daytime and nighttime dryness was achieved?
•How often does the child urinate and defecate during the average day?
•Is the child’s urinary stream forceful or dribbling?
•Does the child dribble before or after voiding?
•Does the child experience symptoms such as polydipsia, polyuria, dysuria, urgency, frequency, or problems with passing stool?
•Who changes the bed and who washes the bedclothes after bedwetting occurs?
•Does the child wear diapers or pull-ups or use incontinence pads overnight?
•Does the child seem to delay using the toilet?
•Does the child assume any unusual or distinct postures to avoid being incontinent?
•What is the attitude of the family toward the child with enuresis? Are family members accepting or ashamed?
•Has the family tried any treatments yet?
•Is there a family history of enuresis?
•Does the child have other symptoms, such as encopresis, attention-deficit/hyperactivity disorder, or obstructive sleep apnea?