eMedicine Specialties > Pediatrics: Surgery > Urology

Enuresis

Author: Wm Lane M Robson, MA, MD, FRCP, FRCP(Glasg), Medical Director, The Children's Clinic
Contributor Information and Disclosures

Updated: Aug 31, 2009

Introduction

Background

The word enuresis is derived from a Greek word that means "to make water." In North America, the term is used to refer to wetting by night or day. Enuresis can be divided into primary enuresis (PE) and secondary enuresis (SE). A child who has experienced a minimum 6-month period of continence before the onset of the bedwetting is considered to have SE.

Psychological and social impact

In PE, psychological problems are almost always the result and only rarely the cause. By contrast, psychological problems are a possible cause in SE. The comorbidity of behavioral problems is 2-4 times higher in children with enuresis in all epidemiologic studies. The emotional impact of enuresis on a child and family can be considerable. Children with enuresis are commonly punished and are at significant risk of emotional and physical abuse. Numerous studies report feelings of embarrassment and anxiety in children with enuresis; loss of self-esteem; and effects on self-perception, interpersonal relationships, quality of life, and school performance.¹ A significant negative impact on self-esteem is reported even in children with enuretic episodes as infrequent as once per month.

Pathophysiology

Normal achievement of continence

Dryness at night usually follows achievement of continence by day. The table below shows the percentage of American children who achieve day and nighttime continence at varying ages.

During the second year of life, children start to develop the ability to voluntarily relax the external urethral sphincter and initiate voiding, even in the absence of the desire to void. By approximately age 4 years, all children with normal bladder function should have acquired this ability.

Table 1. Percent of Children Dry by Day and Night at Various Preschool Ages

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Genetics

Numerous studies report varying but high prevalence of the condition in other family members of patients with enuresis. The highest reported familial prevalence rates concluded that 56% of fathers, 36% of mothers, and 40% of siblings experienced a problem with enuresis. Enuresis is reported in 43% of children of enuretic fathers, 44% of children of enuretic mothers, and 77% of children when both the mother and father had enuresis. A family history of bedwetting is found in approximately 50% of children with SE.

Enuresis is usually transmitted in an autosomal dominant fashion. Chromosome 22 was identified as the site of enuresis locus in a Danish family in 1995.² Subsequent reports link enuresis in other families to loci chromosomes 8, 12, and 16.³

Identified genes cannot control for enuresis per se. Rather, an identified gene would need to control a pathophysiological factor such as arousal, nocturnal polyuria, or bladder capacity.

Frequency

United States

The prevalence of PE in the United States varies by age. By age 4 years, 25% of children frequently wet the bed. By age 7 years, only 5%-10% still wet the bed. Less that 5% of children wet the bed by age 10 years. The resolution rate of PE is approximately 15% per year; by the late teenaged years, very few patients have the condition.

International

The prevalence of PE seems to be the same throughout the world, although no standardized evaluation of the incidence of bedwetting has been made on a global basis.

Mortality/Morbidity

Mortality attributable directly to enuresis has not been reported, but children with enuresis have been fatally abused by parents and other caregivers, and bedwetting was considered a "trigger" for the abuse in some situations. The morbidity, in terms of psychosocial stress, has been recognized in the psychiatric literature. Enuresis can also be associated with significant family stress. Punishment should be considered a potential morbid consequence of enuresis.

Severe perineal, genital, and lower abdominal rash may also occur in patients with enuresis, potentially leading to skin breakdown and, rarely, cutaneous infections.

Race

Enuresis has no racial predisposition.

Sex

• Enuresis is more common in males.
• The reported prevalence of enuresis in boys aged 7 and 10 years is 9% and 7%, respectively, compared with 6% and 3%, respectively, in girls.

Age

• The prevalence of enuresis gradually declines during childhood. Of children aged 5 years, 23% have enuresis. During elementary school years, the problem remains common, with 10% of 7-year-old children and 4% of 10-year-old children still experiencing enuresis. Of persons aged 18 years and older, approximately 1%-2% remain enuretic.
• When PE and SE are reported, a secondary onset accounts for approximately one fourth of cases. The prevalence of SE as a percentage of all cases of enuresis increases with age. In a cohort of New Zealand children, 7.9% developed SE by the time they were aged 10 years.⁴
• The prevalence of enuresis in adulthood is reported to be 0.5%-2%.

Clinical

History

• The best time to investigate enuresis is when the parent or patient first raises the issue in the physician’s office. However, the optimal time for treating enuresis should be based on the motivation of the child.
• The most important aspect of the investigation is a meticulous history, which can establish the diagnosis, lead to more precise treatment recommendations, and minimize the need for invasive and costly investigations.
• The history should include fluid intake, daytime voiding pattern, and number and time of episodes of bedwetting. When the history is not clear, request that the family record fluid intake, daytime voiding, and episodes of bedwetting for at least a 2-week period.
• A sleep history should include the times the child goes to bed, falls asleep, and awakens in the morning. Parents should be asked to subjectively comment on the depth of sleep of the child. The presence of restless sleep, snoring, and the type and frequency of nocturnal arousals (eg, nightmares, sleep terrors, sleepwalking) should be determined.
• The timing and number of wetting episodes should be determined.
• Whether the child has experienced periods of dryness and the circumstances of these episodes should also be determined.
• A diet history should include the timing, quantity, and type of fluid and solid food intake during the day and after supper. Many children with enuresis do not drink appreciable amounts of liquids during the school day, arrive home from school thirsty, and drink most of their daily fluids in the 4 or 5 hours before bed, a pattern that favors nocturnal production of urine.
• An assessment of the emotional impact on the child is important. Information should be solicited from both the parents and the child. Basic and revealing information includes whether the child has experienced teasing by family or friends or has self-restricted participation in school, sleepovers, or trips.
• Presence of common underlying problems is indicated by the following:
  • Patients with overactive bladder or dysfunctional voiding usually present with frequency, urgency, squatting behavior, and daytime and nighttime wetting. Constipation and cystitis are common associated problems in patients with overactive bladder or dysfunctional voiding.
  • Symptoms of cystitis include dysuria; cloudy, foul-smelling urine; visible blood in the urine; frequency; urgency; and day and nighttime wetting. Symptoms of cystitis can be very subtle in some children.
  • Constipation manifests as infrequent and painful passage of hard wide stool, encopresis, and colicky periumbilical pain.
  • Bowel-related problems and gait abnormalities are often present in patients with neurogenic bladder.
  • Symptoms of sleep disordered breathing (SDB) include snoring, mouth breathing, lack of restful sleep, and tiredness the following morning.
  • The hallmark symptoms of urethral obstruction are the need to wait or push to initiate voiding and a weak or interrupted stream.
  • When bedwetting is a feature of a major motor seizure, parents may hear nocturnal sounds associated with abnormal muscle movements.
  • Girls with ectopic ureter are always wet.
  • Symptoms of diabetes mellitus include polyuria, polydipsia, and weight loss notwithstanding a voracious appetite.
  • Patients with diabetes insipidus present with polyuria, polydipsia, and symptoms related to the underlying hypothalamic or renal causes.

Physical

• A comprehensive physical examination is important. The examination should include the following:
  • Measurement of blood pressure
  • Inspection of external genitalia
  • Palpation in the renal and suprapubic areas to look for enlarged kidneys or bladder
  • Thorough neurologic examination of the lower extremities, including gait, muscle power, tone, sensation, reflexes, and plantar responses.
  • Inspection and palpation of the lumbosacral spine
• Abnormal physical findings are usually absent in children when enuresis is the sole symptom and are not necessarily present in children with overactive bladder or dysfunctional voiding.
• Abnormal physical findings may be found in patients with cystitis, constipation, neurogenic bladder, urethral obstruction, ectopic ureter, obstructive sleep apnea (OSA), and hyperthyroidism.
• A spinal defect, such as a dimple, hair tuft, or skin discoloration, might be visible in approximately 50% of patients with an intraspinal lesion.
• Assessment of the anal wink or the ability of a patient to stand on the toes is a satisfactory test of the integrity of the S2-4 spinal reflex arc.
• In some situations, observing the child void is helpful to assess the urinary stream. If the child grunts audibly or uses the abdominal muscles to push or if the stream is weak or interrupted, a urethral obstruction might be present.
• In girls with ectopic ureter, a constant moistness is observed in the introitus, and regular drying with tissue reveals the persistent leak of urine.
• Tonsillar size in a child examined in the awake and sitting position may not correlate with OSA symptoms. Examination of the child in the prone position and during sleep may be necessary to visibly document obstruction.
• Palpation of the thyroid is important if hyperthyroidism is suspected.

Causes

Table 2. Causes of Primary and Secondary Enuresis

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• Idiopathic: If no cause can be identified, the important pathophysiologic factors include a disorder of sleep arousal, nocturnal polyuria, and a low nocturnal bladder capacity.
• Disorder of sleep arousal
  • Studies reveal that children with enuresis do not wake up normally in response to an auditory signal; these studies confirm a defect in arousal.
  • Arousal to the sensation of a full or contracting bladder involves interconnected anatomic areas, including the cerebral cortex, reticular activating system (RAS), locus ceruleus (LC), hypothalamus, pontine micturition center (PMC), spinal cord, and bladder. The RAS controls depth of sleep, the LC controls arousal, and the PMC initiates the command for a detrusor contraction. Various neurotransmitters are involved, including noradrenaline, serotonin, and antidiuretic hormone (ADH).
• Nocturnal polyuria
  • Factors that cause nocturnal polyuria in children with enuresis include the following:
    • Fluid ingestion before bedtime
    • Food consumption before bedtime
    • Low nocturnal secretion of ADH
    • Increased nocturnal solute excretion
    • Excess intake of caffeine
  • Studies reveal nocturnal polyuria in some but not all children with enuresis.
  • Although nocturnal polyuria is important in the pathophysiology of enuresis, overproduction of urine per se cannot be the sole causal factor. Nocturnal polyuria does not explain why children with enuresis do not wake up to the sensation of a full or contracting bladder or enuresis that occurs during daytime naps.
  • Nocturnal polyuria likely has multiple causes.
  • Ingestion of fluids prior to bedtime is a common cause. Solid food ingestion is also a cause because excretion of solute by the kidney is accompanied by an obligate amount of water.
  • Production of urine is controlled by several factors, including ADH, which directly controls water absorption, and atrial natriuretic peptide (ANP) and aldosterone, which control solute and, therefore, indirectly affect water excretion.
  • Norgaard et al were the first to report absence of the expected nocturnal increase in ADH secretion in children with enuresis.⁵ Subsequent reports suggest that low nocturnal secretions of ADH are present in some but not all children with enuresis.
  • Urine sodium and potassium excretion are increased in some children with enuresis, but the reasons for these observations are not clear. Rittig et al report that secretion of ANP in children with enuresis shows a normal circadian rhythm, and the renin-angiotensin-aldosterone system is intact.⁶
  • Bladder distension may influence nocturnal secretion of ADH. Some studies report that ADH secretion is increased in response to bladder distension and reduced with bladder emptying. If ADH secretion falls with bladder emptying, the observed low nocturnal blood levels of ADH may be a consequence rather than a cause of enuresis.
• Low nocturnal bladder capacity
  • Small functional bladder capacity is a long-suspected pathophysiologic factor for enuresis. Until recently, this theory was considered a less likely explanation for enuresis in children without daytime symptoms. The literature includes reports of normal and reduced functional bladder capacity, but few studies report on carefully selected patients with only enuresis. Daytime urodynamic studies in carefully selected children with enuresis but without daytime symptoms have reported results within the reference range; however, urodynamic studies during sleep reveal that some of these children have a low nocturnal bladder capacity. The reasons for the diurnal-nocturnal difference are not clear.
  • In a study by Mattsson and Lindstrom, functional bladder capacity (FBC) was positively correlated with nighttime urine output.⁷ Children with enuresis possibly maintain a smaller nocturnal bladder volume, and this situation may condition the detrusor to contract at a lower volume. According to this theory, the low nocturnal bladder capacity is a consequence rather than a cause of enuresis.
  • Bloom et al suggest a problem with the external urethral sphincter as a possible cause of low nocturnal bladder capacity.⁸ These authors suggest that the control of voiding rests at the external urethral sphincter, where constant activity is present as a guarding reflex to preserve continence. They speculate that the activity of the external urethral sphincter might fall below a critical level during sleep and thereby trigger a detrusor contraction.
• Overactive bladder/dysfunctional voiding
  • Overactive bladder/dysfunctional voiding is more common in preschool- and elementary school–aged girls and usually presents with urinary frequency, urgency, squatting behavior, daytime wetting, and enuresis.
  • Squatting behavior, a common and distinct symptom of overactive bladder/dysfunctional voiding, is a learned response and an attempt to suppress an unexpected and unwelcome detrusor contraction. The squatting posture elicits a bulbar detrusor inhibitory reflex.
  • In some children, a period of normal voiding occurs, and the onset of the bedwetting is compatible with SE.
  • If enuresis is present, the cause is presumed to be a low nocturnal bladder capacity, but a disorder of arousal might also be present.
  • Symptoms tend to improve or resolve with time and are less common after puberty. Vesicoureteral reflux is more common in these children, and cystitis and constipation are frequent complicating problems. Urodynamic studies reveal unstable detrusor contractions early in the filling phase.
• Cystitis
  • Cystitis is a common cause of enuresis and an aggravating factor associated with other causes. Cystitis associated with enuresis might present at any age.
  • Cystitis causes uninhibited detrusor contractions that can lead to episodes of day and nighttime wetting.
  • If cystitis is the only cause of enuresis, other symptoms of infection are usually present, and the wetting resolves with an appropriate antibiotic.
  • Cystitis is more common in children with overactive bladder/dysfunctional voiding, neurogenic bladder, urethral obstruction, ectopic ureter, and diabetes mellitus. In these conditions, daytime symptoms do not resolve completely with antibiotic treatment.
• Psychological causes
  • Various common situations predispose to a psychological cause, including birth of a new sibling, parental divorce or separation, a death in the family, child abuse, or any other cause of social dysfunction at home or school.
  • von Gontard et al found that children with SE have a significantly higher rate of behavioral disorders, life events, and continuous psychosocial stress than those with PNE.⁹
  • Stressful life events and psychiatric diagnoses are reported to precede the diagnosis of SE. The later the onset of SE, the more likely the possibility of preceding psychological stress.
• Constipation
  • Constipation can cause both PE and SE and is a common aggravating factor that should be considered when other causes are present.
  • Although the mechanism is not clear, the pressure effect of stool in the descending or sigmoid colon possibly can trigger an uninhibited detrusor contraction. Constipation is usually present in children with neurogenic bladder and is more common in those with overactive bladder and dysfunctional voiding.
• Sleep disordered breathing
  • SDB is a disorder associated with both an abnormality in arousal and enuresis. The most common cause of SDB in childhood is adenotonsillar hypertrophy, which has a peak incidence in children aged 2-5 years.
  • The dramatic resolution of enuresis following surgical treatment of airway obstruction suggests SDB influences a critical pathophysiologic factor. A disorder of sleep arousal is suggested as the most likely factor. Nocturnal polyuria is reported in individuals with OSA and is another possible causative factor. A decrease in nocturnal secretion of ADH and increase in ANP are possible explanations for nocturnal polyuria.
• Neurogenic bladder
  • A neurogenic bladder can develop because of a lesion at any level in the nervous system, including the cerebral cortex, the spinal cord, or the peripheral nerves. As many as 37% of children with cerebral palsy have enuresis.
  • Patients with myelomeningocele almost always have enuresis. Other spinal cord abnormalities, such as caudal regression syndrome, tethered cord, tumors, anterior spinal artery syndrome, and spinal cord trauma, can cause enuresis.
  • Specific dysfunction in the external urethral sphincter can develop after pelvic extirpative surgery, radiation therapy for pelvic malignancy, pelvic fracture, and incontinence surgery.
  • Sacral agenesis can be associated with a neurogenic bladder. As many as 5% of patients with an imperforate anus have a neurogenic bladder, and most patients also have a lumbosacral anomaly.
• Urethral obstruction
  • Urethral obstruction can be congenital, such as with posterior urethral valves, congenital stricture, or urethral diverticula, or acquired because of a traumatic or infectious stricture. Traumatic strictures may develop after a traumatic urethral catheterization, a foreign body in the urethra, or pelvic trauma.
  • Infectious strictures are a complication of purulent urethritis due to bacteria such as Neisseria gonorrhoeae.
  • Meatal stenosis is a common cause of distal urethral obstruction in circumcised males.
• Seizure disorder
  • SE may be a symptom of an unobserved overnight major motor convulsion in a child with a known seizure disorder.
  • New-onset seizures rarely occur only at night, and bedwetting is, therefore, a rare manifestation.
• Ectopic ureter
  • This rare congenital abnormality is due to the insertion of the ureter in a location other than the lateral angle of the bladder trigone. Enuresis results when the insertion is distal to the external urethral sphincter.
  • Ectopic ureter is 3-4 times more common in girls than in boys and causes incontinence only in females.
  • The most common site of the ectopic orifice is adjacent to the external urethral meatus and is below the external sphincter in females.
• Diabetes mellitus
  • Enuresis is usually not the presenting complaint in a child with new-onset diabetes mellitus. Conventional symptoms of insulin deficiency usually overshadow the presence of bedwetting.
  • SE in a child with established diabetes mellitus may be a symptom of suboptimal control with nocturnal polyuria due to hyperglycemia. Although nocturnal polyuria is presumed to be the cause of the bedwetting, a disorder of arousal is also likely present because most school-aged patients develop nocturia but maintain a dry bed.
  • Diabetes mellitus is also associated with abnormalities in the afferent sensory pathways to the bladder, which may contribute to enuresis.
• Diabetes insipidus
  • Diabetes insipidus is an uncommon cause of enuresis. Although nocturnal polyuria is often presumed to be the cause of bedwetting, a disorder of arousal may also be present.
  • Diabetes insipidus may be central or nephrogenic. Central diabetes insipidus may result from an intracranial tumor, head trauma, encephalitis, or meningitis. Nephrogenic diabetes insipidus may result from any cause of renal failure, diffuse renal cortical or medullary damage, hypokalemia, hypercalcemia, or nephrotoxic drugs.
• Heart block
  • Very rarely, SE may be secondary to heart block.
  • Berul and Murphy reported a 4-year-old boy with SE associated with third-degree atrioventricular block.¹⁰ Following implantation of a ventricular demand pacemaker, the bedwetting resolved. The authors speculated that the SE was due to a problem with arousal consequent to nocturnal bradycardia and hypoxia.
• Hypothyroidism: Kozeny and Wood reported a 17-year-old boy with hypothyroidism and SE.¹¹ The SE resolved with attainment of a euthyroid state.

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