Nocturnal enuresis in children: Etiology and evaluation

INTRODUCTION — Urinary incontinence is a common problem in children. At five years of age, 15 percent of children are incompletely continent of urine. Most of these children have isolated nocturnal enuresis (monosymptomatic nocturnal enuresis).

The causes and evaluation of nocturnal enuresis in children will be presented here. The management of nocturnal enuresis and bladder dysfunction are discussed separately. (See "Nocturnal enuresis in children: Management" and "Etiology and clinical features of bladder dysfunction in children" and "Evaluation and diagnosis of bladder dysfunction in children" and "Management of bladder dysfunction in children".)

TERMINOLOGY — The International Children's Continence Society has developed standardized terminology for lower urinary tract function and malfunction in children [1,2].

●Enuresis – Enuresis (synonymous with intermittent nocturnal incontinence) refers to discrete episodes of urinary incontinence during sleep in children ≥5 years of age [1]. Enuresis is divided into monosymptomatic and non-monosymptomatic forms, although the pathogenesis and evaluation of the two forms overlap [3,4].

•Monosymptomatic enuresis – Monosymptomatic enuresis is defined as enuresis in children without any other lower urinary tract symptoms and without a history of bladder dysfunction [1]. Monosymptomatic nocturnal enuresis usually is divided into primary and secondary forms.

-Primary enuresis – Children who have never achieved a satisfactory period of nighttime dryness have primary enuresis. An estimated 80 percent of children with nocturnal enuresis have primary enuresis.

-Secondary enuresis – Children who develop enuresis after a dry period of at least six months have secondary enuresis [5].

Secondary enuresis often is ascribed to an unusually stressful event (eg, caregiver divorce, birth of a sibling) at a time of vulnerability in a child's life. Stool retention and suboptimal daytime voiding habits often play a role. However, the exact cause of secondary enuresis may remain unknown.

•Non-monosymptomatic enuresis – Non-monosymptomatic enuresis is defined as enuresis in children with other lower urinary tract symptoms, including [1]:

-Consistently increased (≥8 times/day) or decreased (≤3 times/day) voiding frequency

-Daytime incontinence

-Urgency

-Hesitancy (difficulty initiating voiding)

-Straining (application of abdominal pressure to initiate and maintain voiding)

-A weak stream

-Intermittency (micturition occurs in several discrete spurts)

-Holding maneuvers (strategies used to postpone voiding)

-A feeling of incomplete emptying

-Postmicturition dribble

-Genital or lower urinary tract pain

•Bladder dysfunction – Bladder dysfunction is a subset of non-monosymptomatic enuresis. Patients who have nocturnal enuresis with daytime symptoms are described as having bladder dysfunction (also called complex or complicated enuresis). Approximately 20 percent of children who have nighttime wetting also have significant daytime symptoms [6].

The daytime symptoms may be limited to urgency and frequency but often include incontinence. Urologic (eg, detrusor instability, recurrent urinary tract infection) and neurologic disorders (eg, spinal dysraphism) are more common among children with daytime symptoms than those with monosymptomatic enuresis [7].

•Bowel and bladder dysfunction – Children who have associated urinary and bowel symptoms often are described as having bowel and bladder dysfunction. Approximately 15 percent of children with nighttime wetting also have troublesome fecal incontinence.

This topic review will focus on the causes and evaluation of monosymptomatic enuresis in children. Bladder dysfunction is discussed separately. (See "Etiology and clinical features of bladder dysfunction in children" and "Evaluation and diagnosis of bladder dysfunction in children" and "Management of bladder dysfunction in children".)

EPIDEMIOLOGY AND NATURAL HISTORY — Monosymptomatic nocturnal enuresis is common in children. The prevalence varies according to age (figure 1) [8-10]:

●5 years – 15 percent

●6 years – 13 percent

●7 years – 10 percent

●8 years – 7 percent

●10 years – 5 percent

●12 to 14 years – 2 to 3 percent

●≥15 years – 1 to 2 percent

Monosymptomatic nocturnal enuresis is twice as common among males as females. It resolves spontaneously at a rate of approximately 15 percent per year [11,12]. The longer the enuresis persists, the lower the probability that it will spontaneously resolve [9,11].

NORMAL BLADDER MATURATION — Normal bladder function depends upon a complex interrelationship between autonomic and somatic nerves, which are integrated at various sites in the spinal cord, brainstem, midbrain, and higher cortical centers (figure 2). The complex coordination permits urine storage at low pressure with high outlet resistance and voiding with low outlet resistance and sustained detrusor (bladder wall muscle) contraction.

At birth, bladder function is thought to be coordinated through the lower spinal cord and/or primitive brain centers. Voiding at this stage is efficient but uncontrolled. Uninhibited contraction is caused by progressive and sustained bladder filling. Voiding in the newborn also may be initiated by neurologically stimulating activities, such as feeding, bathing, tickling, etc.

During the first three years of life, bladder capacity increases disproportionately relative to body surface area. By four years of age, most children void five to six times per day [13,14].

Development of bladder control appears to follow a progressive maturation. The child first becomes aware of bladder filling, then develops the ability to suppress detrusor contractions voluntarily and, finally, learns to coordinate sphincter and detrusor function. These skills usually are achieved, at least during the day, by approximately four years of age. Nighttime bladder control is achieved months to years after daytime control but is not expected until five to seven years of age [15,16].

Incomplete development of bladder control results in more complex wetting problems that almost always are associated with daytime incontinence. These include bladder dysfunction, overactive bladder, underactive bladder, recurrent urinary tract infections, and some cases of vesicoureteral reflux. (See "Etiology and clinical features of bladder dysfunction in children", section on 'Daytime urinary incontinence' and "Etiology and clinical features of bladder dysfunction in children", section on 'Associated conditions'.)

PATHOGENESIS — Nocturnal enuresis occurs when the child does not wake to void [17]. In any given child, this may result from one or a combination of several related factors, including maturational delay, genetic factors, nocturnal polyuria, disturbed sleep, small bladder capacity, and detrusor overactivity [3,18-21]. Psychological and behavioral abnormalities appear to be a result, rather than a cause, of enuresis [22-24]. (See 'Associated conditions' below.)

●Maturational delay – In almost all cases, monosymptomatic nocturnal enuresis resolves spontaneously (figure 1). This observation suggests that delayed maturation of a normal developmental process plays a role in nocturnal enuresis [25-27]. Some studies have demonstrated an increased incidence of delayed language and gross motor development and slowed motor performance among children with enuresis [28,29]. The hypothesis that there is a difference in the central nervous system (CNS) maturation in children with primary enuresis compared with controls is supported by neurophysiologic data [30-32].

Enuretic episodes are associated with characteristic urodynamic and electroencephalographic (EEG) findings. Many children who have enuresis are noted to have progressive maturation of bladder stability in conjunction with EEG findings that suggest increased CNS recognition of bladder fullness and the ultimate ability to suppress the onset of bladder contraction [32]. These findings support the hypothesis that delayed maturation of bladder control plays a role in monosymptomatic nocturnal enuresis.

●Genetic factors – There is a genetic tendency toward nocturnal enuresis. The concordance among monozygotic twins is almost twice that among dizygotic twins (68 versus 36 percent) [33]. When one parent has a history of prolonged nighttime wetting, approximately 50 percent of the offspring are affected; when both parents have a history, approximately 75 percent of offspring are affected [34]. On the other hand, when neither parent has a history of nocturnal enuresis, only 15 percent of offspring are affected. An autosomal dominant form of primary nocturnal enuresis with a penetrance greater than 90 percent has been identified in Danish families and linked to a locus on chromosome 13q13-q14.3 (MIM %600631) [35]. Additional genetic loci associated with enuresis have been identified on chromosomes 12q13-q21 (MIM %600808), 13q22.3, 22q11, and 6q16.2 [21,36].

●Nocturnal polyuria and antidiuretic hormone – Increased nighttime urine output appears to play an important role in nocturnal enuresis, although it does not explain why the children do not wake to void [3,37,38].

Clinical findings suggestive of or associated with nocturnal polyuria include consumption of the majority of fluids during the late afternoon and evening, soaking of or through absorbent underpants, and large-volume first morning void despite nocturnal enuresis [39].

Mechanisms for increased nighttime urine output may include increased fluid intake before bedtime [39], reduced response to antidiuretic hormone (ADH), and/or decreased secretion of ADH [40-44]. The relationship between ADH secretion and nighttime urinary flow rates is debated. In children who do not have enuresis, urine output decreases during the night because the secretion of ADH and other regulatory hormones follows a circadian pattern, with increased secretion at night [45-47]. Observational studies suggest that abnormalities in ADH play a role in at least some children with ADHD [40-44], but it is not clear whether these abnormalities are primary or secondary (eg, to bladder capacity or maturational delay) [48,49].

●Disturbed sleep – Whether abnormally deep sleep contributes to enuresis is controversial. Caregivers often describe their children with enuresis as excessively deep sleepers [20,50,51]. This may be a bias of observation since caregivers rarely attempt to wake children without enuresis. Nonetheless, in one sleep laboratory study of 33 males aged 7 to 12 years (15 with enuresis and 18 age-matched controls), attempts at arousal were more often successful in control subjects than in males with enuresis (40 versus 9 percent) [52]. Excessively deep sleep also appears to contribute to nocturnal enuresis in adolescents and adults [53].

Another sleep study found that children with severe and refractory enuresis (≥5 wet nights/week) slept more lightly than controls but did not wake before voiding [54]. Subjects with enuresis had frequent cortical arousals but inability to waken completely. The cortical arousals were associated with unstable bladder contractions, suggesting to the authors that the arousal center may be paradoxically suppressed by signals from the bladder.

Other sleep studies show that sleep patterns among children with and without enuresis are similar [55,56]. These studies indicate that enuretic episodes may occur at random throughout the night but primarily during nonrapid eye movement sleep [57]. However, some children wet during phases of early awakening.

●Small bladder capacity – At birth, bladder volume is approximately 60 mL (2 ounces); bladder volume increases with age at a relatively steady rate of approximately 30 mL (1 ounce) per year until 10 years of age. Normal bladder capacity (in ounces [1 ounce = 30 mL]) can be estimated by adding 2 to the child's age in years, until 10 years of age [58]. Children with nocturnal enuresis, even those who do not have daytime symptoms, have been noted to have a smaller bladder capacity than age-matched children who do not have nocturnal enuresis [59-63]. Clinical findings suggestive of reduced bladder capacity include urinary frequency and associated constipation or cystitis [39].

The reduced bladder capacity appears to be functional rather than anatomic. In an observational study, the average bladder capacity of children with enuresis in the awake state was lower than that in control children (135 versus 180 mL in children age 4 to 6 years, 165 versus 240 mL in children age 7 to 8 years, and 180 versus 360 mL in children age 9 to 11 years). However, the average bladder capacity of children with enuresis during general anesthesia was greater than when they were awake (206 versus 135 mL in children age 4 to 6 years, 229 versus 165 mL in children age 7 to 8 years, and 283 versus 180 mL in children age 9 to 11 years) [64]. In another observational study, the maximal endurable bladder capacity during the daytime was similar between children with enuresis and controls [65]. However, among children with enuresis, the maximal voided volume during the night was significantly smaller than the maximal daytime bladder capacity, suggesting that inability to hold urine during sleep plays a role in nocturnal enuresis.

●Detrusor overactivity – Although detrusor abnormalities are more frequently associated with daytime urinary incontinence, detrusor overactivity should be considered in children with refractory monosymptomatic nocturnal enuresis [66]. They may have a defect in the circadian rhythm of detrusor inhibition and/or pelvic floor activity [67]. (See "Etiology and clinical features of bladder dysfunction in children", section on 'Daytime urinary incontinence'.)

Most studies suggest that the incidence of uninhibited bladder activity in children with primary monosymptomatic nocturnal enuresis is similar to the incidence of uninhibited activity in children without enuresis (between 3 and 5 percent) [68-70]. However, when urodynamic studies are performed during sleep, the only difference between children with and without enuresis is the increased rate of bladder contractions that occur in association with the enuretic episode [71]. In addition, urodynamic studies during sleep demonstrate a relationship between nocturnal enuresis and pelvic floor activity. When pelvic floor activity increased in association with detrusor contractions, wetting was usually avoided, and the patient would often awaken subsequently to void. In contrast, when pelvic floor activity did not increase, the detrusor contraction usually was associated with a wetting episode [72,73].

ASSOCIATED CONDITIONS — Nocturnal enuresis may be associated with neurodevelopmental problems, including intellectual disability, autism spectrum disorder, and attention deficit hyperactivity disorder [74-77]. Disturbed sleep may contribute to or exacerbate these problems [78]. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Clinical manifestations'.)

Although psychological abnormalities have been hypothesized to play a role in the pathogenesis of nocturnal enuresis, this relationship is unproven. Perceived adjustment problems and low self-esteem tend to improve after resolution of enuresis, suggesting that the behavioral abnormalities are a result of the enuresis rather than a cause [22-24,79]. Children whose enuresis has resolved do not develop other behavioral or mental health symptoms [80].

CAUSES OF NOCTURNAL ENURESIS — Other causes of nocturnal enuresis that may require additional evaluation and/or treatment should be considered in children with enuresis. These conditions usually can be identified through the history, physical examination, and urinalysis.

They include [62,81-83] (table 1):

●Bladder dysfunction (usually associated with daytime symptoms (table 2)) (see "Etiology and clinical features of bladder dysfunction in children", section on 'Daytime urinary incontinence')

●Urinary tract infection (UTI, associated with pyuria or bacteriuria on urinalysis) (see "Urinary tract infections in infants and children older than one month: Clinical features and diagnosis", section on 'Older children')

●Chronic kidney disease (associated with poor growth or weight loss, hypertension, abnormal urinalysis [eg, proteinuria, hematuria], edema, and with progressive deterioration of kidney function, anorexia, vomiting, weakness, and fatigue) (see "Chronic kidney disease in children: Clinical manifestations and evaluation", section on 'Clinical manifestations')

●Posterior urethral valves (associated with incomplete bladder emptying [noted through palpation or percussion of the bladder], straining to void, large volumes of voided urine, slow or intermittent urinary stream, dribbling of urine, UTIs, poor weight gain) (see "Clinical presentation and diagnosis of posterior urethral valves", section on 'Clinical manifestations')

●Ectopic ureter in females (associated with persistent dampness in underwear and absence of dry episodes) (see "Ectopic ureter", section on 'Clinical presentation')

●Fecal incontinence or constipation (associated with fecal soiling, infrequent stooling, and palpation of stool in the abdomen) (see "Functional fecal incontinence in infants and children: Definition, clinical manifestations, and evaluation", section on 'Clinical manifestations' and "Constipation in infants and children: Evaluation", section on 'Constipation and bladder dysfunction')

●Sickle cell disease (may be associated with positive family history, abnormal urinalysis [decreased specific gravity, hematuria, proteinuria]) (see "Overview of the clinical manifestations of sickle cell disease", section on 'Kidney complications')

●Seizures (associated with paroxysmal, stereotyped behaviors [eg, staring, limb movements, loss of tone]) (see "Seizures and epilepsy in children: Classification, etiology, and clinical features", section on 'Clinical characteristics')

●Diabetes mellitus (associated with polyuria, polydipsia, weight loss, and glucosuria)

●Arginine vasopressin disorders, previous called diabetes insipidus (associated with polyuria, polydipsia, and decreased specific gravity on first morning void)

●Spinal dysraphism (see "Myelomeningocele (spina bifida): Anatomy, clinical manifestations, and complications", section on 'Spinal cord')

●Obstructive sleep apnea [84-88] (see "Evaluation of suspected obstructive sleep apnea in children", section on 'Evaluation')

●Pinworms (associated with perianal excoriation) [89,90] (see "Enterobiasis (pinworm) and trichuriasis (whipworm)", section on 'Clinical manifestations' and "Enterobiasis (pinworm) and trichuriasis (whipworm)", section on 'Diagnosis')

●Primary polydipsia (sometimes called psychogenic polydipsia; associated with polyuria) (see "Evaluation of patients with polyuria", section on 'Primary polydipsia')

EVALUATION — The evaluation of the child with monosymptomatic nocturnal enuresis includes history, physical examination, and urinalysis. The history, including a voiding diary (form 1), is the mainstay of the evaluation [3,39,91].

Goal — The main goal of the evaluation is to determine whether the child has bowel and bladder dysfunction or enuresis as a manifestation of an underlying medical problem (eg, posterior urethral valves or other anatomic abnormality, spinal dysraphism, diabetes) (table 1) [3]. Additional evaluation may be necessary to exclude or confirm these disorders. (See 'Causes of nocturnal enuresis' above.)

History — Important issues to be considered in the history include (table 3) [3,39,62,81,91,92]:

●Daytime wetting or lower urinary tract symptoms (table 2), including urgency, holding maneuvers, interrupted micturition, weak stream, and straining. Urologic and neurologic disorders are more common among children with daytime symptoms.

●Whether the child ever had a prolonged period of dryness (ie, six months).

●Frequency and trend of nocturnal enuresis (eg, number of wet nights per week or month, number of episodes per night, time of episodes).

●Fluid intake diary.

•Consuming the majority of fluids during the late afternoon and evening may be associated with nocturnal polyuria, which contributes to nocturnal enuresis (see 'Pathogenesis' above)

•Fluid intake that exceeds maintenance fluid requirements may indicate diabetes mellitus, arginine vasopressin disorders (previously called diabetes insipidus), or primary polydipsia

●Stooling history and history of soiling (to determine whether there is associated constipation or fecal incontinence, an important cause of secondary enuresis) [93]. (See "Constipation in infants and children: Evaluation".)

●Determination of which interventions the caregivers have tried and whether they were successful.

●Medical history (eg, review of systems for symptoms of sleep apnea, diabetes, sickle cell disease, urinary tract infection [UTI], gait or neurologic abnormalities).

●Family history of nocturnal enuresis.

●Social history (particularly important in secondary enuresis because somatic and psychological comorbidities are more common among children with secondary enuresis) [5,94].

●Assessment of how the problem has affected the child and family; the risk of treatment resistance is increased in children who are not bothered by their enuresis. Postponement of therapy until the child is motivated may be warranted.

●Developmental and behavioral histories and developmental-behavioral screening questionnaires (to screen for neurodevelopmental and behavioral/psychological comorbidities). (See "Developmental-behavioral surveillance and screening in primary care", section on 'Choice of screening test'.)

Voiding diary — Once significant stool retention has been addressed with a bowel program, a voiding diary (form 1) is helpful in identifying children with non-monosymptomatic enuresis or other conditions that may require additional evaluation or referral. (See "Chronic functional constipation and fecal incontinence in infants, children, and adolescents: Treatment", section on 'Treatment of constipation in children' and "Constipation in infants and children: Evaluation".)

The voiding diary should include [3,39,92]:

●Timing of daytime voids

●Volume of voided urine (to estimate bladder capacity)

●Lower urinary tract symptoms (eg, difficulty starting or stopping stream; dribbling; sensation of incomplete emptying)

Physical examination — The physical examination of the child with primary monosymptomatic nocturnal enuresis usually is normal. Aspects of the physical examination that may indicate an underlying medical etiology for enuresis are listed below (table 4) [3,39,92]:

●Poor growth and/or hypertension (table 5A-B) may indicate renal disease.

●Tonsillar hypertrophy or "adenoid facies" (figure 3) may indicate obstructive sleep apnea. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Examination'.)

●Detection of wetness in the undergarments is a sign of daytime incontinence.

●Palpation of stool in the abdomen suggests constipation or fecal incontinence; however, retained stool is not always palpable on abdominal examination.

●Perianal excoriation or vulvovaginitis may indicate pinworm infection. (See "Enterobiasis (pinworm) and trichuriasis (whipworm)".)

●Abnormalities of the lumbosacral spine (eg, abnormal tuft of hair or an abnormality in the gluteal fold (picture 1)) and/or abnormalities on neurologic examination of the perineum and lower extremities may indicate occult spinal cord abnormalities. (See "Myelomeningocele (spina bifida): Anatomy, clinical manifestations, and complications".)

●Detection of incomplete bladder emptying by percussion and/or palpation or observation of voiding that demonstrates slow urinary stream, dribbling, or intermittent stream, which may indicate urologic abnormalities such as posterior urethral valves. In females, persistent damp underwear without dry episodes may be indicative of an ectopic ureter. (See "Clinical presentation and diagnosis of posterior urethral valves", section on 'Clinical manifestations' and "Ectopic ureter", section on 'Clinical presentation'.)

Urinalysis — Urinalysis should be performed in all children with monosymptomatic enuresis [3]. The urinalysis (including specific gravity) is obtained as a screen for diabetic ketoacidosis, arginine vasopressin disorders (previously called diabetes insipidus), water intoxication, and/or occult UTI [39]. To screen for arginine vasopressin disorders (previously called diabetes insipidus) and possibly differentiate from water intoxication, the urinalysis should be performed on a first morning void. Urine culture is not necessary unless indicated by white blood cells or nitrites on urinalysis.

Imaging for select patients — Urologic imaging (renal sonogram and voiding cystourethrogram) is reserved for children who have significant daytime complaints, a history of UTI(s) not previously evaluated, and/or signs and symptoms of structural urologic abnormalities [3,39,95,96]. Ultrasonography may be helpful in determining postvoid residual volume and bladder wall thickness.

Indications for abdominal radiographs in children with constipation are discussed separately. Treatment of stool retention has been associated with resolved enuresis [97]. (See "Constipation in infants and children: Evaluation", section on 'Adjunctive testing for selected patients'.)

Neurologic imaging (usually magnetic resonance imaging of the spine) is indicated in children who are noted to have abnormalities of the lower lumbosacral spine (picture 1) or abnormalities on neurologic examination of the perineum and lower extremities [98]. (See "Closed spinal dysraphism: Clinical manifestations, diagnosis, and management", section on 'Clinical manifestations'.)

REFERRAL — Children who have clinical or radiographic findings suggestive of renal/urologic abnormality or bladder overactivity should be referred to a pediatric nephrologist/urologist for further evaluation. Such findings include [3]:

●Daytime incontinence, urgency, holding measures, increased (≥8 times/day) or decreased (≤3 times/day) voiding frequency (possible bladder dysfunction)

●Weak stream, use of abdominal pressure, continuous incontinence, micturition in more than one phase (possible neurogenic bladder or anatomic abnormalities)

●Proteinuria, nausea, weight loss, or fatigue (possible kidney disease)

●Excessive thirst, need for nighttime drinking (possible polydipsia or kidney disease)

Referral to an enuresis specialist (eg, developmental-behavioral pediatrician, pediatric urologist, pediatric nephrologist, child psychologist) also may be warranted for children who have nightly enuresis [3,99]. Nightly enuresis is associated with increased risk of persistence into adulthood [99], which may be ameliorated by early intervention and treatment.

Referral to a pediatric neurosurgeon may be warranted for children with clinical or radiographic findings suggestive of occult spinal dysraphism (eg, abnormalities of the lower lumbosacral spine (picture 1)).

Referral to a sleep specialist may be warranted for children with evidence of adenotonsillar hypertrophy or sleep disordered breathing. (See "Parasomnias of childhood, including sleepwalking", section on 'Sleep enuresis' and "Evaluation of suspected obstructive sleep apnea in children", section on 'Evaluation'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Enuresis in children".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient education" and the keyword[s] of interest.)

●Basics topic (see "Patient education: Bedwetting in children (The Basics)")

●Beyond the Basics topic (see "Patient education: Bedwetting in children (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Terminology – Enuresis refers to discrete episodes of urinary incontinence during sleep in children who are ≥5 years of age. Monosymptomatic enuresis refers to enuresis in children without any other lower urinary tract symptoms and without a history of bladder dysfunction. (See 'Terminology' above.)

●Epidemiology and natural history – Monosymptomatic nocturnal enuresis has a high rate of spontaneous resolution: The prevalence decreases from 15 percent among five-year-old children to 1 to 2 percent among those ≥15 years (figure 1). (See 'Epidemiology and natural history' above.)

●Pathogenesis – Monosymptomatic nocturnal enuresis may result from one or a combination of several related factors in a given child (eg, maturational delay, genetic factors, nocturnal polyuria, disturbed sleep, small bladder capacity, detrusor overactivity). (See 'Pathogenesis' above.)

●Evaluation – The evaluation of children with nocturnal enuresis should include a complete history (table 3), voiding diary (form 1), physical examination (table 4), and urinalysis. The main purpose of the evaluation is to determine whether the child has bladder dysfunction (also called complex or complicated enuresis) or enuresis as a manifestation of an underlying medical problem. (See 'Causes of nocturnal enuresis' above and 'Evaluation' above.)

●Indications for referral – Children who have clinical or radiographic findings suggestive of renal/urologic abnormality or bladder overactivity should be referred to a pediatric nephrologist/urologist for further evaluation. Referral to a pediatric neurosurgeon may be warranted for children with clinical (picture 1) or radiographic findings suggestive of spinal dysraphism. Referral to an enuresis specialist may be warranted for children who have nightly enuresis. (See 'Referral' above.)