Etiology and clinical features of bladder dysfunction in children

INTRODUCTION — 

Bladder dysfunction, also known as voiding dysfunction, refers to abnormalities in the filling and/or emptying of the bladder. It is a common problem in children and constitutes up to 40 percent of pediatric urology clinic visits [1]. In some children, bladder dysfunction is a component of bowel and bladder dysfunction (BBD), which describes abnormalities in both bladder and bowel emptying and was previously referred to as dysfunctional elimination [2].

The etiology and clinical features of non-neurogenic bladder dysfunction in children will be reviewed here. Evaluation and management are discussed in separate topic reviews:

●(See "Evaluation and diagnosis of bladder dysfunction in children".)

●(See "Management of bladder dysfunction in children".)

Bladder dysfunction in myelomeningocele, a relatively common cause of neurogenic bladder dysfunction, is also discussed separately. (See "Myelomeningocele (spina bifida): Urinary tract complications".)

NORMAL VOIDING

Normal development of bladder control — Development of bladder control is a progressive maturation process from infancy through childhood. In infancy, voiding is a largely involuntary process, with small voids throughout the day and night, although some cortical control is probably present, suggested by the observation that infants void while awake or during arousal from sleep and never during the quiet sleep phase [3].

Daytime bladder control develops gradually during early childhood and is generally achieved by four years of age. The sequence of maturation starts with awareness of bladder filling, followed by the ability to postpone voiding by suppressing detrusor contractions, and finally voluntary initiation of voiding by coordinating sphincter relaxation and detrusor contraction [4]. As voluntary bladder control matures, bladder capacity also increases and voiding frequency decreases.

Nighttime bladder control can be achieved months to years after daytime control. Nighttime bladder control is achieved by age five years in approximately 85 percent of children and by 10 years in 95 percent [5-7]. Nighttime incontinence is approximately twice as common among males compared with females. (See "Nocturnal enuresis in children: Etiology and evaluation".)

Although strict definitions do not exist for defining normal voiding habits by age, normal voiding is typically considered a lack of dysfunctional voiding symptoms, as outlined in the table (table 1) and discussed in more detail elsewhere. (See "Evaluation and diagnosis of bladder dysfunction in children", section on 'When to suspect bladder dysfunction'.)

Normal bladder capacity — In clinical practice, the expected bladder capacity is based on the age of the patient and can be calculated as follows for children 2 to 16 years of age [8]:

Infants and young children have increasing bladder capacity with age and minimal postvoid residual urine [9-11]. Mean bladder capacity is approximately 25 mL in neonates, 70 mL between one and two years of age, and 130 mL at three years of age, while mean postvoid residual volumes are generally <10 mL throughout this age range [9,11].

Physiology of bladder control and urinary continence — The two functions of the bladder are storage and voiding of urine. Urinary continence depends on 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 1), and coordinate these actions:

●Filling/storage phase – The filling/storage phase is characterized by low bladder pressure and high outlet resistance. Activation of the sympathetic nervous system beta receptors of the bladder fundus results in detrusor muscle (bladder wall) relaxation. Meanwhile, activation of sympathetic alpha receptors at the bladder neck result in bladder neck contraction and increased bladder outlet resistance. Stimulation of the somatic pudendal motor neurons contracts the external urinary sphincter, closing the proximal urethra during the filling phase.

The normal bladder is highly compliant and allows the storage of urine at low pressures. One study reported that over 95 percent of children have bladder storage pressures of <30 cm H₂O at full capacity [12]. If the bladder stores urine at high pressures (>40 cm H₂O), kidney injury may occur [13].

●Voiding phase – The voiding phase is characterized by increased bladder pressure and low outlet resistance. As the bladder fills, stretching activates mechanoreceptors, which send an ascending signal through the spinal cord to the pontine micturition center in the brainstem. A descending signal from the pontine micturition through the spinal cord results in inhibition of the pudendal motor neurons (which relaxes the external urinary sphincter), stimulation of the parasympathetic outflow via the pelvic splanchnic nerves results in detrusor muscle contraction, and inhibition of the sympathetic nervous system through the hypogastric nerves relaxes the bladder neck. Input from the higher cerebral centers can modify the function of the pontine micturition center.

PATHOPHYSIOLOGY OF BLADDER DYSFUNCTION — 

Bladder dysfunction results from disruption of the normal voiding process and may be caused by any alteration of the innervation of the bladder or external sphincter, bladder compliance or volume capacity, detrusor muscle function, or structure of the bladder or bladder outlet. These include neurogenic, anatomic, or functional causes [14]. (See "Evaluation and diagnosis of bladder dysfunction in children", section on 'Evaluation of underlying etiology'.)

●Neurogenic causes – Neurogenic causes of bladder dysfunction disrupt the innervation of the bladder or external sphincter. Neurogenic causes are due to either congenital anomalies (eg, myelomeningocele) or trauma to the central nervous system (eg, spinal cord injury, neurologic disorders). A neurogenic cause is suggested by any abnormality detected on neurologic examination, cutaneous signs of occult spinal dysraphism or sacral agenesis, or history of perinatal/neonatal injury. These children should be evaluated for occult neurologic lesions. (See "Closed spinal dysraphism: Clinical manifestations, diagnosis, and management" and "Myelomeningocele (spina bifida): Urinary tract complications".)

●Anatomic causes – Children with an anatomic abnormality generally have a history of never gaining urinary control. This is because the anatomic defect either bypasses the bladder outlet (such as ectopic ureter with insertion distal to the bladder neck (figure 2 and figure 3)) or because there is obstruction of the bladder outlet (eg, posterior urethral valves) or an incompetent bladder outlet (eg, ureterocele, bladder exstrophy). (See "Ectopic ureter".)

●Functional causes – Functional refers to idiopathic bladder dysfunction with no known neurogenic or anatomic cause. Proposed theories regarding the pathogenesis of functional bladder dysfunction include maturation delay, prolongation of infantile bladder behavior, or abnormal acquired toilet training habits [2,15-17].

DEFINITIONS — 

We use the definitions from the International Children's Continence Society (ICCS), a global multidisciplinary organization of clinicians involved in the care of children with lower urinary tract dysfunction [2,15]. The ICCS developed these classifications and definitions to facilitate comparisons between studies [2,15].

Categories of bladder dysfunction disorders — The ICCS classification defines pediatric urinary incontinence into two major categories (table 2) [2,15]:

●Enuresis (intermittent nighttime incontinence) – Monosymptomatic nocturnal enuresis accounts for 80 percent of children with enuresis and is discussed in detail separately. (See "Nocturnal enuresis in children: Etiology and evaluation" and "Nocturnal enuresis in children: Management".)

●Daytime urinary incontinence disorders – These disorders encompass a variety of conditions that are generally applied to children at least five years of age with constant or daytime intermittent urinary leakage. The main categories are overactive bladder, voiding postponement, underactive bladder, and dysfunctional voiding. (See 'Daytime urinary incontinence' below.)

Bladder dysfunction symptoms — The ICCS defines bladder dysfunction symptoms, as outlined in the table (table 1); these definitions apply only to children who are five or more years of age, unless specifically noted otherwise [2].

DAYTIME URINARY INCONTINENCE — 

The following conditions and their underlying abnormalities of bladder function can result in daytime urinary incontinence [2,15]:

●Overactive bladder

●Voiding postponement and underactive bladder

●Dysfunctional voiding

●Other conditions – Including giggle incontinence, vaginal voiding, and primary bladder neck dysfunction

These groupings are based on the opinions of experts in the field of pediatric bladder dysfunction, and there may be overlap between these conditions [2,15]. In addition, changes in symptoms can evolve over time, so that a single child may have components of different conditions. As an example, a child may start with an overactive bladder with urge incontinence and later develop dysfunctional voiding.

The epidemiology of daytime urinary incontinence and clinical characteristics of these conditions are outlined below. The evaluation and diagnosis of these conditions are discussed separately. (See "Evaluation and diagnosis of bladder dysfunction in children".)

Epidemiology — Up to 20 percent of four- to six-year-old children experience occasional daytime wetting, and 3 percent will have wetting accidents two or more times per week [18].

The prevalence of daytime urinary incontinence, defined as a wetting accident at least once every two weeks, decreases with increasing age, as follows [19]:

●5 to 6 years – 10 percent

●6 to 12 years – 5 percent

●12 to 18 years – 4 percent

In a survey of primary school children in Australia with a mean age of 7.3 years and a response rate of 35 percent, 17 percent of reporting parents noted an episode of urinary incontinence [20]. The urinary incontinence was described as being very mild (urine spots on underwear) in 64 percent, mild (damp underclothes and pants) in 15 percent, moderate (noticeable seepage on outer clothing) in 12 percent, and severe (wet puddle on floor or seat) in 10 percent of cases. Risk factors for urinary incontinence included female sex and history of nocturnal enuresis, urinary tract infection (UTI), or fecal incontinence.

Daytime urinary incontinence can cause major stress in school-age children [21,22] and negatively impact a child's self-esteem [23]. Thus, it is desirable to identify and treat children with daytime urinary incontinence as early as possible.

Overactive bladder — Overactive bladder is the second most common bladder dysfunction disorder following nocturnal enuresis [24]. The hallmark symptom is urgency, and a clinical diagnosis can be made if urgency is present [2,15]. Other common clinical features are incontinence, increased frequency, and holding maneuvers such as Vincent's curtsy (squatting position with the legs crossed to prevent micturition or leaking) (picture 1) [25]. If urodynamic evaluation is performed, the diagnostic feature of overactive bladder is abnormal detrusor contraction during the filling phase.

The prevalence of overactive bladder decreases with increasing age, as illustrated in a study of the voiding habits of 1034 Swedish students [26,27]. At seven years of age, moderate to severe urgency was reported by 21 percent of females and 18 percent of males and daytime wetting occurred in 6 percent of females and 4 percent of males. At 17 years of age, symptoms of urgency, daytime incontinence, emptying difficulties, or enuresis were reported by 6 percent of females and 1 percent of males.

Similar findings were reported from a cross-sectional survey of 19,240 Korean schoolchildren [28]. The overall incidence of overactive bladder, defined as urgency with or without incontinence, was 17 percent. The rate declined with increasing age, with an incidence of 23 percent in five-year-old children, declining to 12 percent by 13 years of age. Children with symptoms of overactive bladder compared with those without symptoms were more likely to have nocturnal enuresis, constipation, fecal incontinence, history of UTI, delayed bladder control, and poor toilet facilities. (See 'Associated conditions' below.)

Voiding postponement and underactive bladder — Some children habitually postpone voiding, often in specific settings (eg, school). These children commonly have behavioral issues or have a psychological comorbidity [2,15] (see 'Behavioral and neurodevelopmental issues' below). They may utilize holding maneuvers to prevent voiding (picture 1). These children generally have a low voiding frequency, with long time intervals between voids, which may result in increasing bladder capacity over time.

Some children with voiding postponement develop underactive bladder (formerly called "lazy bladder syndrome"), characterized by poor or absent bladder contraction. It is caused by repeated overdistension of the bladder, which impairs detrusor muscle function ("myogenic failure"). Children with underactive bladder may use a Valsalva maneuver to increase abdominal pressure (ie, straining) to aid in bladder emptying. However, despite these efforts, large postvoid residuals with overflow incontinence are common in these children. Children with underactive bladder are at increased risk for UTI because of postvoid residuals. (See "Evaluation and diagnosis of bladder dysfunction in children" and 'Urinary tract infection (UTI)' below.)

Underactive bladder is seen in approximately 7 percent of children with dysfunctional voiding [29]. In this group of children, there is a predominance in females, with a female-to-male ratio of 5 to 1.

Dysfunctional voiding — Dysfunctional voiding (defined as detrusor contractions during voiding against a closed external urinary sphincter) is caused by an inability to relax the urethral sphincter and/or pelvic floor musculature during voiding [2,15].

Dysfunctional voiding can be neurogenic or nonneurogenic:

●Neurogenic – Dysfunctional voiding in children with a known neurologic lesion (eg, myelomeningocele, spinal cord malformation) is caused by detrusor urethral sphincter dyssynergy. Urinary incontinence in these conditions is discussed separately. (See "Myelomeningocele (spina bifida): Urinary tract complications" and "Chronic complications of spinal cord injury and disease", section on 'Urinary complications'.)

●Non-neurogenic – Dysfunctional voiding in children without a known neurologic lesion is characterized by abnormal contraction of the sphincter and/or pelvic floor musculature during voiding on urodynamic studies. Urinary flow is interrupted, producing a staccato pattern and a prolonged voiding time.

Patients with dysfunctional voiding often have constipation and, in more severe cases, encopresis and fecal soiling, referred to as bowel and bladder dysfunction (BBD). (See 'Bowel and bladder dysfunction (BBD)' below and "Constipation in infants and children: Evaluation", section on 'Constipation and bladder dysfunction'.)

Children with dysfunctional voiding are at increased risk for UTI and vesicoureteral reflux (VUR). VUR is thought to be due to the increased intravesical pressure generated during voiding against the closed sphincter. Incomplete bladder emptying is common and predisposes the child to a UTI.

Severe non-neurogenic dysfunctional voiding may lead to hydronephrosis and kidney injury and is also referred to as Hinman-Allen syndrome [30,31]. The contraction of the sphincter during voiding and overactivity of the detrusor muscle can lead to high voiding pressure, bladder decompensation, and a predisposition for infection and kidney damage [32,33]. Imaging studies may demonstrate hydronephrosis due to severe VUR and trabeculated bladder due to bladder wall hypertrophy.

Other conditions — Other disorders that result in daytime urinary incontinence include giggle incontinence, vaginal voiding, and primary bladder neck dysfunction:

Giggle incontinence — Giggle incontinence, a rare syndrome, refers to urine leakage that occurs only with laughter [2,15]. Children with giggle incontinence have normal bladder function when the child is not laughing and should be differentiated from urinary leakage with laughter in children who also have voiding symptoms when they are not laughing. Giggle incontinence occurs almost exclusively in females and is characterized by large-volume voids. Unlike stress incontinence, where urinary leakage is from increased abdominal pressure on the bladder overcoming the sphincter resistance, giggle incontinence results in a bladder contraction and coordinated sphincter relaxation with complete emptying of the bladder.

Although the etiology of giggle incontinence is unclear, one theory suggests that this disorder is mediated by the central nervous system.

Treatment of this condition is not well studied. Some experts advocate the use of anticholinergic medications (oxybutynin), in combination with timed voiding, based on the assumption that incontinence is related to detrusor instability [34]. Alternatively, small case series report that methylphenidate was effective in the prevention of these events, suggesting a central nervous system etiology [35-37]. In one small case series, biofeedback to teach the patient to contract the external sphincter was effective in nine patients with giggle incontinence either refractory to medications or whose parents/caregivers refused pharmacotherapy [38].

Vaginal reflux — Vaginal reflux (or "vaginal voiding") is a common cause of daytime urinary leakage in females [39]. It is characterized by leakage of urine in toilet-trained females when they stand up after voiding and is due to urine being temporarily trapped in the vagina during voiding. It occurs particularly in females who urinate with their legs close together, which results in urine refluxing into the vagina. Affected children may also have irritation of the labia and complain of dysuria as the urine passes over the irritated skin.

The diagnosis usually can be made based on the clinical symptoms and does not require imaging. However, if a voiding cystourethrogram is performed, it will demonstrate reflux of urine into the vaginal vault during voiding.

Vaginal reflux is treated by teaching the child to void with their legs spread apart and a forward leaning posture to reduce the likelihood of vaginal reflux of urine. Other approaches are to have the child sit backward on the toilet so that the legs need to straddle the toilet or to manually spread the labia majora while voiding.

Primary bladder neck dysfunction — Primary bladder neck dysfunction is defined as delayed or incomplete opening of the bladder neck during voiding in patients with normally functioning sphincter and pelvic floor muscles. It may be underdiagnosed in children and, in a pediatric urologic center, it is reported to represent up to 15 percent of children with persistent voiding symptoms despite conventional treatment [29]. Symptoms include hesitancy, frequency, urgency, weak urinary stream, pelvic pain or discomfort during voiding, sense of incomplete emptying, and occasional nocturnal enuresis [40].

Treatment of this condition is not well studied. Alpha-adrenergic blockers have been reported to be effective and well tolerated in the treatment of this disorder in children and adolescents [41,42].

ASSOCIATED CONDITIONS — 

The following comorbid conditions are associated with bladder dysfunction in children.

Urinary tract infection (UTI) — Bladder dysfunction is associated with UTI [43,44]. As a result, urine analysis should be performed in children presenting with symptoms of bladder dysfunction to screen for UTIs. If the urinalysis result suggests infection, a urine culture should be performed. (See "Urinary tract infections in infants older than one month and children younger than two years: Clinical features and diagnosis", section on 'Laboratory evaluation and diagnosis'.)

The likely mechanism for the association is that bladder dysfunction predisposes children to UTIs, which, in turn, can lead to kidney injury [43,45]. In particular, the risk of bladder colonization and UTI is increased in children with incomplete bladder emptying due to dysfunctional voiding or underactive bladder or in those with primary bladder neck dysfunction with incomplete relaxation of the bladder neck during bladder contraction.

Vesicoureteral reflux (VUR) — Several large case series have demonstrated an association between bladder dysfunction and VUR [43,44,46,47]. The likely mechanism is that elevated storage and/or voiding pressures associated with bladder dysfunction might overcome the normal resistance to urine backflow at the ureterovesical junction, leading to VUR. As an example, in two large trials involving children with VUR, one-third of the participants (111/318) developed bowel and bladder dysfunction (BBD) during the two-year study period; female sex and dilating VUR at baseline were the primary risk factors for developing BBD [47]. Moreover, treatment of bladder dysfunction, particularly overactive bladder, has been shown to increase the likelihood of spontaneous VUR resolution, suggesting an etiologic component for bladder dysfunction in the genesis of reflux [48-50]. (See "Management of vesicoureteral reflux", section on 'Bladder and bowel dysfunction'.)

Among children with bladder dysfunction, those with VUR also have higher risk of complications, including UTI, longer time for VUR resolution, and increased failure rate of surgical correction of VUR [48,51-55]. Chronic kidney disease has been reported in a small case series of children with bladder dysfunction, recurrent UTIs, and VUR [56]. Hence, a voiding cystourethrogram should be performed to evaluate for VUR in children with bladder dysfunction and risk factors for VUR, including UTIs or hydronephrosis, or males suspected of having posterior urethral valves or urethral stricture (ie, thick-walled bladder noted on ultrasound and a weak urinary stream). (See "Urinary tract infections in infants older than one month and children younger than two years: Acute management, imaging, and prognosis", section on 'Voiding cystourethrogram' and "Clinical presentation and diagnosis of posterior urethral valves", section on 'Diagnosis'.)

Bowel and bladder dysfunction (BBD) — BBD, also known as dysfunctional elimination syndrome, refers to the combination of bladder dysfunction and abnormal bowel function often manifested as constipation. Indeed, 30 to 88 percent of children with bladder dysfunction have constipation [46,57-60].

●Proposed mechanisms – Although the underlying pathophysiology of the combined dysfunction is not fully understood, the following theories have been proposed [57]:

•Rectal distention in the constipated child places direct pressure on the posterior bladder wall, leading to detrusor overactivity or impaired bladder emptying [61,62].

•External urethral and anal sphincter neural input is a single functional unit. Prolonged external anal sphincter contraction in the presence of a large amount of stool in the rectum leads to inappropriate pelvic floor muscle contraction and secondary detrusor-urinary sphincter dyssynergy [63]. Increased parasympathetic activity may also be present as a result of the colonic and rectal distention, which leads to detrusor contraction.

•Prolonged external anal sphincter constriction in the presence of a large amount of stool leads to inappropriate contractility of pelvic floor muscle, resulting in concomitant urethral sphincter nonrelaxation. This causes detrusor-sphincter dyscoordination, which may lead to subsequent bladder overactivity, urinary incontinence, UTI, and/or VUR.

●Association with VUR and UTI – BBD is a risk factor for VUR and UTI [64,65]. The association between BBD and the combination of VUR and UTI was illustrated in a cohort of 500 children who presented with VUR and/or UTI, in which BBD was identified in 71 of 126 toilet-trained children (56 percent) [65]. The presence of BBD at baseline increased the risk of recurrent febrile or symptomatic UTI (adjusted hazard ratio 2.07, 95% CI 1.09-3.93) during follow-up.

The association is further supported by a retrospective study of 2759 children treated for VUR at a pediatric urology referral center, in which 36 percent of females and 21 percent of males with unilateral VUR had BBD [64]. Multivariate analysis demonstrated that BBD was not independently associated with either UTI or VUR alone but was strongly associated with the combination of the two. (See "Constipation in infants and children: Evaluation".)

Behavioral and neurodevelopmental issues — In some cases, behavioral and neurodevelopmental problems may contribute to the development and/or persistence of bladder dysfunction, including:

●Limited bathroom access – Some children may have a mild maturational delay of the central nervous system that disrupts their ability to gain full voluntary bladder control by five years of age. For these children, efforts to hold urine despite their immature cortical processes may promote bladder and sphincter dysfunction [66]. In other children without maturational delay, chronic restriction of bathroom access may result in pathogenic changes to their bladder function. Hence, it is important to educate caregivers and teachers regarding the importance of providing free access to the bathroom and that some children may require more frequent voiding and should be allowed and encouraged to use the bathroom frequently [18,67].

●Voluntary withholding – Similarly, some children habitually postpone voiding to avoid the school bathroom due to lack of privacy, sanitation, or other concerns. In these cases, understanding and addressing the voluntary withholding is an important step in managing the bladder dysfunction.

●Toilet training – Behavioral issues arising from toilet training sometimes result in withholding due to habitual reluctance to use the toilet, fears or anxieties, and/or power struggles with the parent/caregiver. (See "Toilet training", section on 'Problems and setbacks'.)

●Neurodevelopmental issues – Children with attention deficit hyperactivity disorder (ADHD) are also prone to bladder dysfunction [68-70]. In one study, children with ADHD were more likely to report symptoms of incontinence, urgency, infrequent voiding, nocturnal enuresis, and dysuria than those without ADHD [69].

●Other – Broader psychosocial or behavioral issues, such as conflict between the child and their parent/caregiver, sometimes contribute to bladder dysfunction [71]. An observational study based on parental questionnaires found an association between BBD and unwanted pregnancy, daycare attendance, and/or school problems [72].

In each of these scenarios, addressing the behavioral issues is an important focus for management of the bladder dysfunction.(See "Toilet training", section on 'Resistance or refusal' and "Management of bladder dysfunction in children", section on 'Voiding behavior modification'.)

RESOURCES — 

The International Children's Continence Society (ICCS) provides guidelines for the evaluation and treatment of bladder dysfunction, as well as information for the general public.

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: Urinary incontinence 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 e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Daytime wetting in children (The Basics)" and "Patient education: Vesicoureteral reflux in children (The Basics)")

SUMMARY

●Normal bladder function – Bladder function normally evolves from involuntary bladder emptying (urinary incontinence) during infancy to voluntary-control urinary continence, which is generally achieved by five years of age. Urinary continence depends on coordination of an interrelated network of autonomic and somatic nerves of the central and peripheral nervous systems (figure 1). (See 'Normal voiding' above.)

●Types of bladder dysfunction and etiologies – Bladder dysfunction, defined as abnormalities in filling and/or emptying the bladder, is a common problem in children that may result from neurogenic, anatomic, or functional disruptions of the normal voiding process. Bladder dysfunction is divided in two major categories: continuous or daytime urinary incontinent disorders, and nocturnal enuresis or nighttime incontinence. (See 'Pathophysiology of bladder dysfunction' above and 'Categories of bladder dysfunction disorders' above.)

●Disorders of daytime incontinence – Symptoms of bladder dysfunction in children include urinary incontinence, urgency, abnormal voiding frequency, and urinary tract infections (UTIs) (table 2). Daytime urinary incontinent disorders include (table 1):

•Overactive bladder – Characterized by abnormal detrusor (bladder wall muscle) contractions during bladder filling or storing, causing urgency, frequent voiding, and/or incontinence. (See 'Overactive bladder' above.)

•Voiding postponement – Characterized by postponement of voiding (micturition) and increased bladder capacity. Over time, this can cause an underactive bladder with weak or absent detrusor contraction and incomplete bladder emptying. (See 'Voiding postponement and underactive bladder' above.)

•Dysfunctional voiding – Characterized by detrusor (bladder wall muscle) contractions against a closed external urinary sphincter during voiding. This can occur in children with a known neurologic lesion (ie, detrusor urethral sphincter dyssynergy) or without a known neurologic lesion (ie, non-neurogenic dysfunctional voiding). (See 'Dysfunctional voiding' above.)

•Other daytime urinary incontinent disorders include giggle incontinence, vaginal voiding, and primary bladder neck dysfunction. (See 'Other conditions' above.)

●Nocturnal incontinence – Nocturnal enuresis is discussed in detail separately. (See "Nocturnal enuresis in children: Etiology and evaluation" and "Nocturnal enuresis in children: Management".)

●Comorbid conditions – Comorbid conditions associated with bladder dysfunction include UTI, vesicoureteral reflux (VUR), and constipation. In addition, behavioral and neurodevelopmental problems and/or limited bathroom access may contribute to the development and/or persistence of bladder dysfunction. (See 'Associated conditions' above.)