Etiology and clinical features of bladder dysfunction in children

INTRODUCTION — Bladder dysfunction, also referred to as voiding dysfunction, is a general term to describe abnormalities in either 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), previously referred to as dysfunctional elimination, which involves abnormalities in both bladder and bowel emptying [2].

The etiology and clinical features of non-neurologic bladder dysfunction in children will be reviewed here. The evaluation of non-neurologic bladder dysfunction in children is discussed separately. The clinical features, evaluation, and management of children with bladder dysfunction due to myelomeningocele also are discussed separately. (See "Evaluation and diagnosis of bladder dysfunction in children" and "Management of bladder dysfunction in children" and "Myelomeningocele (spina bifida): Urinary tract complications".)

DEFINITIONS OF SYMPTOMS — We use the International Children's Continence Society (ICCS), a global multidisciplinary organization of clinicians involved in the care of children with lower urinary tract dysfunction, standardized definitions for bladder dysfunction symptoms [2,3]. The ICCS definitions apply only to children who are five or more years of age, unless specifically noted otherwise.

●Daytime frequency – Increased daytime frequency is defined as voiding eight or more times during waking hours, whereas decreased daytime frequency is defined as three or fewer voids. The term pollakiuria is also used to define abnormally frequent small voids in a previously toilet-trained child with no evidence of polyuria or urinary tract infection.

●Incontinence – Incontinence is defined as uncontrolled leakage of urine, which can be continuous or intermittent.

●Urgency – Urgency is defined as the sudden and unexpected experience of an immediate need to void.

●Nocturia – Nocturia is defined as awakening to void at night.

●Hesitancy – Hesitancy is defined as difficulty in the initiation of voiding or if a child must wait a considerable amount of time before voiding starts. This term can be applied to children who have achieved bladder control regardless of age.

●Straining – Straining is defined as the application of abdominal pressure (Valsalva maneuver) by the child to initiate and maintain voiding and may be a pertinent finding in all age groups.

●Weak stream – A weak stream is defined as the observed ejection of urine with a weak force and may be a pertinent finding in all age groups.

●Intermittent stream – Intermittency of voiding is defined as a voiding stream of urine that occurs in several discrete bursts rather than the normal continuous stream. It is a normal physiologic pattern in children three years of age or younger.

●Dysuria – Dysuria is defined as burning or discomfort during voiding.

●Holding maneuvers – Holding maneuvers are observed behavior used to either postpone voiding or suppress urgency. Common maneuvers include standing on tiptoe, forcefully crossing the legs, or squatting with a hand pressed into the perineum (picture 1) (Vincent's curtsy [4]). These may be observed in children who have achieved bladder control regardless of age.

●Postmicturition dribbling – Postmicturition dribbling describes involuntary urine leakage immediately after completion of voiding in children who have achieved bladder control regardless of age.

NORMAL VOIDING — The two functional roles of the bladder are storage and elimination of urine.

Normal development of bladder control — The normal development of bladder control evolves from involuntary bladder emptying (incontinence) during infancy to daytime urinary continence, which normally occurs by four years of age, and finally successful day and night continence generally achieved by five to seven years of age [5]. Urinary continence is generally achieved after successful daytime and nighttime bowel continence.

The development of normal voiding and urine storage consists of increasing bladder capacity, improved coordination of the bladder and urinary sphincter, and decreasing frequency of incontinence with age. Although strict definitions do not exist for defining normal voiding habits by age, normal voiding is typically considered a lack of dysfunctional voiding habits as described above and discussed elsewhere. (See "Evaluation and diagnosis of bladder dysfunction in children", section on 'When to suspect bladder dysfunction'.)

Bladder capacity — In clinical practice, the expected bladder capacity (EBC) is based upon the age of the patient and can be calculated as follows for children two to 16 years of age [6]:

Of note, 30 ml is equivalent to one ounce.

Infants and young children have increasing bladder capacity with age but minimal post-void residual urine [7-9]. We use the following values for bladder capacity (BC) and post-void residual (PVR) for infants and young children:

●Newborn up to 1 week of age – BC: 25 ± 10 cc and PVR: 1.4 ± 1.1 cc

●1 week to 3 months of age – BC: 53 ± 13 cc and PVR: 5.7 ± 4.5 cc

●3 to 12 months of age – BC: 70 ± 30 cc and PVR: 7.1 ± 6.3

●12 to 24 months of age – BC: 76 ± 31 cc and PVR: 6.6 ± 7 cc

●24 to 36 months of age – BC: 128 ± 72 cc and PVR: 3.3 ± 5.3 cc

Bladder control and urinary continence — Development of bladder control is a progressive maturation process whereby the child first becomes aware of bladder filling, subsequently develops the ability to suppress detrusor contractions, and finally learns to coordinate sphincter and detrusor function [5]. These skills usually are achieved, at least during the day, by approximately four years of age. Nighttime bladder control can be achieved months to years after daytime control, but is not considered abnormal until after five to seven years of age. As voluntary bladder control matures, bladder capacity also increases and voiding frequency decreases.

Urinary continence is dependent 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 1). The normal coordination of the central and peripheral nervous system network permits the filling of the bladder and urine storage at low pressure with high-outlet resistance and voiding with low-outlet resistance and sustained detrusor (bladder wall muscle) contraction.

●Filling phase – To eliminate bladder contraction during the filling phase, activation of the sympathetic nervous system beta receptors of the bladder fundus results in detrusor muscle relaxation. Activation of sympathetic alpha receptors at the bladder neck result in bladder neck contraction and increased bladder outlet resistance. Stimulation of the pudendal motor neurons contracts the external urinary sphincter closing the proximal urethra and ensuring continence 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 [10]. If the bladder stores urine at high pressures (>40 cm H₂O), kidney injury may occur [11].

●Voiding phase – 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 resulting in detrusor muscle contraction, and inhibition of the sympathetic nervous system through the hypogastric nerves, which relaxes the bladder neck. Input from the higher cerebral centers can modify the function of the pontine micturition center. The normal infant voids approximately 20 times per day, which results in small voided volumes and incomplete bladder emptying [12]. Infantile bladder function had been thought to be due to a primarily immature state of filling and emptying by spinal cord reflex without volitional cortical control. However, some element of cortical control in infants appears to be present as supported by the observation that infants void while awake or during arousal from sleep and never during the quiet sleep phase [13]. Thus, it is suggested that the development of voluntary urinary control is a learned modification of the already preexisting integrated network between the peripheral and central nervous system [13].

The timing of urinary continence during childhood varies. However, the vast majority of children (85 to 95 percent) are continent by 10 years of age based on large observational studies [14-16].

ETIOLOGY — Bladder dysfunction results from disruptions of the normal voiding process 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 [17].

●Neurogenic causes – Neurogenic causes of bladder dysfunction disrupt the innervation of the bladder or external sphincter. Neurogenic causes are due to either congenital anomalies, such as myelomeningocele, or trauma to the central nervous system (eg, spinal cord injury). Any child with a suspected neurologic abnormality should be evaluated for occult neurologic lesion. (See "Myelomeningocele (spina bifida): Urinary tract complications".)

●Anatomic causes – Children with an anatomic abnormality generally have a history of never gaining urinary control 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 there is obstruction of the bladder outlet (eg, posterior urethral valves). Vesicoureteral reflux (VUR) has also been identified as a risk factor for BBD. In a secondary multivariable analysis of data from the Randomized Intervention for Children with Vesicoureteral Reflux (RIVUR) and Careful Urinary Tract Infection Evaluation (CUTIE) trials identified female sex and dilating VUR at baseline as risk factors for developing BBD in 111 children during the study periods [18]. (See "Ectopic ureter" and 'Vesicoureteral reflux' below.)

●Functional causes – Functional refers to idiopathic bladder dysfunction with no known anatomic or neurologic cause. Proposed theories regarding the pathogenesis of functional bladder dysfunction include maturation delay, prolongation of infantile bladder behavior, or abnormal acquired toilet training habits [2,3,19,20].

DEFINITION OF BLADDER DYSFUNCTION DISORDERS — The International Children's Continence Society (ICCS) has developed standardized definitions of several bladder dysfunction conditions based upon symptom complex and urodynamic tests. The goal of the ICCS classification is to use a set of uniform definitions to avoid the widespread use of different definitions for the same conditions that leads to an inability to compare studies [2,3]. (See 'Definitions of symptoms' above.)

The ICCS classification defines pediatric urinary incontinence into two major categories [2,3]:

●Enuresis or 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 and are discussed in the next section.

DAYTIME URINARY INCONTINENCE

Overview — 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 [21].

The prevalence of daytime urinary incontinence, defined as a wetting accident at least once every two weeks, decreases with increasing age as follows [22]:

●Five to six-year-old children – 10 percent

●6 to 12-year-old children – 5 percent

●12 to 18-year-old children – 4 percent

In one 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 [23]. 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 a history of nocturnal enuresis, urinary tract infection, or encopresis.

Daytime urinary incontinence can cause major stress in school-age children [24,25] and negatively impact a child's self-esteem [26]. Thus, it is desirable to identify and treat children with daytime urinary incontinence as early as possible.

The following conditions and their underlying abnormalities of bladder function result in daytime urinary incontinence [2,3].

●Overactive bladder.

●Voiding postponement and underactive bladder.

●Dysfunctional voiding.

●Other conditions that result in daytime urinary incontinence include giggle incontinence, vaginal voiding, and primary bladder neck dysfunction.

It should be recognized that these groupings are not fully evidence based and did not include anatomical causes. The groupings are based upon the opinions of experts in the field of pediatric bladder dysfunction and there may be overlap between these conditions. 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 develop dysfunctional voiding. As new data emerge, future modifications of these conditions will be performed by the board of the ICCS [2,3].

The evaluation and diagnosis of these conditions are discussed separately. (See "Evaluation and diagnosis of bladder dysfunction in children".)

Overactive bladder — The overactive bladder is defined as abnormal bladder contraction during the filling phase and is detected by urodynamic evaluation. It is the second most common bladder dysfunction disorder following nocturnal enuresis [27].

The hallmark symptom of this disorder is urgency, and a clinical diagnosis can be made if urgency is present [2,3]. Incontinence and increased frequency are also common features of an overactive bladder. Holding maneuvers, such as Vincent's curtsy (squatting position with the legs crossed to prevent micturition or leaking), are often observed in affected children [4].

The prevalence of overactive bladder decreases with increasing age as illustrated in a study of the micturition habits of 1034 Swedish students evaluated twice, once when entering school and once during adolescence [28,29]. The following findings were noted:

●At seven years of age, 21 percent of females and 18 percent of males had moderate to severe urinary urgency. Daytime wetting occurred in 6 and 4 percent of females and males, respectively.

●At 17 years of age, 6 percent of females and 1 percent of males reported urgency, daytime incontinence, emptying difficulties, or enuresis.

Similar findings were reported from a cross-sectional survey of 19,240 Korean school children [30]. The overall incidence of overactive bladder defined as urgency with or without incontinence was 17 percent. The rate declined with increasing age, with the highest incidence in five-year-old children of 23 percent and the lowest in 13-year-old patients of 12 percent. Children with symptoms of overactive bladder compared with those without symptoms were more likely to have nocturnal enuresis, constipation, fecal incontinence, a history of urinary tract infection, delayed bladder control, and poor toilet facilities. (See 'Associated conditions' below.)

Voiding postponement and underactive bladder — Voiding postponement occurs in children who habitually postpone micturition, often in specific settings (eg, school). Resulting in a low frequency of voiding. These children commonly have behavioral issues or have a psychological comorbidity [2,3]. (See 'Associated conditions' below.)

Children with voiding postponement will utilize holding maneuvers to prevent voiding. These children generally have a low voiding frequency with long-time intervals between voids that result in increasing bladder capacity over time. With overdistension of the bladder, the detrusor muscle becomes overstretched and hypoactive leading to a weak or absent contraction referred to as an underactive bladder, which was formerly called "lazy bladder syndrome" or myogenic failure. Children with underactive bladder will use a Valsalva maneuver to increase abdominal pressure (ie, straining) to aid in bladder emptying. However, despite these efforts, large-volume post-void residuals with overflow incontinence are common in these children. Children with underactive bladder are at increased risk for urinary tract infection because of post-void residuals. (See 'Urinary tract infection' below.)

Underactive bladder is seen in approximately 7 percent of children with dysfunctional voiding [31]. 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 [2,3].Detrusor urethral sphincter dyssynergy is defined as dysfunctional voiding in children with a known neurologic lesion. Urinary incontinence due to spinal cord malformations (eg, myelomeningocele) or acquired spinal cord injuries is discussed separately. (See "Myelomeningocele (spina bifida): Urinary tract complications" and "Chronic complications of spinal cord injury and disease", section on 'Urinary complications'.)

Dysfunctional voiding in children without a known neurologic lesion is defined as non-neurogenic dysfunctional voiding. In these children, urodynamic studies demonstrate the abnormal contraction of the sphincter and/or pelvic floor musculature during voiding. Urinary flow is interrupted, producing a staccato pattern and a prolonged voiding time.

Non-neurogenic dysfunctional voiding, also referred to as Hinman-Allen syndrome, is the most severe form of dysfunctional voiding [32,33]. 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 [34,35]. In some cases, hydronephrosis may be observed when radiologic imaging is performed.

Patients with non-neurogenic bladder dysfunction are more likely to have constipation and, in more severe cases, encopresis and fecal soiling referred to as bowel and bladder dysfunction (previously called dysfunctional elimination syndrome). (See 'Bowel and bladder dysfunction' below and "Constipation in infants and children: Evaluation", section on 'Constipation and bladder dysfunction'.)

Children with this disorder are at increased risk for urinary tract infection (UTI) and vesicoureteral reflux (VUR). VUR is thought to be due to the increased intravesical pressure generated during voiding against the closed sphincter. In more severe cases, imaging studies demonstrate hydronephrosis due to severe VUR and trabeculated bladder due to bladder wall hypertrophy. Incomplete emptying is common and predisposes the child to a UTI. Kidney scarring has also been reported as a result of kidney injury in severe cases.

Other conditions — Other miscellaneous 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 [2,3]. 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 have persistent voiding symptoms when they are not laughing. It occurs almost exclusively in females and is characterized by large-volume voids.

Although the etiology of giggle incontinence is unclear, one theory suggests that this disorder is mediated by the central nervous system. The proposed mechanism is similar to that of cataplexy, in which an emotional event causes muscle hypotonia [31].

Treatment of this condition is not well studied. Some experts in the field advocate the use of anticholinergics based upon the assumption that incontinence is related to detrusor instability [36]. Small case series report that methylphenidate was effective in the prevention of these events suggesting a central nervous system etiology [37,38]. 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 [39].

Vaginal voiding — Vaginal voiding or vaginal reflux of urine is leakage of urine in toilet-trained females when they stand up after voiding and is a common cause of daytime urinary leakage in females [40]. This is due to urine being temporarily trapped in the vagina during micturition. It occurs particularly in females who urinate with their legs too closely approximated to permit free egress of urine. It is a pattern that can be seen during voiding cystourethrography with refluxing urine appearing within the vaginal vault during voiding.

Females with this condition may also have irritation of the labia and complain of dysuria as the urine passes over the irritated skin.

Treatment is based upon changing the voiding habits of the child by emphasizing wide abduction of the legs and a forward leaning posture to reduce the likelihood of vaginal reflux of urine. Other helpful tips include sitting backwards on the toilet so that the legs need to straddle the toilet or manually spreading the labia majora while voiding.

Primary neck bladder dysfunction — Primary neck bladder 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 [31]. Symptoms include hesitancy, frequency, urgency, weak urinary stream, pelvic pain or discomfort during voiding, sense of incomplete emptying, and occasional nocturnal enuresis [41].

Treatment of this condition is not well studied. Alpha-blockers have been reported to be effective and well-tolerated in the treatment of this disorder in children and adolescents [42,43].

ASSOCIATED CONDITIONS — The following comorbid conditions are associated with bladder dysfunction in children:

●Urinary tract infection

●Vesicoureteral reflux

●Bowel and bladder dysfunction

In addition, there appears to be an increased frequency of behavioral and neurodevelopment issues in children with bladder dysfunction.

Urinary tract infection — There is a clear association between bladder dysfunction and urinary tract infection (UTI) [44,45]. As a result, urine analysis should be performed in children presenting with bladder dysfunction to screen for UTIs. A urine culture should be performed based on urinalysis results. (See "Urinary tract infections in infants and children older than one month: Clinical features and diagnosis", section on 'Laboratory evaluation and diagnosis'.)

However, it is not known whether there is a causal relationship between UTI and bladder dysfunction. It has been theorized that a UTI may precipitate the development of bladder dysfunction [17]; however, data based upon case series support the supposition that bladder dysfunction predisposes children to recurrent UTI and kidney injury [44,46]. 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 neck bladder dysfunction with opening of the bladder neck during contraction.

Vesicoureteral reflux — Based upon several large case series, an association between vesicoureteral reflux (VUR) and bladder dysfunction has been demonstrated [18,44,45,47]. For children with VUR, when bladder dysfunction is present there is a higher incidence of UTI, longer time for VUR resolution, and increased failure rate of surgical correction [48-53]. A VCUG is not typically used to evaluate bladder dysfunction. However, it is obtained in children with UTI, or in males suspected of having posterior urethral valves (ie, thick-walled bladder and a weak urinary stream). (See "Urinary tract infections in infants older than one month and children less than two years: Acute management, imaging, and prognosis", section on 'Voiding cystourethrogram' and "Clinical presentation and diagnosis of posterior urethral valves", section on 'Diagnosis'.)

Treatment of bladder dysfunction, particularly overactive bladder, has been shown to improve spontaneous VUR resolution rate, suggesting an etiologic component for overactive bladder in the genesis of reflux [48,54,55]. (See "Management of vesicoureteral reflux", section on 'Bladder and bowel dysfunction'.)

Chronic kidney disease has been reported in a small case series of children with bladder dysfunction, recurrent UTIs, and VUR [56].

Bowel and bladder dysfunction — Anorectal and lower urinary tract function are interrelated. As a result, constipation is often associated with bladder dysfunction, with a reported frequency that ranges from 30 to 88 percent of children with bladder dysfunction [47,57-60]. This relationship between abnormal bowel and bladder function is referred to as the bowel and bladder dysfunction (BBD), which is also referred to as the dysfunctional elimination syndrome (DES).

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

●The first proposal suggests that rectal distention in the constipated child places direct pressure on the posterior bladder wall leading to detrusor overactivity or impaired bladder emptying [61,62].

●The second proposal assumes that 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.

●A third hypothesis suggests that 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, urinary tract infection, and/or VUR.

Association with UTI and VUR — BBD is a risk factor for urinary tract infection (UTI) and VUR [64,65]. The association between BBD and the combination of VUR and UTI was illustrated in the Randomized Intervention for Vesicoureteral Reflux (RIVUR) trial of 607 children with VUR [65]. In this study, bowel and bladder dysfunction was identified in 71 of 126 toilet-trained children (56 percent). The presence of bowel and bladder dysfunction at baseline increased the risk of recurrent febrile or symptomatic urinary tract (adjusted hazard ratio [HR]: 2.07, 95% CI 1.09-3.93).

In a retrospective study of 2759 children treated for VUR at a pediatric urology referral center, 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 — Bladder dysfunction may partly be a behavioral or learned process that perpetuates itself when not treated. Functional causes of bladder dysfunction are often believed to originate from behavioral issues arising from toilet training or limiting bathroom access.

In some cases, there may be a mild maturational delay of the central nervous system that disrupts the ability of these children to gain true voluntary bladder control by five years of age. Discouraging or limiting voiding in response to the urge to urinate in a child who has not developed complete cortical inhibition of voiding may alter normal bladder and sphincter function [66]. In part, this is due to a lack of awareness of teachers, school administrators, and parents/caregivers of the significance of daytime incontinence as a marker for bladder dysfunction [21,67]. Children may also avoid the school bathroom due to the lack of privacy or sanitation, resulting in voiding postponement. (See 'Voiding postponement and underactive bladder' above.)

In others, voluntary holding with postponement of voiding is acquired and may be reflective of ongoing behavioral issues [68], such as parent/caregiver and child conflict. One observational study based on answers to parental questionnaires found an association between BBD and unwanted pregnancy, daycare attendance, and/or school problems [69]. (See "Toilet training", section on 'Resistance or refusal'.)

Data from case series also support the association between attention deficit hyperactivity disorder (ADHD) and bladder dysfunction [70-72]. 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 [71].

RESOURCES — The International Children's Continence Society 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 generally achieved by five years of age. Urinary continence is dependent upon coordination of an interrelated network of autonomic and somatic nerves of the central and peripheral nervous systems (figure 1). Normal coordination results in bladder filling and urine storage at low pressure with high-outlet resistance and voiding with low-outlet resistance and sustained detrusor (bladder wall muscle) contraction. (See 'Normal voiding' above.)

●Types of bladder dysfunction and etiologies – Bladder dysfunction, defined as abnormalities in either 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 'Etiology' above and 'Definition of bladder dysfunction disorders' above and "Nocturnal enuresis in children: Etiology and evaluation".)

●Disorders of daytime incontinence – Daytime urinary incontinent disorders include the following:

•Overactive bladder defined as abnormal detrusor (bladder wall muscle) contractions during bladder filling. (See 'Overactive bladder' above.)

•Voiding postponement is the postponement of micturition resulting in a low frequency rate of voiding and increased bladder capacity. Over time, some children will develop an underactive bladder with weak or absent detrusor contraction. (See 'Voiding postponement and underactive bladder' above.)

•Dysfunctional voiding, defined as detrusor contractions against a closed external urinary sphincter during voiding, occurs in both 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.)

●Noctural 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 urinary tract infections, vesicoureteral reflux, and constipation. In addition, there appears to be an increased frequency of behavioral and neurodevelopment issues in children with bladder dysfunction. (See 'Associated conditions' above.)