Voiding Dysfunction

Updated: Sep 28, 2015
  • Author: Christopher S Cooper, MD, FACS, FAAP; Chief Editor: Marc Cendron, MD  more...
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Overview

Practice Essentials

As covered in this article, voiding dysfunction will refer to daytime voiding disorders in children who do not have neurologic, anatomic, obstructive, or infectious abnormalities of the urinary tract.

Causes of voiding dysfunction include the following:

  • Uninhibited detrusor contractions (overactive bladder [OAB])
  • Dysfunction of the pelvic floor musculature (dysfunctional voiding)
  • Decreased force of detrusor contractions (underactive bladder)

Signs and symptoms

Overactive bladder

A careful history usually reveals that the child has had ongoing urinary urgency. Children with OAB may display holding maneuvers, such as standing on tiptoes, crossing of the legs, or squatting with the heel pressed into the perineum.

Dysfunctional voiding

Dysfunctional voiding symptoms vary from mild daytime frequency and postvoid dribbling to daytime and nighttime wetting, urgency, urge incontinence, pelvic holding maneuvers, and urinary tract infections (UTIs). In the most severe form, children with dysfunctional voiding resemble those with neurogenic bladder or anatomic bladder outlet obstruction.

Giggle incontinence

Giggle incontinence is the occurrence of involuntary, complete bladder evacuation induced by laughter. It typically appears in children aged 5-7 years but may occur at older ages. The child’s voiding pattern is otherwise normal.

Underactive bladder

The condition is diagnosed if a child voids 3 or fewer times in 24 hours or if he or she does not void for 12 hours. These children may also use abdominal straining to void.

See Clinical Presentation for more detail.

Diagnosis

Urine analysis and culture

Urinalysis and quantitative urinary culture should be performed to evaluate for UTI. On urinalysis, the specific gravity (concentration) of the urine is noted, as is any evidence of underlying kidney problems based on the presence of hematuria, proteinuria, or glucosuria.

Imaging studies

  • Evaluation of patients with suspected dysfunctional voiding may include the following:
  • Voiding cystourethrography
  • Urinary tract ultrasonography
  • Magnetic resonance imaging (MRI) - Of the lumbosacral spine to rule out a neurologic etiology

Urodynamic testing

In select cases, urodynamic studies should be performed to detect uninhibited detrusor contractions, dysfunction of the pelvic floor muscles, or a hypotonic bladder.

See Workup for more detail.

Management

Treatments for voiding dysfunction include the following:

  • OAB - Voiding retraining program; anticholinergic medication if retraining is unsuccessful
  • Dysfunctional voiding - Voiding retraining program; suppressive antibacterial agents for patients prone to UTIs
  • Giggle incontinence - Possibly, if frequent, a trial of a timed voiding schedule with the addition of an anticholinergic agent; often resolves spontaneously with maturity
  • Underactive bladder - Children with large capacity, hypotonic urinary bladders who are unwilling or unable to comply with an improved voiding schedule can benefit from clean, intermittent catheterization
  • Constipation - There is a high prevalence of constipation in patients with voiding dysfunction, and treatment of constipation improves resolution of voiding dysfunction

See Treatment and Medication for more detail.

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Background

The types of voiding dysfunction covered in this article consist of daytime voiding disorders in children who do not have neurologic, anatomic, obstructive, or infectious abnormalities of the urinary tract. The disorders examined result from functional disturbance of the normal micturition cycle. Isolated nocturnal enuresis, which may be considered a form of voiding disorder, is not reviewed here. (See Pathophysiology and Etiology and Presentation.)

Causes of voiding dysfunction include the following, in isolation or in combination:

  • Uninhibited detrusor contractions ( overactive bladder [OAB])
  • Dysfunction of the pelvic floor musculature (dysfunctional voiding)
  • Decreased force of detrusor contractions (underactive bladder)

Voiding dysfunction is a common problem in children and accounts for as many as 40% of pediatric urology clinic visits. The challenge for the clinician is to differentiate between a pathologic pattern of urgency or incontinence due to an underlying urologic abnormality and benign conditions related to incomplete or abnormal toilet training. (See Epidemiology, Workup, Treatment, and Medication.)

For patient education information, see the Digestive Disorders Center, as well as Constipation in Children, Bladder Control Problems, and Bladder Control Medications.

Development of voiding control

Infants regularly void by detrusor (bladder muscle) contraction as often as hourly, with small voided volumes and incomplete bladder emptying. With increasing age, bladder capacity increases. The coordination between the bladder and sphincter system matures, leading to an improvement in bladder-emptying ability. [1]

Children aged 2-5 years have increased awareness of bladder fullness and develop the ability to void volitionally or to inhibit voiding until it is socially acceptable. During this period, acquisition of cortical control of micturition occurs. Many forms of voiding dysfunction can be thought of as a delay in the acquisition of daytime urinary control, which typically occurs by age 4 years.

Several studies have documented that more than 90% of children achieve full daytime control at age 4 years. [1] This finding suggests that most children are mature enough for independent volitional control of voiding at this age. Daytime wetting is therefore considered a problem in developmentally normal children aged 4 years or older who are wet several days each week, as well as in previously continent children who develop daytime wetting. (See Presentation.)

Micturition cycle

The micturition cycle involves the following two discrete processes:

  • Bladder filling and storage of urine
  • Bladder emptying with voiding

These functions are cyclic in nature.

Bladder filling and storage

During the filling phase of micturition, regulatory influence of the sympathetic nervous system allows the bladder to expand at low pressure. Urine storage is a coordinated response of the sympathetic-mediated inhibition of detrusor contractile activity. Normal filling requires the absence of involuntary bladder contractions. (The primary neurotransmitter for sympathetic activity is norepinephrine.)

During bladder filling, afferent impulses are transmitted to sensory neurons in the dorsal root ganglia of sacral spinal segments 2-4 and convey information to the brainstem. Nerve impulses from the brainstem during bladder filling inhibit parasympathetic outflow from the sacral spinal micturition center.

Voiding

Expulsion of urine is mediated by the parasympathetic nervous system (in which the primary neurotransmitter is acetylcholine). During the voiding phase, inhibition of the sacral parasympathetic outflow is removed, and detrusor contraction occurs. At the same time, somatic impulses traveling along the pudendal nerve relax the muscle of the external sphincter. The result is expulsion of urine with minimal outlet resistance.

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Pathophysiology and Etiology

Central nervous system (CNS) control over the lower urinary tract coordinates the micturition cycle and is initiated in the cerebral cortex. The neural pathway for voiding passes through the pons (Barrington nucleus) and into the spinal cord (Onuf nucleus). Normal development is characterized by increasing awareness of bladder distention and acquisition of the ability to inhibit voiding. Normal voiding frequency in children (after attainment of bladder control or age 5 years) is defined as four to seven voids per day.

Voiding symptoms (ie, urgency, frequency, and incontinence) reflect alterations in urinary bladder function. The pathogenesis of voiding disorders in the neurologically and anatomically intact child who has neither a urinary tract infection (UTI) nor local urethral irritation is best understood and managed when considered as a result of a functional disturbance of the normal voiding cycle (ie, bladder filling with urine storage, followed by bladder emptying with voiding).

Causes of voiding dysfunction include the following:

  • Uninhibited detrusor contractions ( OAB)
  • Dysfunction of the pelvic floor musculature (dysfunctional voiding)
  • Decreased force of detrusor contractions (underactive bladder)

A study by Oliver et al suggested that children with voiding dysfunction who are underweight, obese, or suffering from a psychiatric disorder or who have recently experienced a stressful event are likely to have a greater lower urinary tract symptom score (as measured through a symptom questionnaire) than other children with voiding dysfunction. In the report, which involved 358 patients aged 6-17 years, all of whom had nonneurogenic lower urinary tract dysfunction, the investigators found obesity, a recent life stressor, or a comorbid psychiatric disorder in 28.5%, 31.8%, and 22.9% of the patients, respectively. Younger age was also associated with a higher symptom score. [2]

Overactive bladder

OAB (also referred to as detrusor instability, hyperactive bladder syndrome, urge syndrome, and urge incontinence) is the result of overactive detrusor contractions during the filling phase of micturition. Detrusor overactivity is the most common voiding dysfunction in children.

Uninhibited detrusor contractions are thought to result from a lack of inhibitory cerebral control over detrusor contractions during bladder filling. Theories on the cause of OAB have included maturation delay, prolongation of infantile bladder behavior, or abnormality of acquired toilet training habits.

OAB can also occur in children with recurrent UTIs and is a risk factor for UTI. This voiding disorder may contribute to persistence of vesicoureteral reflux (VUR) and to the recurrence of VUR after ureteral reimplantation.

Dysfunctional voiding

Although the etiology is unknown, dysfunctional voiding is thought to reflect a deviation in the normal development of urinary control. As daytime urinary control is achieved, many children go through a transitional phase in which pelvic withholding maneuvers are used to prevent incontinence. Most children then develop a pattern of coordinated voiding that makes it unnecessary to contract the external sphincter to prevent incontinence.

However, some children who have a delay in establishing cerebral control over detrusor contractions continue to use pelvic-tightening maneuvers, and these maneuvers appear to become involuntary over time. Others have suggested that dysfunctional voiding can result from overtraining of the urinary bladder.

A report by Colaco et al indicated that an association exists between a child's temperament and the development of dysfunctional voiding. [3] In a study of 50 children, the investigators found that effortful control tended to be lower in boys with dysfunctional voiding than in those without it. In girls, there was a greater prevalence of urgency among those with dysfunctional voiding.

Underactive bladder

Urinary incontinence in underactive bladder syndrome is usually due to overflow from a large, hypotonic bladder. Patients with persistent voiding symptoms or UTIs should undergo urodynamic evaluation.

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Epidemiology

United States statistics

OAB is the most common lower urinary tract dysfunction in children; it appears to have a peak incidence between ages 5 and 7 years. [4] In a cross-sectional study, lower urinary tract dysfunction symptoms were detected in 21.8% of school-aged children. The most common urinary symptoms included holding maneuvers (19.1%) and urgency (13.7%). [5] Urge incontinence was reported in 7% of girls and in 3% of boys.

Another study, of 583 children aged 5-9 years, showed that urinary urgency and pelvic-tightening maneuvers to postpone voiding and prevent leakage were the most common voiding problems. [6]

International statistics

A large 2009 study from Australia addressed the frequency of voiding disorders in school-aged children. [7] This study of 2856 students reported that 17% of children had experienced daytime incontinence in the previous 6 months. Independent risk factors for daytime incontinence included nocturnal enuresis, female sex, history of UTI, and encopresis.

Age-related demographics

The prevalence of daytime wetting with a frequency of at least once every 2 weeks, as reported in different age groups, is as follows [8] :

  • Age 5-6 years - 10%
  • Age 6-12 years - 5%
  • Age 12-18 years - 4%

A functional voiding disorder in a neurologically and anatomically healthy child is not usually recognized before the acquisition of daytime urinary control.

Many children have a transient period of urinary urgency, occasionally with wetting accidents, when daytime continence is first being achieved. Most of these children develop normal urinary control in a relatively short period; however, some children may have persistence of urinary urgency and wetting.

Other children may have a normal voiding pattern until a UTI or an emotionally traumatic event triggers the onset of voiding symptoms.

Sex-related demographics

Studies on the prevalence of voiding disorders in school children indicate that daytime urinary incontinence is two to five times more common in girls. [7]

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Prognosis

The prognosis for complete or partial resolution of a functional voiding disorder is excellent for children with daytime urinary incontinence and detrusor instability.

Children with voiding dysfunction appear to be more likely to have adult OAB or voiding dysfunction. Several studies have reported that childhood incontinence in girls is a risk factor for urge symptoms and severe incontinence as adult women. [9, 10]

The prognosis is good for children with giggle incontinence (involuntary complete bladder evacuation induced by laughter), who tend to outgrow it during adolescence. A resolution rate of 89% was reported in children with this condition who were treated for detrusor instability. [11] The prognosis is also good for children with underactive bladder syndrome. The prognosis is guarded, however, for those few children with dysfunctional voiding whose condition does not respond to intervention.

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