Primer: Diagnosis and Management of Uncomplicated Daytime Wetting in Children

Vijaya M Vemulakonda; Eric A Jones

Disclosures

Nat Clin Pract Urol. 2006;3(10):551-559. 

In This Article

Classification of Pediatric Urinary Incontinence

Classification of pediatric urinary incontinence has been complicated by the lack of standardized definitions. In 1997, the International Children's Continence Society addressed this problem by the publication of a report that aimed to standardize and define lower urinary tract dysfunction in children. In this consensus report, urinary incontinence was defined as "the involuntary loss of urine, objectively demonstrable, and constituting a social or hygienic problem".[6] The International Children's Continence Society has recently released an updated report on the standardized terminology for lower urinary tract function in children and adolescents.[7] The remainder of this article adheres to these updated guidelines.

Childhood urinary incontinence can be caused by an underlying disease process (organic incontinence), or can have no underlying associated abnormality (functional incontinence) (Figure 1). In patients with organic urinary incontinence, an underlying anatomic or neurogenic abnormality is present. Structural urinary incontinence refers to developmental, iatrogenic, and traumatic anatomic abnormalities of the lower urinary tract that interfere with the urinary system's ability to store or evacuate urine. Included in this classification are etiologic factors such as the exstrophy-epispadias complex, ectopic ureter, and posterior urethral valves. Neuropathic urinary incontinence refers to abnormalities of bladder or urinary sphincter innervation, and can also be congenital or acquired. Common neuropathic causes of urinary incontinence include neurospinal dysraphism, sacral agenesis, spinal-cord injury, cerebral palsy, and tethered spinal cord.

The diagram shows the International Children's Continence Society classification for childhood urinary incontinence, and includes the most common causes of functional daytime incontinence. Abbreviation: OAB, overactive bladder.

In contrast to organic urinary incontinence, functional urinary incontinence refers to cases of urinary incontinence in which no structural or neurologic abnormality can be identified. This classification covers a heterogeneous group of disorders, including urge syndrome, dysfunctional voiding, enuresis, and vaginal voiding. The majority of cases of urinary incontinence in children are included in this category.

Detrusor overactivity (or the inability to maintain detrusor quiescence) is common during the transition from infantile voiding to an adult pattern of urinary control. Urge incontinence results from a recurrence or persistence of this transitional phase. Clinically, patients present with urinary frequency, the sudden imperative to void, and holding maneuvers such as flexing the pelvic-floor muscles, crossing the legs, and squatting on the heel (Vincent's curtsy). This symptom complex is caused by overactivity of the detrusor muscle, which results in sudden bladder contractions at volumes below the capacity that is expected for a particular age. Incontinence occurs in children who are unable to volitionally suppress these bladder contractions.[8]

Dysfunctional voiding includes several patterns of voiding with a common underlying feature: overactivity of the pelvic-floor musculature during micturition. Urge incontinence and dysfunctional voiding are thought to represent different time points during the natural history of a single disease process. Children with urgency symptoms learn to suppress detrusor contractions by volitionally contracting the external urethral sphincter and pelvic-floor muscles. Two forms of dysfunctional voiding have been described. Staccato voiding is characterized by bursts of pelvic floor activity during voiding, which leads to a rhythmic voiding pattern with incomplete bladder emptying and prolonged urinary flow. Fractionated voiding is characterized by small voided volumes with incomplete bladder emptying and an underactive detrusor muscle. Often, the detrusor contraction can be augmented by performing the Valsalva maneuver to increase urine flow rate and completeness of bladder emptying.[6] Long-term consequences of pelvic-floor overactivity include high-pressure voiding, urinary-tract infection, vesicoureteral reflux and, ultimately, decompensation of the detrusor muscle. Urinary incontinence can occur at any point along this spectrum and might be the result of detrusor instability, urinary-tract infection, or overflow incontinence.[8]

Previously termed 'lazy bladder syndrome', underactive bladder is characterized by infrequent voiding. Patients typically void only once or twice daily, and often do not void on waking. They are typically dry at night-time. Children have an increased bladder capacity and diminished sensation of bladder fullness. The syndrome is more common in girls than boys.[9]

The most severe form of dysfunctional voiding is non-neurogenic neurogenic bladder syndrome (Hinman-Allen syndrome). In this condition, children present with features of severe obstructive uropathy, including elevated postvoid residual (PVR) urine volume, a thickened, trabeculated bladder wall, recurrent urinary-tract infections, and acquired vesicoureteral reflux and hydronephrosis. Despite the severity of their symptoms, no underlying anatomic or neurologic etiology can be found in these children. This syndrome is thought to result from learned discordance between detrusor contraction and external urethral sphincter relaxation.[10]

Unlike other forms of functional incontinence, enuresis is characterized by a physiologically coordinated void that occurs at a socially unacceptable time. It typically occurs while asleep (nocturnal enuresis). This disorder is extremely common in young children, with a reported incidence of 15-20% in five-year-olds. It is characterized by spontaneous resolution, which occurs in 15% of affected children each year after the age of 5. Approximately 2% of 15-year-old children will continue to have nocturnal enuresis.[11]

A rare type of incontinence, giggle incontinence occurs during intense laughter. It is characterized by an abrupt, uncontrollable bladder contracture and is generally associated with complete bladder emptying. Affected individuals often modify their social interactions to avoid situations likely to induce laughter.

Functional urinary incontinence can also result from extraurethral causes. A common example is vaginal reflux. Vaginal reflux is a specific form of incontinence characterized by post-void dribbling. This condition is seen primarily in overweight girls who cannot adequately separate the labia during urination. Occasionally, vaginal reflux occurs in slender girls who adopt a hairpin posture while sitting on an adult toilet. Vaginal voiding is generally treated by modification of the voiding posture to prevent pooling of urine in the vagina during voiding. Overweight girls will respond to reverse toilet voiding. Slender girls should be encouraged to void with a pediatric toilet insert.

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