eMedicine Specialties > Urology > Neurogenic Bladder and Overactive Bladder

Overactive Bladder in Children

Author: Pamela I Ellsworth, MD, FACS, Associate Professor of Urology, Brown University; Consulting Staff, University Urological Associates
Coauthor(s): Katherine M Callaghan, University of Massachusetts Medical School
Contributor Information and Disclosures

Updated: Feb 5, 2008

Introduction

Background

Idiopathic overactive bladder (OAB) is a term that has been adopted by the International Continence Society (ICS) to describe the symptom complex of urinary urgency, which may or may not be associated with urgency urinary incontinence, urinary frequency, and nocturia in the absence of pathologic or metabolic factors that cause or mimic these symptoms.¹ In the pediatric literature, OAB is often referred to as -urge syndrome and is best characterized by frequent episodes of an urgent need to void, countered by contraction of the pelvic floor muscles and holding maneuvers such as squatting and the Vincent curtsy sign.

The cardinal symptom of OAB is urgency, which is defined as a sudden compelling desire to void that is often difficult to defer. Urgency must be differentiated from the urge to void, which is a normal sensation experienced by all individuals and may be intense when urine is held for a prolonged period. The definition of urinary frequency in a child is not well-established. However, many believe that a child who has a normal fluid intake and who voids more than 7 times per day has urinary frequency. The ICS defines nocturia as the need to wake at night one or more times to void.

Depending on fluid intake and urine production, children may experience more episodes of incontinence later in the day due to fatigue and an impaired ability to concentrate. In some cases, children with OAB remain dry during the day yet wet at night. However, such children experience daytime urgency and, often, daytime frequency.

Pathophysiology

The symptoms of OAB are believed to be caused by detrusor overactivity during the filling phase, causing urgency, as depicted in the image below. These detrusor contractions are countered by voluntary contraction of the pelvic floor muscles in an attempt to postpone voiding and to minimize wetting. The voiding phase is essentially normal but may be associated with a powerful detrusor contraction during voiding.
 

The natural history of OAB is not well-understood. Many believe that idiopathic OAB in children is the result of a maturation delay and that it resolves over time. This belief is in contrast to the theory behind OAB in adults, in whom the condition is believed to be chronic.

Frequency

United States

The prevalence of OAB in children is difficult to determine, as studies have focused primarily on daytime versus nighttime incontinence and have not attempted to differentiate the type of daytime incontinence. In a population survey of 1,192 individuals aged 1.5 to 27 years, diurnal accidents occurred in 13% of children aged 4 years, 7% of children aged 5 years, 10% of children aged 6 years, and 5% of children aged 7 years.²

International

Studies performed outside the United States have demonstrated that 2-4% of 7-year-old children have daytime or combined daytime and nighttime incontinence at least once per week and that it is more common in girls than in boys.³ In a population-based study of children aged 4-6 years in Australia, 19.2% had at least one daytime wetting episode in the preceding 6 months, with 16.5% having experienced more than one wetting episode and only 0.7% experiencing wetting on a daily basis.⁴ Up to 50.7% of children with daytime wetting have been noted to have urgency, with 79% wetting themselves at least once in a 10-day period.⁵

Mortality/Morbidity

Children with OAB have an increased risk of urinary tract infections (UTIs), which may be related to damage to the bladder mucosa during powerful detrusor contractions. In addition, frequent voluntary contractions of the pelvic floor muscles may also lead to postponement of defecation. Constipation and fecal soiling are often identified in children with OAB.

In addition, symptoms of pediatric OAB and urinary incontinence may lead to embarrassment in the child. The child may be inappropriately labeled as having a psychologic problem. Children with OAB may refrain from social activities, in fear of wetting and of letting others know how frequently they void. Difficulties may develop between the child and the child's peers, parents, or both.

Sex

Hellstrom et al (1990) assessed the prevalence of urinary incontinence in 7-year-old Swedish children.⁶ Diurnal incontinence was more common in girls (6.7%) than in boys (3.8%) . Wetting every week was reported in 3.1% of girls and in 2.1% of boys. Most children with diurnal incontinence had other symptoms. Urgency was reported in 4.7% of girls and in 1.3% of boys.

Age

Urge symptoms seem to peak in children aged 6-9 years and to diminish as they approach puberty, with an assumed spontaneous resolution rate for daytime wetting of 14% per year.^7,8

Clinical

History

The clinical presentation of overactive bladder (OAB) in children is similar to that in adults. The clinical features include urgency, urinary frequency, urinary urge incontinence, and nocturia or nocturnal enuresis.

• Children often exhibit various behaviors to prevent urinary leakage, including squatting behaviors and the Vincent curtsy sign.
• Children may have a history of recurrent UTIs and constipation.
• A careful voiding and bowel history, as well as a review of fluid intake (including type of fluid), is important to note.
• In girls, voiding habits should be reviewed to ensure proper positioning during voiding to eliminate vaginal reflux voiding as a source of incontinence.

Physical

Physical examination findings are usually normal in children who have idiopathic OAB.

• Children with urinary incontinence may have perineal excoriation.
• A focused neurologic examination should be performed to rule out an underlying neurologic etiology. The examination includes an assessment of perineal sensation, assessment of the perineal reflexes supplied by sacral segments S1-S4 (standing on toes, bulbocavernosus reflex), evaluation of anal sphincter tone, and evaluation of the buttocks, legs, and feet for signs of occult neurospinal dysraphisms of the lumbosacral area.
• The position and caliber of the urethral meatus should be inspected.
• The abdominal examination should include assessment for a distended bladder and a full sigmoid/descending colon suggestive of constipation.
• The sacrum should be palpated to ensure that it is present and the presacral area inspected for dimples, abnormal gluteal clefts, hairy patches, and other signs of possible neurologic lesions.

Causes

In children, OAB may arise from various etiologies, including neurogenic, anatomic, inflammatory, and idiopathic causes. Neurogenic etiologies include myelomeningocele, cerebral palsy, spinal cord injury, sacral agenesis, and imperforate anus. Twenty-two percent of children with a lumbosacral myelomeningocele have uninhibited bladder contractions.⁹ In children with cerebral palsy, an unstable bladder is the most common urologic anomaly.

The most common anatomic abnormality associated with OAB is posterior urethral valves; 24% of males with this condition have OAB.¹⁰ Inflammatory processes in the bladder wall (eg, UTIs) may irritate receptors in the submucosa and detrusor muscle layers and may lead to OAB symptoms. Idiopathic OAB is thought to be secondary to delayed maturation of the reticulospinal pathways and inhibitory centers in the midbrain and cerebral cortex.

• Search for CME/CE on This Topic »