Daytime Urinary Incontinence/Bladder and Bowel Dysfunction (in the Otherwise Healthy Child)
Angelique M. Champeau
A. In order to understand childhood urinary incontinence one must first understand the development of normal bladder control.
1. The neurophysiologic mechanism of normal urinary bladder is controlled by a complex integration of sympathetic, parasympathetic, and somatic innervation that involves the lower urinary tract, the micturition center in the sacral spinal cord, the midbrain, and higher cortical centers. Successful development of normal bladder function requires bladder storage of urine at low pressures with a closed sphincter and complete emptying of the bladder with a voluntary bladder contraction and an involuntary sphincteric relaxation.
2. Starting in the fetus, micturition occurs mainly by reflex voiding at frequent intervals without voluntary control. Bladder filling triggers afferent nerves, which through spinal reflexes cause both relaxation of the external urinary sphincter and detrusor contraction and result in complete emptying of the bladder.
3. By 6 months of age, the bladder capacity increases and the frequency of micturition decreases.
4. Between the ages of 1 and 2 years, conscious sensation develops.
5. By 2 to 3 years of age, the ability to initiate and inhibit voiding from the cerebral cortex develops. It is at this point that the lower urinary tract is most susceptible to abnormal learned cortical input (this may be as simple as a child who is told not to wet his or her pants).
6. A school-aged child will “normally” void 4 to 9 times per day.
7. Normal bladder capacity (BC) of a child is age related. Age in years + 2 = BC fluid ounces (Age in years + 2) × 30 BC in millimeters.
A. Urinary incontinence is defined as the involuntary leakage of urine in a child older than 5 years of age (the age at which a healthy child in our society should have acquired daytime continence). This particular age, however, depends on the culture of the family. Some cultures expect continence at much younger ages, often due to socioeconomic reasons (lack of availability of diapers and laundering facilities).
B. Causes of urinary incontinence in children can be thought of as acquired (dysfunctional, secondary) or nonacquired (familial, primary). Interestingly, the nonacquired causes of incontinence can lead to acquired (dysfunctional) problems.
A. Voiding Dysfunction
1. The term “voiding dysfunction” in childhood means a dysfunction or discoordination of the lower urinary tract without a recognized organic cause (neurologic disease, injury, or congenital malformation).
2. Voiding dysfunction, in general terms, is a discoordination between the bladder muscle and the external sphincter activity (Fig. 8-1) and can take many forms, including inability to voluntarily start or stop voiding, poor bladder emptying, increased bladder capacity, incontinence, and high pressures in the bladder.
3. Because older children can control their external sphincter more easily than their bladder muscle, it is easier for them to stop urination than to start it. The contraction of the external sphincter is subconscious and normal during bladder filling but is pathologic during bladder contraction. Although this may be a normal response to an inappropriate bladder contraction, if this continues on a regular basis it will lead to lower and, less often, upper urinary tract deterioration.
4. The contraction of the external sphincter at the time of a bladder contraction has been referred to as pelvic floor dysfunction (PFD). With voiding dysfunction, the PFD is a learned response.
B. Bowel Bladder Dysfunction (BBD)
1. Often, voiding dysfunction is associated with bowel dysfunction: constipation, stool incontinence, and/or recurrent urinary tract infections. When this occurs we classify this as bowel bladder dysfunction (BBD).
C. Nonneurogenic Neurogenic Bladder (NNNB or Hinman Syndrome)
1. Current thinking is that the nonneurogenic neurogenic bladder (Hinman syndrome) is the final clinical result of prolonged severe voiding dysfunction in children without an identifiable neurologic lesion. In this most severe form the abnormal learned voiding pattern can lead to residual urine, hydronephrosis, thickened and trabeculated bladders, vesicoureteral reflux, recurrent pyelonephritis, and ultimately to renal insufficiency. This is most often thought of as an acquired problem but has also been seen in small children prior to the accepted age of normal continence, so there may be a primary problem not yet identified. NNNB is rare.
D. Vesicovaginal Voiding
1. Vaginal voiding can be acquired or nonacquired. The acquired form is very common and often underdiagnosed or considered. Vaginal voiding is caused by children voiding with their legs in complete adduction and results in a portion of voided urine deflecting off the labia and refluxing and pooling in the vagina. This urine slowly dribbles out when the girl stands/walks after voiding. Sometimes the urine will only expel from the vagina when a child coughs or sneezes and will be misdiagnosed as “stress” incontinence (which is not children without neurologic or congenital abnormalities). This problem is more commonly found in obese children, but can be seen in any body habitus. Children with congenital anomalies such as common urogenital sinus anomalies (congenital adrenal hyperplasia) often have primary vaginal voiding.
E. Transient Wetting
1. Transient wetting can occur in association with a bladder infection, illness, or stress (birth or death of family member, sexual abuse).
F. Uninhibited Bladder or Overactive Bladder (OAB)
1. The uninhibited bladder can be primary or acquired. A primary uninhibited bladder is also known as a hyper bladder or spastic bladder and can be manifested by incontinence, urgency, and/or frequency. It occurs when the bladder involuntarily contracts (usually prior to age-appropriate capacity). The cause of this is unknown, but it tends to run in families and is often chronic. The hyper bladder will often become more hyper in response to stress or other triggers, not unlike asthma. The younger child may have incontinence at the time of this unexpected contraction while the older child may remain dry but void more frequently than normal. Often, in order to remain continent, children will contract their pelvic floor at the time of the contraction, which can lead to bowel bladder dysfunction thereby exacerbating the original problem. In its acquired form, a child with severe pelvic floor dysfunction can have such high pressures in the bladder that the bladder muscle hypertrophies, which subsequently may cause the bladder to exhibit uninhibited contractions, again exacerbating the original problem.
G. Voiding Frequency Disorders
1. Voiding frequency disorders come in two forms, either voiding too frequently or voiding too infrequently. These problems are often self-limited but can be quite frustrating for the child and family. Both may be associated with a psychosocial trigger, but not in all cases can one be identified.
2. Lazy bladder (infrequent voiders): The lazy bladder is a bladder with a large capacity and manifests itself with very infrequent voiding. The bladder develops poor contractility over time. Usually it is a result of prolonged voiding dysfunction but can also be seen in very young children who void with normal relaxation of the external sphincter albeit infrequent. Children may void as little as 1 to 3 times in 24 hours.
3. Benign urinary frequency: Children with severe urinary frequency syndrome experience an acute onset of extraordinary urinary frequency. They can feel the need to void as often as every 5 to 15 minutes during the day, but most will sleep throughout the night and are dry. Children will usually experience spontaneous remission within 3 months, although temporary recurrence is common.
H. Giggle Incontinence
A. Most otherwise healthy children can manage to stay dry during the day by the age of 4 years.
B. Of all children with a wetting problem, 10% will only have symptoms by day, 75% only by night, and 15% by both day and night.
C. Studies in children just starting school (6 to 7 years of age) have shown that 3.1% of girls and 2.1% of boys had an episode of daytime wetting at least once a week. Most of these children had urinary urgency (82% of girls and 74% of boys). For reasons that are not understood, there is also a difference in prevalence depending if the child lives in colder (2.5%) or hotter areas (1%).
D. Spontaneous Cure Rate
1. The spontaneous cure rate for daytime wetting is similar to that for nocturnal enuresis (about 14% of children will improve without treatment each year).
V. ASSOCIATED PROBLEMS
A. Bacteriuria/Urinary Tract Infection (see Chapter 6)
1. There is a strong association between bowel bladder dysfunction and bacteriuria. However, it is not known whether the bacteria cause the bladder dysfunction first or vice versa. Probably both are true and this often leads to a vicious cycle.