Normal Voiding and Toilet Training

The fetus voids by reflex bladder contraction in concert with simultaneous contraction of the bladder and relaxation of the sphincter. Urine storage consists of sympathetic and pudendal nerve-mediated inhibition of detrusor contractile activity accompanied by closure of the bladder neck and proximal urethra with increased activity of the external sphincter. The infant has coordinated reflex voiding as often as 15-20 times/day. Over time, bladder capacity increases. In children up to the age of 14 yr, the mean bladder capacity in ounces is equal to the age (in yrs) plus 2.

At 2-4 yr, the child is developmentally ready to begin toilet training. To achieve conscious bladder control, several conditions must be present: awareness of bladder filling; cortical inhibition (suprapontine modulation) of reflex (unstable) bladder contractions; ability to consciously tighten the external sphincter to prevent incontinence; normal bladder growth; and motivation by the child to stay dry. The transitional phase of voiding refers to the period when children are acquiring bladder control. Girls typically acquire bladder control before boys, and bowel control typically is achieved before bladder control.

Diurnal Incontinence

Daytime incontinence not secondary to neurologic abnormalities is common in children (Chapter 21.3). At age 5 yr, 95% have been dry during the day at some time and 92% are dry. At 7 yr, 96% are dry, although 15% have significant urgency at times. At 12 yr, 99% are dry during the day. The most common cause of daytime incontinence is an overactive bladder. Table 537-1 lists the causes of diurnal incontinence in children.

Important points in the history include the pattern of incontinence, including the frequency, the volume of urine lost during incontinent episodes, whether the incontinence is associated with urgency or giggling, whether it occurs after voiding, and whether the incontinence is continuous. The frequency of voiding and whether there is nocturnal enuresis, a strong, continuous urinary stream, or sensation of incomplete bladder emptying should be assessed. A diary of when the child voids and whether the child was wet or dry is helpful. Other urologic problems such as urinary tract infections (UTIs), reflux, neurologic disorders, or a family history of duplication anomalies should be assessed. Bowel habits also should be evaluated, because incontinence is common in children with constipation and/or encopresis. Diurnal incontinence can occur in girls with a history of sexual abuse. Physical examination is directed at identifying signs of organic causes of incontinence: short stature, hypertension, enlarged kidneys and/or bladder, constipation, labial adhesion, ureteral ectopy, back or sacral anomalies (see Fig. 536-4), and neurologic abnormalities.

Assessment tools include urinalysis, with culture if indicated; bladder diary (recorded times and volumes voided, whether wet or dry); postvoid residual urine volume (generally obtained by bladder scan); Dysfunctional Voiding Symptom Score (Fig. 537-1); Bristol Stool Form Score (Fig. 537-2); and uroflow with or without EMG (noninvasive assessment of urinary flow pattern and measurement of external sphincter activity). Imaging is performed in children who have significant physical findings, a family history of urinary tract anomalies or UTIs, and those who do not respond to therapy appropriately. A renal ultrasonogram with or without a voiding cystourethrogram (VCUG) is indicated. Urodynamics should be performed if there is evidence of neurologic disease and may be helpful if empirical therapy is ineffective.

Figure 537-1 Dysfunctional Voiding Score questionnaire.

(From Farhat W, Bagli DJ, Capolicchio G, et al: The dysfunctional voiding scoring system: quantitative standardization of dysfunctional voiding symptoms in children, J Urol 164:1011–1015, 2000.)

Figure 537-2 Bristol Stool Chart for evaluating bowel function.

Overactive Bladder

Children with an overactive bladder typically exhibit urinary frequency, urgency, and urge incontinence. Often a girl will squat down on her foot to try to prevent incontinence (termed Vincent’s curtsy). The bladder in these children is functionally, but not anatomically, smaller than normal and exhibits strong uninhibited contractions. Approximately 25% of children with nocturnal enuresis also have symptoms of an overactive bladder. Many children indicate they do not feel the need to urinate, even just before they are incontinent. In girls, a history of recurrent UTI is common, but incontinence can persist long after infections are brought under control. It is not clear in these cases if the voiding dysfunction is a sequela of the UTIs or if the voiding dysfunction predisposes to recurrent UTIs. In girls, voiding cystourethrography often shows a dilated urethra (“spinning top deformity,” Fig. 537-3) and narrowed bladder neck with bladder wall hypertrophy. The urethral finding results from inadequate relaxation of the external urinary sphincter. Constipation is common and should be treated, particularly with any child with Bristol Stool Score 1 or 2.

Figure 537-3 Spinning top deformity. Voiding cystourethrogram demonstrating dilation of the urethra with distal urethral narrowing and contraction of the bladder neck.

The overactive bladder nearly always resolves, but the time to resolution is highly variable, sometimes not until the teenage years. Initial therapy is timed voiding, every 1.5-2.0 hr. Treatment of constipation and UTIs is important. Another treatment is biofeedback, in which children are taught pelvic floor exercises (Kegel exercises), because there is evidence that daily performance of these exercises can reduce or eliminate unstable bladder contractions. Biofeedback also may include periodic uroflow studies with sphincter electromyography to be certain that the pelvic floor relaxes during voiding, and assessment of postvoid residual urine volume by sonography. Anticholinergic therapy with oxybutynin chloride, hyoscyamine, or tolterodine reduces bladder overactivity and may help the child achieve dryness. Treatment with an α-adrenergic blocker such as terazosin or doxazosin can aid in bladder emptying by promoting bladder neck relaxation; α-adrenergic blockers also have mild anticholinergic properties. If pharmacologic therapy is successful, the dosage should be tapered periodically to determine its continued need. Children who do not respond to therapy should be evaluated urodynamically to rule out other possible forms of bladder or sphincter dysfunction. In refractory cases, sacral nerve stimulation (Interstim) is a surgical procedure that has shown promise.

Non-Neurogenic Neurogenic Bladder (Hinman Syndrome)

Hinman syndrome is a more serious but less common disorder involving failure of the external sphincter to relax during voiding in children without neurologic abnormalities. Children with this syndrome, also called detrusor-sphincter dyssynergia, typically exhibit a staccato stream, day and night wetting, recurrent UTIs, constipation, and encopresis. Evaluation of affected children often reveals vesicoureteral reflux, a trabeculated bladder, and a decreased urinary flow rate with an intermittent pattern (Fig. 537-4). In severe cases, hydronephrosis, renal insufficiency, and even end-stage renal disease can occur. The pathogenesis of this syndrome is thought to involve learning abnormal voiding habits during toilet training; the syndrome is rarely seen in infants. Urodynamic studies and magnetic resonance imaging of the spine are indicated to rule out a neurologic cause for the bladder dysfunction.

Figure 537-4 Voiding cystourethrogram demonstrating severe bladder trabeculation and vesicoureteral reflux in a 12-year-old boy with Hinman syndrome. The patient presented with day and night incontinence, had chronic renal failure, and underwent kidney transplantation.

The treatment usually is complex and can include anticholinergic and α-adrenergic blocker therapy, timed voiding, treatment of constipation, behavioral modification, and encouragement of relaxation during voiding. Biofeedback has been used successfully in older children to teach relaxation of the external sphincter. In some cases botulinum toxin (Botox) injection into the external sphincter can provide temporary sphincteric paralysis and thereby reduce outlet resistance. In severe cases, intermittent catheterization is necessary to ensure bladder emptying. In selected patients, external urinary diversion is necessary to protect the upper urinary tract. These children require long-term treatment and careful follow-up.

Infrequent Voiding

Infrequent voiding is a common disorder of micturition, usually associated with UTIs. Affected children, usually girls, void only twice a day rather than the normal 4 to 7 times. With bladder overdistention and prolonged retention of urine, bacterial growth can lead to recurrent UTIs. Some of these children are constipated. Some also have occasional episodes of incontinence due to overflow or urgency. The disorder is behavioral. If the child has UTIs, treatment includes antibacterial prophylaxis and encouragement of frequent voiding and complete emptying of the bladder by double voiding until a normal pattern of micturition is re-established.

Vaginal Voiding

In girls with vaginal voiding, incontinence typically occurs after urination after the girl stands up. Usually the volume of urine is 5-10 mL. One of the most common causes is labial adhesion (see Fig. 537-5). This lesion is seen in young girls and can be managed either by topical application of estrogen cream to the adhesion or lysis in the office. Some girls experience vaginal voiding because they do not separate their legs widely during urination. These girls either are overweight or do not pull their underwear down to their ankles when they urinate. Management involves encouraging the girl to separate the legs as widely as possible during urination. The most effective way to do this is to have the child sit backward on the toilet seat during micturition.

Figure 537-5 A, Labial adhesion. Note the inability to visualize the urethral meatus and vagina. B, Normal female external genitalia following lysis of labial adhesion.

Other Causes of Incontinence in Girls

Ureteral ectopia, usually associated with a duplicated collecting system in girls, refers to a ureter that drains outside the bladder, often into the vagina or distal urethra. It can produce urinary incontinence characterized by constant urinary dripping all day, even though the child voids regularly. Sometimes the urine production from the renal segment drained by the ectopic ureter is small, and urinary drainage is confused with watery vaginal discharge. Children with a history of vaginal discharge or incontinence and an abnormal voiding pattern require careful study. The ectopic orifice usually is difficult to find. On ultrasonography or intravenous urography, one may suspect duplication of the collecting system (Fig. 537-6), but the upper collecting system drained by the ectopic ureter usually has poor or delayed function. CT scanning of the kidneys or an MR urogram should demonstrate subtle duplication anomalies. Examination under anesthesia for an ectopic ureteral orifice in the vestibule or the vagina may be necessary (Fig. 537-7). The treatment in these cases is either partial nephrectomy, with removal of the upper pole segment of the duplicated kidney and its ureter down to the pelvic brim, or ipsilateral ureteroureterostomy, in which the upper pole ectopic ureter is anastomosed to the normally positioned lower pole ureter. These procedures often are performed by minimally invasive laparoscopy with or without robotic assistance.

Figure 537-6 Duplication of the right collecting system with ectopic ureter. Excretory urogram in a girl presenting with a normal voiding pattern and constant urinary dribbling. The left kidney is normal, and the right side, well visualized, is the lower collecting system of a duplicated kidney. On the upper pole opposite the first and second vertebral bodies, note the accumulation of contrast material corresponding with a poorly functioning upper pole drained by a ureter opening in the vestibule.

Figure 537-7 The photograph shows an ectopic ureter entering the vestibule next to the urethral meatus. The thin ureteral catheter with transverse marks has been introduced into this ectopic ureter. This girl had a normal voiding pattern and constant urinary dribbling.

Giggle incontinence typically affects girls 7-15 yr of age. The incontinence occurs suddenly during giggling, and the entire bladder volume is lost. The pathogenesis is thought to be sudden relaxation of the urinary sphincter. Anticholinergic medication and timed voiding occasionally are effective. The most effective treatment is low-dose methylphenidate.

Total incontinence in girls may be secondary to epispadias (Fig. 535-2). This condition, which affects only 1 of 480,000 females, is characterized by separation of the pubic symphysis, separation of the right and left sides of the clitoris, and a patulous urethra (Chapter 535). Treatment is bladder neck reconstruction or placement of an artificial urinary sphincter to repair the incompetent urethra.

A short, incompetent urethra may be associated with certain urogenital sinus malformations. The diagnosis of these malformations requires a high index of suspicion and a careful physical examination of all incontinent girls. In these cases, urethral and vaginal reconstruction often restores continence.

Voiding Disorders without Incontinence

Some children have abrupt onset of severe urinary frequency, voiding as often as every 10-15 min during the day, without dysuria, UTI, daytime incontinence, or nocturia. The most common age for these symptoms to occur is 4-6 yr, after the child is toilet trained, and the vast majority are boys. This condition is termed the daytime frequency syndrome of childhood or pollakiuria. The condition is functional; no anatomic problem is detected. Often the symptoms occur just before a child starts kindergarten or if the child is having emotional family stress-related problems. These children should be checked for UTIs, and the clinician should ascertain that the child is emptying the bladder satisfactorily. Occasionally, pinworms cause these symptoms. The condition is self-limited, and symptoms generally resolve within 2-3 mo. Anticholinergic therapy rarely is effective.

Some children have the dysuria-hematuria syndrome, in which the child has dysuria without UTI and microscopic or gross hematuria. This condition affects children who are toilet-trained and is often secondary to hypercalciuria. A 24-hr urine sample should be obtained and calcium and creatinine excretion assessed. A 24-hr calcium excretion of >4 mg/kg is abnormal and deserves treatment with thiazides, because some of these children are at risk for urolithiasis.

Nocturnal Enuresis

By 5 yr of age, 90-95% of children are nearly completely continent during the day, and 80-85% are continent at night. Nocturnal enuresis (Chapter 21.3) refers to the occurrence of involuntary voiding at night after 5 yr, the age when volitional control of micturition is expected. Enuresis may be primary (estimated 75-90% of children with enuresis; nocturnal urinary control never achieved) or secondary (10-25%; the child was dry at night for at least a few months and then enuresis developed). In addition, 75% of children with enuresis are wet only at night, and 25% are incontinent day and night. This distinction is important, because children with both forms are more likely to have an abnormality of the urinary tract.