Approach Considerations
Urinalysis is the most important screening test in a child with enuresis. Blood tests are not needed. No imaging is needed if primary enuresis (PE) is suspected; however, radiologic evaluation might be warranted if other conditions are being considered.
Laboratory Studies
Children with cystitis usually have white blood cells (WBCs) or bacteria evident in the microscopic urinalysis. Children with overactive bladder or dysfunctional voiding, urethral obstruction, neurogenic bladder, ectopic ureter, or diabetes mellitus are predisposed to cystitis. If the urinalysis findings suggest cystitis, a clean-catch urine specimen should be sent for culture and sensitivity.
Urethral obstruction may be associated with red blood cells (RBCs) in the urine. The presence of glucose suggests diabetes mellitus. A random or first-morning specific gravity greater than 1.020 excludes diabetes insipidus.
Ultrasonography
Failure to empty the bladder is a significant risk factor for cystitis and is common in patients with overactive bladder, dysfunctional voiding, neurogenic bladder, or urethral obstruction. Portable bladder ultrasonography (US) is available to assess residual urine when the patient is in the office. The residual volume of urine is normally less than 5 mL.
Diagnostic imaging studies are not routinely indicated; however, patients with coincidental daytime voiding symptoms should undergo US of the bladder and kidneys before and after voiding. In patients with significant daytime symptoms whose ultrasonograms are normal, more invasive investigations should be deferred for 3 months, during which period the voiding routine and emptying are improved, cystitis is treated or prevented, and bowel health is improved.
Voiding Cystourethrography and Plain Radiography
If the bladder wall is thickened or trabeculated on US or a significant postvoid residual volume (>50 mL) of urine is noted, voiding cystourethrography (VCUG) should be considered.
VCUG is warranted for patients in whom a neurogenic bladder is suspected. The lumbosacral spine should be visualized during the procedure to look for sacral agenesis or spinal dysraphism. The classic radiologic feature of a neurogenic bladder is a trabeculated bladder with a Christmas-tree or pine-cone configuration. VCUG is also warranted when urethral obstruction is suspected on the basis of an abnormal urinary stream or abnormal findings on US.
If obstructive sleep apnea (OSA) is suspected, lateral radiography of the neck or referral to a pediatric otolaryngologist for direct visualization of the nasopharynx should be considered. Referral to a pediatric sleep specialist should also be considered.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) of the spine is indicated in any patient with any of the following:
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An abnormal neurologic examination finding of the lower extremities
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A visible defect in the lumbosacral spine
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The triad of encopresis, gait abnormality, and daytime symptoms
MRI should be considered in patients with significant daytime voiding dysfunction that does not improve with treatment, even if neurologic and orthopedic examination findings are normal.
Urodynamic Studies and Cystoscopy
Urodynamic studies help clarify the diagnosis of neurogenic bladder. A video urodynamic study measures both filling-phase parameters (eg, bladder capacity, presence or absence of unstable detrusor contractions, bladder compliance, and the state of the bladder neck) and voiding-phase parameters (eg, voiding pressures, bladder emptying, and the state of the external urethral sphincter).
Urodynamic studies and cystoscopy should be reserved for patients with urethral obstruction and neurogenic bladder. They are not recommended in children who have bedwetting as their only symptom.
Uroflowmetry
Uroflowmetry is a simple, noninvasive measurement of urine flow that is helpful in screening patients for neurogenic bladder and urethral obstruction. It is performed by having the child void into a special toilet with a pressure-sensitive device at the base.
A normal uroflow study shows a single bell-shaped curve with a normal peak and average flow rate for age and size. Children must be instructed to void when the bladder is full but not overfull; the uroflow curve in an overfull bladder can be tower-shaped or broad, and this can confuse the interpretation. Patients with dysfunctional voiding, urethral obstruction, or neurogenic bladder have prolonged curves or an interrupted series of curves and low peak and average urine flow rates.
Tables
Age, y |
Dry by Day, % |
Dry by Night, % |
2 |
25 |
10 |
2.5 |
85 |
48 |
3 |
98 |
78 |
Causes of Primary Enuresis |
Causes of Secondary Enuresis |
Idiopathic Disorder of sleep arousal Nocturnal polyuria Small nocturnal bladder capacity |
Idiopathic Disorder of sleep arousal Nocturnal polyuria Small nocturnal bladder capacity |
Overactive bladder or dysfunctional voiding |
Overactive bladder or dysfunctional voiding |
Cystitis |
Cystitis |
Constipation |
Constipation |
Neurogenic bladder |
Psychological |
Urethral obstruction |
Acquired neurogenic bladder |
Psychological |
Seizure disorder |
Ectopic ureter |
Obstructive sleep apnea |
Diabetes insipidus |
Diabetes mellitus |
|
Acquired diabetes insipidus |
|
Acquired urethral obstruction |
