Urinary incontinence and bed-wetting
By Cynthia Pan, MD
Starting the discussion with parents and patients
A recent survey conducted of 745 parents of children between the ages of 3-14 showed that parents are reluctant to discuss the problem of bed-wetting with their health care provider. When learning of the incidence in children 6 years and older, 53 percent of parents thought providers needed to be more proactive in addressing this problem. The stigma attached to this problem may be a barrier, as evidenced by the majority of parents saying they were "not too comfortable" or "not comfortable at all" letting friends or other parents know their child has bed-wetting issues. Despite 82 percent of parents saying they would "probably" or "definitely" want their provider to talk with them if their child was bed-wetting past 6 years old, less than half would schedule a visit specifically to address the problem. The reluctance to discuss this issue can be remedied by physicians providing opportunities for parents during health screenings to ask questions and receive information.
Voiding physiology
During storage, the detrusor is relaxed and the capacity of the bladder allows urine to be held for several hours. Micturition then is coordinated and voluntary, with detrusor contraction and sphincter relaxation occurring in a coordinated fashion resulting in complete bladder emptying.
Though the neural innervation of the bladder is predominantly autonomic, bladder function is under control of cortical function. A complex integration of visceral and somatic innervation is necessary for normal voiding, perhaps explaining a wide spectrum in the accomplished age for urinary continence.
Evaluation of urinary incontinence
| Table 1 |
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Etiologies of urinary incontinence
With polyuria
Metabolic disorders
Diabetes mellitus
Central diabetes insipidus
Hypercalcemia
Hypokalemia
Renal concentrating defect
Nephrogenic diabetes insipidus
Genetic
Secondary
Without polyuria
Primary nocturnal enuresis*
Dysfunctional voiding syndromes
Neuropathic bladder
Anatomic defects of the urinary tract
*Some may be characterized by nocturnal polyuria. |
History
The history should begin with careful questioning to determine whether the patient has polyuria, the excessive production of urine. This will separate metabolic and renal disorders from disorders of voiding and lower urinary tract abnormalities.
Polyuria can result from the absence of release of antidiuretic hormone (ADH), the failure of the kidney to respond to ADH or an osmotic diuresis. The symptom of polyuria naturally results in polydipsia. Both symptoms often are associated in young children with urinary incontinence. Waking to seek fluids at night in a consistent pattern also is a sign of polydipsia. Parental stories of bed linens being soaked despite a "double diaper" or training pull-on diaper, lend clues to polyuria.
An osmotic diuresis leading to polyuria may be an early sign of diabetes mellitus. Diabetes insipidus, both nephrogenic and central, leads to the production of very large amounts of hypotonic urine. These patients also can present with enuresis and easily develop complications of hypernatremia, dehydration and failure to thrive. Acquired and secondary forms of nephrogenic diabetes insipidus such as renal cystic disease, sickle cell disease or chronic pyelonephritic scarring, may have urinary incontinence as the only symptom.
Taking a voiding history
In the absence of polyuria, a detailed history of voiding habits will help dictate the proper evaluation. Determining whether incontinence is isolated to daytime or nighttime is important in determining further evaluation. If daytime symptoms are present, detailed facts about both bowel and bladder elimination should be obtained. Voiding frequency sometimes is difficult to ascertain and an assignment to keep a diary of voiding can be given on the first visit. This also should include information on both bladder and bowel habits, specifically urine volumes and when urinary incontinence occurs. Urine holding patterns with overflow incontinence are most easily identifiable with a diary. Other urinary symptoms such as dysuria, urgency, dampness in the underwear or signs of urinary tract infection all can be signs of dysfunctional elimination. Asking specifically if there is the sudden urge to void followed by incontinence or maneuvers to prevent urine leakage, such as squatting and pressing the heel of the foot into the perineum, will provide clues to a hyperactive detrusor activity.
| Table 2 |
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Indications of secondary enuresis
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Secondary enuresis is defined as enuresis occurring after a dry period of at least six consecutive months and can be the first sign of an acquired renal or metabolic disease. Fecal soiling or constipation may be an accompanying sign of dysfunctional elimination, but should first raise suspicion for an occult spinal lesion such as spina bifida or a tethered cord. Additionally, continuous dribbling, a poor urinary stream, or recurrent infections may be a sign of anatomic or neuropathic lesions and symptoms indicating possible serious disease.
Physical examination
All patients should have their growth evaluated, as failure to thrive can be seen in many of the metabolic disorders. Blood pressure measurements should be performed for underlying renal and urologic abnormalities. Careful attention should be given to the lower back, abdomen, gait and reflexes. Certain physical findings raise suspicion for underlying anatomic abnormalities.
| Table 3 |
Physical findings indicating possible anatomic lesions
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Social stressors or psychiatric disorders such as ADHD should be ascertained, as evidence supports the importance of psychological factors in the occurrence of secondary enuresis. Most children with primary nocturnal enuresis are emotionally well-adjusted. Yet care should be taken to not underestimate the sequelae of enuresis in the older school-aged child, who may develop low self-esteem as a result of feeling "abnormal" among peers. Evaluation always should include asking how the patient and family members are coping with the problem and whether it is interfering with social or school issues.
Diagnosis
Determination as to whether polyuria (or polydipsia) is present will help guide the necessary laboratory and radiologic testing. A water deprivation test to examine urine concentrating capacity of patients in which diabetes insipidus is suspected, should be done in a hospital setting. For those patients with a less suspect history of polyuria, a first morning void after an overnight fast should be sufficient to check urine osmolarity or specific gravity.
In some patients, a home voiding diary can be very informative in defining the problem, which outlines how often and how much they are voiding, and when urinary incontinence and constipation or encopresis occurs.
Laboratory assessment
Routine laboratory examination is very basic and in most cases will be unrevealing. When polyuria or polydipsia is present, appropriate blood chemistries are important and screen for diabetes mellitus and electrolyte disorders seen in secondary forms of polyuric renal syndromes such as renal tubular acidosis or Bartters syndrome. Hyperna-tremia can be seen in the severe forms of nephrogenic diabetes insipidus.
Secondary disease will be absent in most cases of urinary incontinence and enuresis, and therefore in the absence of polyuria, diagnostic screening for infection or renal disease usually can be accomplished with a urinalysis and urine culture. Hematuria or proteinuria can be signs of renal disease, though its absence does not exclude this possibility. Glucosuria, when associated with normal serum glucose, can indicate tubulointerstitial disease, where proximal tubular injury results in a lowered threshold for glucose reabsorption.
Imaging and other diagnostics
Radiologic imaging is not necessary in patients with pure primary nocturnal enuresis. In select patients with daytime symptoms or a suspect history or urinalysis, a renal ultrasound may provide information regarding acquired or congenital renal diseases. Images of the bladder can reveal urologic abnormalities including poor bladder emptying or thickened bladder wall. A voiding cystourethrogram only is indicated in patients with a questionable urinary stream, continuous dribbling (aberrant ectopic ureter) or spinal cord lesions and lower neurologic signs. Magnetic resonance imaging of the lower spine also should be reserved for those patients with cutaneous signs, neurologic or orthopedic symptoms of the L-S spine or complex bony spinal deformities seen on plain X-ray. Cystometry exam is reserved for a select group of patients with a history of dysfunctional voiding symptoms whose response to therapy is poor. Bladder instability is characterized by involuntary contractions at greater than 15 cm water pressure during filling. Small bladder capacity almost always is a functional problem, not anatomic, and is based on the normal volume estimated for that age.
Treatment
Primary nocturnal enuresis
First, establish whether primary nocturnal enuresis (PNE) is the only symptom or whether there are associated symptoms such as diurnal incontinence, constipation, sleep disorders or behavioral issues such as ADHD before developing a treatment strategy.
Second, reassurance that the patient will "outgrow" PNE and a search for any organic cause may be enough for the patient and family to wait and observe only. Positive reinforcement for dry nights and dispelling any negative attitudes and blame toward the child will enhance self-esteem. If treatment is sought, bed alarms have a high success rate, but patient selection is important. These devices are designed to awaken patients when micturition begins, and result in patients developing increased bladder capacity. Its effect may not be seen for up to 12 weeks and therefore requires a highly motivated family and patient. The older patient who is ready to take charge of the problem and who does not have difficulty waking is a prime candidate.
Pharmacologic therapy includes the use of a vasopressin analogue, DDAVP. There is likely a subpopulation of enuretics that have "nocturnal polyuria" which led to its early popularity, but there is recent evidence that this is independent of vasopressin secretion. Nonetheless, several factors seem to influence its effectiveness such as a positive family history of PNE, normal bladder capacity and age greater than 7 years. Its safety profile has been excellent but patients should be given careful instruction on limiting intake after the bedtime dose.
Patients with small bladder capacity and diurnal symptoms tend to be nonresponders, and these patients may benefit from anticholinergic therapy, such as oxybutinin. Combination therapy using bed alarm plus vasopressin analogue, or vaspressin analogue plus anticholinergic therapy, may be helpful in select patients.
Imipramine, a tricyclic antidepressant, has been shown to be effective, but its side effects and toxicity has kept it a less optimal choice. Patients with enuresis and other behavioral problems when placed on selective serotonin reuptake inhibitors (SSRIs) have reported improvement in their enuresis and may offer treatment in this population with a lesser side effect profile.
Dysfunctional voiding
Treatment of mild voiding dysfunction should begin with non-pharmacologic management. Educate patients to void frequently and regularly every 1-2 hours at the start, before they feel the urge to void. This encourages voiding when they are relaxed and will lead to fewer contractions of the external sphincter during micturition. Keeping a voiding schedule diary allows the child to be more aware of his or her bladder habits. Aggressive management of constipation is imperative to good bladder emptying and avoiding bladder instability.
When incontinence continues despite non-pharmacologic methods, anticholinergic therapy should be added in the child with an overactive or unstable bladder. Oxybutinin should be started at a low dose and titrated to its maximum dosage if needed, the latter possibly leading to side effects.
Biofeedback can be reserved for those with moderate to severe dysfunctional voiding. Patients can learn to increase bladder capacity and inhibit detrusor contractions through this method. It also has been proposed in patients with both nocturnal enuresis and daytime symptoms.
Education and open discussion involving the child is the key to successful management. A provider can make a large impact in a child's progress by developing a treatment plan, helping parents set attainable goals, following the child's progress closely during treatment, and finally, by giving praise to the patient when success is met.
References
Healthcare Providers Need to be More Proactive in Discussing Bedwetting. For Release.com; Philadelphia, July 30, 2005 PR newswire.
Pan C. Polyuria and Urinary Incontinence. Practical Strategies in Pediatric Diagnosis and Therapy; second edition. eds Kliegman R, Greenabaum LA, Lye P. Elsevier Saunders, Philadelphia, PA 2004; pps.1133-1140
Schulman SL, Quinn CK, Plachter N, Kodman-Jones C. Comprehensive management of dysfunctional voiding. Pediatrics 1999;103(3):658.
Austin PF, Ritchey ML. Dysfunctional voiding. Pediatrics in Review 2000;21;336-340.
Butler RJ, Holland P. The three systems: a conceptual way of understanding nocturnal enuresis. Scand J Urol Nephrol 2000;34:270-77.
Tullus K, Bergstrom R, Fosdal I, Winnergard I, Hjalmas K for the Swedish Enuresis Trial Group. Efficacy and safety during long-term treatment of primary monosymptomatic nocturnal enuresis with desmopressin. Acta Pediatr 1999;88:1274-1278.
 Cynthia Pan, MD, is medical director of Nephrology/Renal/Dialysis at Children's Hospital of Wisconsin. She also is an associate professor of Pediatrics (Nephrology) at the Medical College of Wisconsin. Member, Children's Specialty Group.
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