Case Based Pediatrics For Medical Students and Residents
Department of Pediatrics, University of Hawaii John A. Burns School of Medicine
Chapter XIII.9. Enuresis
Potenciano Reynoso Paredes, MD
May 2002

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This is a 4.5 year old male who presents to the office with his mother with a chief complaint of bed-wetting twice a week. Essentially he is healthy except for an occasional cough and fever that the mother attributes to exposure to other children with colds. Urinary discharge occurs at night only and he therefore has to wear diapers to bed. His mother is worried since his brothers and sisters were all toilet trained by this age. There is no history of dysuria, intermittent daytime wetness, polyuria, or polydipsia.

His past medical history is unremarkable. Family history is significant for his father being a bed-wetter. His child development is normal.

Exam: VS T 37, P 110, R 20, BP 107/64, Ht 102 cm (25th percentile), Wt 16.2 kg (25th percentile). He is alert and active, in no distress. His appearance is non-toxic. HEENT and neck exams are negative. His lungs are clear bilaterally. His heart has a normal rate and rhythm, normal S1and S2, and no murmurs or rubs. No masses, organomegaly, or tenderness are appreciated on exam of his abdomen. Bowel sounds are present. He has no inguinal hernias. He has a circumcised penis of normal size. The meatus is normally placed, without discharge. No phimosis is present. His testes are descended bilaterally and are of normal size (Tanner stage 1). His back is straight with normal posture with no scoliosis or tenderness, or midline defects. His extremities and muscle tone are normal. His gait is normal. He is able to hop, skip, and stand on each foot for 5 seconds, copy a square and get dressed without help. His speech and behavior are age appropriate.

You reassure his mother that bladder control is usually attained between the ages of 1 and 5 years and bed-wetting becomes less frequent with each passing year. You recommend that she be supportive of her son's dry nights and avoid criticism of wet nights. You also recommend avoiding excessive fluid intake two hours before bedtime and emptying his bladder at bedtime. He returns to your office after 6 months and his mother feels that the bed-wetting problem has improved significantly. On his next appointment (4 months later) his mother reports the resolution of his bed-wetting problems.


Enuresis, commonly known as bed-wetting, is the most common childhood urologic complaint encountered by pediatricians. Nocturnal enuresis (NE) is defined as involuntary passage of urine during sleep beyond the age of expected continence which is approximately 5 years of age. There are two types of NE. Primary is when a child never stopped wetting for any lengthy period, whereas secondary is acquired enuresis after being dry for at least 6 months. Primary enuresis affects the large majority of children with enuresis.

Since urinary continence is reached earlier in girls than in boys, NE is 2-3 times more frequent in boys. At age 5, 20% have NE at least once a month, with 5% of boys nightly and less than 1% of the girls nightly. Since most NE is due to maturational delay, there is a significant resolution or improvement as the child gets older. Approximately 15% resolve each year. Interestingly, family studies show a strong genetic predisposition for enuresis. More recently studies suggest a genetic linkage of primary nocturnal enuresis to the short arm of chromosome 13.

Organic causes of bed-wetting account for less than 5% of all cases; with most being urinary tract infections. Other organic problems include: diabetes mellitus, diabetes insipidus, nocturnal seizures, genitourinary anomalies, nocturnal ADH deficiency, hyposthenuria (constant secretion of dilute urine) associated with sickle cell disease, medications, or emotional stress. These children need to be recognized and treated. Some children with severe constipation may compress the bladder and present with bed-wetting. Other theories suggest reduced bladder capacity or sleep disturbance.

The office evaluation of NE must exclude any organic causes. A careful history is taken which should include pattern of wetting, developmental milestones, fevers, polydipsia, polyuria, and prior urinary infections. Questioning about sickle cell disease, food allergy, and constipation is occasionally helpful. Attention should also be paid to family dynamics and stresses that may uncover psychological factors.

Physical examination should focus on the neurological, genital, bladder and bowel exams. Back examination should include a search for neurological involvement such as a midline defect or suggestions of an occult spinal dysraphism. A neurological examination that includes gait, muscle tone, strength, and perineal sensation should be done. Examination of external genitalia for abnormalities such as labial adhesions, meatitis, epispadias, and hypospadias should also be done. If possible, and the urine stream sounds abnormal by history, physicians should watch children void. The abdomen should be assessed for evidence of fecal impaction, organomegaly, or bladder distention.

The purpose of initial laboratory tests is usually limited to ruling out infection as the source of the problem. A specific gravity of 1.015 or greater rules out diabetes insipidus and the absence of glycosuria rules out diabetes mellitus. In cases in which urinary tract obstruction or neurogenic bladder are suspected, a voiding cystourethrogram may be warranted.

At present there is no treatment modality that is 100% successful. Again, parents need to be reminded that a majority of bed-wetting is due to maturational delay and not under conscious control. Therefore, the most important aspects of treatment are reassurance and protection of the child's self esteem. It is important that bed-wetting not be perceived as a bad behavior since punishment not only lowers the child self esteem, but also does nothing to improving symptoms. Early education of the parents in regards to maturational delay, role of genetics and the importance of a supportive toilet training practice may ease the difficult period. Remember that there is a 15% spontaneous remission every year so many advocate an approach of reassurance and watchful waiting. Some simple life adjustments such as improving access to the toilet, avoiding excessive fluid just before bedtime and emptying the bladder at bedtime may be tried initially.

To some families, this conservative approach (which requires patience) can lead to suffering and frustration. Instead, a comprehensive method of treatment that includes bladder training, pharmacologic therapy and behavior modification with an alarm system can be implemented.

Treatment can begin with positive reinforcement such as keeping a calendar and rewarding dry nights. Another treatment is bladder training consisting of different methods such as holding urine as long as possible then when the child does urinate he/she is suppose to stop and start the urine flow frequently. Another method is going to the bathroom several times a night, or having the parents wake the child several times during the night and subsequently lengthening the time interval between waking. The objective is to increase the muscle strength of the urethra as well as give the child confidence that he or she can control urine flow and link the feeling of a full bladder with the need to go to the bathroom. Average bladder capacity in children can be approximated by the formula: volume in ounces (30 ml per ounce) = 2 + age in years. Adult bladder capacity is about 250 to 400 ml.

Pharmacologic therapy consists of tricyclic antidepressants (imipramine) or desmopressin acetate (DDAVP). Each has advantages and disadvantages. Imipramine has anticholinergic effects on bladder capacity and noradrenergic effects which decrease bladder detrusor excitability. 10-60% respond favorably to imipramine treatment, but more than 90% relapse. Imipramine is also potentially lethal with acute overdose (especially cardiac toxicity). DDAVP is a synthetic analog of vasopressin stimulating water retention and urine concentration, thereby reducing urine volume. DDAVP is available in two forms, tablets and nasal spray. The oral form is often used on children with nasal congestion such as colds and allergies. The drawback is the cost and rare mild side effects of DDAVP. DDAVP is useful in certain situations such as a child going to overnight camp. There is a 25-50% success rate with DDAVP, but a relapse rate of 94%.

In recent years, enuresis alarms have been shown to be the most effective treatment for bed-wetting. Urination acts as a stimulus for the alarm and wakes the patient from sleep. The cure rate is 60-80% and it has the lowest relapse rate of 10-40% when compared to other treatments. The only drawback is that the child and family must be highly motivated to stay committed to these conditioning methods.


Questions

1. At what age do parents usually become concerned about bed-wetting?

2. True/False: Most nocturnal enuresis is due to organic causes.

3. Which drug for nocturnal enuresis is cardiotoxic?

4. What laboratory test should be done to evaluate a child with enuresis?

5. What is the bladder capacity of children?

6. In evaluating a chronic bed-wetting child, what should you look for in an abdominal exam?

7. True/False: Enuresis alarms produce excellent results if the child wakes up spontaneously when the alarm goes off.


References

1. Schmitt BD. Nocturnal Enuresis. Pediatr Rev 1997;18(6):183-191.

2. Wan J, Greenfield S. Enuresis and Common Voiding Abnormalities. Pediatr Clin North Am 1997;44(5):1117-1131.

3. Gimpel GA, Warzak WJ, Kuhn BR, Walburn JN. Clinical Perspectives in Primary Nocturnal Enuresis. Clin Pediatr 1998;37:23-30.

4. Ilyas M, Jerkins GR. Management of Nocturnal Childhood Enuresis in Managed Care: A New Challenge. Pediatric Annals 1996;25(5):260-264.

5. Novello AC, Novello JR. Enuresis. Pediatr Clin North Am 1987;34(3):719-733.

6. Weiss JC. Chapter 40 - Enuresis. In: Curry TA, Sargent AJ, Blum NJ, Fein JA (eds). Pediatric Primary Care A Problem-Oriented Approach, third edition. 1997, St. Louis: Mosby, pp. 253-257.

7. Mikkelsen EJ. Chapter 54 - Modern Approaches to Enuresis and Encopresis. In: Lewis ML (ed). Child And Adolescent Psychiatry: A Comprehensive Textbook, second edition. 1996, Baltimore: Williams & Wilkins, pp. 593-597.


Answers to questions

1. Typically at age 5 or 6 years.

2. False.

3. Imipramine.

4. Urinalysis with specific gravity, glucose, protein, blood and white cells.

5. Most adults have a bladder capacity between 250-400 ml, but the average bladder capacity in children can be approximated by the formula: volume (oz.) = 2 + age in years.

6. The abdominal exam should asses for masses secondary to enlarged urinary organs (bladder, kidney) and for evidence of palpable stool in the colon suggesting fecal impaction.

7. True.


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