Medical Library Home | Table of Contents

Nocturnal Enuresis

Judith D. Laval, MD

Nocturnal enuresis is defined as the involuntary passage of urine during sleep. Diurnal enuresis refers to the involuntary or intentional voiding of urine into clothing while awake. Primary nocturnal enuresis is bed-wetting that has been present since birth, and secondary nocturnal enuresis is enuresis that occurs after being dry for a minimum of 6 months. Evaluation of nocturnal enuresis is usually not necessary unless the problem persists after 3 years of age.

Prevalence/Epidemiology

Most bed-wetting is due to a maturational delay, and it becomes less frequent with each passing year of life.

At age 5, 20% of children wet the bed at least monthly, with 5% of boys and 1% of girls wetting the bed nightly. By age 6, only 10% of children wet the bed. Thereafter, 15% of bed-wetters become dry each year. Overall, 60% of bed-wetters and more than 90% of nightly bed-wetters are male.

Etiology

Physiologic Enuresis

Most children who have primary nocturnal enuresis have no disease mechanism to explain the enuresis, and they are considered to have physiologic enuresis. Enuresis results from inability to recognize the sensation of a full bladder during sleep and to awaken from sleep to urinate into the toilet. Those children who wet nightly usually also have a small bladder, which is unable to hold all the urine produced during the night. Clues to a small capacity are daytime frequency, and wetness every night.

Enuresis has a genetic predisposition. If one parent was a bed-wetter, the probability of offspring having enuresis is 45%. If both parents were bed-wetters, the probability of enuresis is 77%.

Evaluation of Nocturnal Enuresis

History For Organic Factors

Symptoms of dysuria, intermittent daytime wetness, polydipsia, polyuria, CNS trauma, constipation, and encopresis may indicate medically treatable conditions.

Constant wetness or dampness (ectopic ureter), an abnormal urine stream with dribbling or hesitancy (posterior urethral valves), or a change in gait (spinal tumor) may indicate surgically treatable conditions.

Physical Examination

Abdominal examination may reveal a distended bladder or fecal impaction. Examination of the lumbosacral area may reveal a midline defect. Gait, muscle tone, strength, and deep tendon reflexes in the lower extremities should be assessed.

External genitalia should be examined for meatitis, vulvitis, labial adhesions, or signs of sexual abuse.

If the urine stream is abnormal by history, it should be observed. Rectal examination should be performed if encopresis or constipation is reported.

The dorsum of the feet should be examined for pitting edema. The patient should be examined for obligatory mouth breathing because such children may wet themselves during sleep apnea and be cured by adenoidectomy.

Laboratory Tests

Every child who has enuresis should have a urinalysis. Absence of glucose rules out diabetes. A specific gravity of 1.015 or greater rules out diabetes insipidus. A urine culture should be obtained if symptoms of UTI are present, the urine has a foul odor, a nitrite or leukocyte esterase dipstick test is positive, or the patient has had a UTI in the past.

Imaging Studies

Voiding cystourethrogram is reserved for children who have symptoms or signs suggestive of urinary tract obstruction or a neurogenic bladder.

Bladder ultrasonography (pre- and postvoiding) to rule out partial emptying is reserved for children who have diurnal enuresis unresponsive to treatment.

Confirmation of Physiologic Enuresis

More than 97% of children do not have a physical cause for their nocturnal enuresis.

Functional Bladder Capacity. The parents should measure functional bladder capacity at least three times before the initial physician evaluation. If this step has not been done, have the child drink 12 oz of water upon arrival for evaluation and measure the volume of urine when the child reports the need to urinate. The normal bladder capacity in ounces is the age plus 2. Normal adult bladder capacity is 12 to 16 oz. If the bladder capacity is normal, the problem usually responds to simple motivational techniques. If bladder capacity is smaller than normal, treatment is more difficult, but parents and child often are relieved to learn that the bed-wetting has a physical explanation.

 

Nondrug Management of Nocturnal Enuresis

From age 3 or 4 years onward, the parents should be reassured that bed-wetting is due to a maturational delay and that it is not intentional. They should be warned about the inappropriateness of any punishment, which can cause psychological scars.

Getting up at night can compensate for a small bladder. The smaller the child's bladder, the more important it is for him to learn to awaken at night. No child can be cured completely until he learns how to awaken spontaneously, locate the toilet, and urinate there.

Improve access to the toilet. Put a nightlight in the bathroom. If the bathroom is at a distant location, put a portable toilet in the child's bedroom.

Avoid excessive fluids two hours before bedtime. Eliminate caffeine-containing beverages that would increase urine production. Normal fluid intake should be allowed. Fluid restrictions should be elected by the child, not imposed.

Empty the bladder at bedtime. The parents may need to remind the child and put a sign at their bedside or on their bathroom mirror.

Take the child out of diapers or pull-ups. These items can interfere with motivation for getting up at night.

Include the child in morning cleanup. Including the child as a helper in stripping the bedclothes and putting them into the washing machine provides a natural disincentive for being wet. The mattress can be protected with a plastic cover.

Preserve self-esteem. Support, encouragement, and an understanding that the problem is due to a small bladder are important.

Self-awakening or Parent-awakening Programs

Self-awakening. Ask children to rehearse a particular sequence of events every night before going to sleep. The child lies in bed with eyes closed and pretends that it is the middle of the night and the full bladder is trying to wake him up by starting to hurt. He then goes to the bathroom and empties the bladder.

Parent-awakening is indicated if self-awakening fails. The parent should awaken the child, but the child must locate the bathroom. The child should be awakened at the parents' bedtime each night. At that point, the child is either cured or ready for an enuresis alarm.

Enuresis Alarms

Small alarms that are worn on the body are available to help teach children to awaken to the sensation of a full bladder. Most of them are audio alarms (eg, Nytone or Wetstop). One alarm (The Potty Pager) is a vibrating alarm. It has the advantage of not awakening the entire household.

Enuresis alarms have the highest cure rate of any treatment, with a 84% cure rate.

Drug Therapy

Desmopressin

Desmopressin (DDAVP), the synthetic analog of vasopressin, reduces urine production by increasing water retention. The odorless drug is administered intranasally. The starting dosage for all ages is 20 mcg, or one spray in each nostril, at bedtime. The dosage can be increased by 10 mcg weekly to a maximum total dose of 40 mcg if the patient is unresponsive and can be decreased if nasal or abdominal discomfort occurs. For any patient who remains completely dry on a given dose, a dose of 10 mcg less should be tried.

Twenty four percent of children are completely dry while on medication, and 94.3% relapse after desmopressin is discontinued.

Side effects are rare. Symptomatic hyponatremia has been reported in a few patients. It is contraindicated in habit polydipsia, hypertension, or heart disease. Mild side effects include headache, abdominal discomfort, nausea, and nasal discomfort; these occur in fewer than 5% of patients. Desmopressin costs about $1.50 per spray.

Imipramine

Imipramine combines an anticholinergic effect that increases bladder capacity. Imipramine is taken 1 hour before bedtime. The starting dosage is usually 25 mg per day. The maximum dosage is 50 mg/day for children from 8 to 12 years of age and 75 mg/day for children older than 12. Initial cure rates are 10-60%. Relapse rates are 90%.

The low toxic/therapeutic ratio of imipramine raises concerns. Imipramine should be avoided in children younger than 5 years of age because overdose is often fatal in this age group. The symptoms of overdosage include ventricular tachycardia, coma, and seizures.

Clinical Use of Drug Therapy

Desmopressin and imipramine have similar efficacy. Imipramine has the advantage of lower cost and ease of administration; desmopressin has the advantage of minimal side effects. Combination of the two may be useful for children who do not respond to either drug alone.

Intermittent use of drugs is appropriate for children older than age 8 who need them for special occasions, such as camping, school trips, vacations, and overnights.

Combination drug and enuresis alarm therapy is especially helpful for older children who have nightly enuresis.

Efficacy of Various Treatments. Untreated bed-wetting also gradually resolves with time. Of the 7% of 8-year-olds who wet their beds, 15% have a spontaneous cure each year.

§