Definition and Classification

Nocturnal enuresis (NE) is defined as involuntary urinary incontinence during sleep.
It occurs in a child aged five years or older.
The frequency must be at least one episode per month.
Primary enuresis refers to children who have never achieved nocturnal urinary control.
Secondary enuresis occurs when bedwetting begins after a minimum six-month period of dryness.
Monosymptomatic nocturnal enuresis (MNE) presents with no other lower urinary tract symptoms.
Non-monosymptomatic nocturnal enuresis (NMNE) is associated with daytime symptoms.
These daytime symptoms include urgency, daytime incontinence, voiding difficulties, or an abnormal voiding pattern.

Epidemiology

Nocturnal enuresis is a multifactorial condition.
It is classically described by a three-factor model involving sleep, bladder capacity, and urine production.

Pathogenic Factor	Mechanism
Nocturnal Polyuria	Caused by reduced antidiuretic hormone (ADH) production at night. This leads to an abnormally large diuresis during sleep.
Reduced Bladder Capacity	The bladder exhibits a reduced functional reservoir capacity during nighttime. This mechanism is prominent in non-monosymptomatic enuresis.
Sleep and Arousal Deficits	Children exhibit defective sleep arousal. They cannot awaken to the sensation of a full bladder. Sleep fragmentation and periodic limb movements are frequently observed.
Genetic Factors	Genetic variations are linked to chromosomes 6, 12, 13, and 22. Variants in genes like PRDM13 may influence sleep, urine production, and bladder function.

Sleep-disordered breathing and obstructive sleep apnea are associated with nocturnal enuresis.
Bladder bowel dysfunction is a frequent comorbidity.
This includes chronic constipation and fecal incontinence.
Enuresis is also associated with behavioral conditions like attention deficit hyperactivity disorder (ADHD).

A careful history must assess the pattern of enuresis and fluid intake at night.
It should evaluate for snoring and symptoms of obstructive sleep apnea.
Physical examination should rule out occult spinal dysraphism.
Signs include lumbosacral hair tufts, gluteal cleft asymmetries, or abnormal lower extremity neurology.
A rectal examination or ultrasound can evaluate for fecal impaction and constipation.

Urinalysis is performed to exclude polyuria, glycosuria, and urinary tract infection.
A 48-hour frequency-volume chart records daytime bladder function and drinking behavior.
Home recordings of diaper weights and first morning void volumes are used to estimate nocturnal urine production.

The family and child must be reassured that the condition is self-limited.
Punitive measures must be strictly avoided to prevent adverse psychological effects.
Fluid intake should be restricted to two ounces after 6 PM.

Therapy Type	Description and Efficacy
Motivational Therapy	Uses a star chart for dry nights to encourage the child.
Enuresis Alarm	A moisture sensor in the underwear activates an alarm when voiding begins. It trains the child to awaken. Success rates range from 30% to 60%.
Desmopressin Acetate	A synthetic ADH analog that reduces overnight urine production. It is highly effective for patients with nocturnal polyuria. Nighttime fluid restriction is mandatory during use.
Anticholinergic Drugs	Medications like oxybutynin or tolterodine are used for therapy-resistant cases. They are indicated for children with an overactive bladder or reduced bladder capacity.
Imipramine	A tricyclic antidepressant with mild anticholinergic effects. It reduces urine output slightly but carries a risk of potentially lethal cardiotoxicity on overdose.

Modality	Common Causes of Failure
Alarm Failure	Parents fail to wake the child. The alarm is not used every night. The therapy is stopped too soon (less than 8 weeks).
Desmopressin Failure	The patient has reduced nocturnal bladder capacity instead of polyuria. The patient consumes large volumes of fluids in the evening. Undiagnosed obstructive sleep apnea is present.