What could be causing my nocturnal enuresis (bedwetting) 2-3 times a month without any structural damage?

Adult Nocturnal Enuresis: Evaluation and Management

In a 39-year-old adult with nocturnal enuresis 2-3 times monthly without structural damage, the most likely causes are nocturnal polyuria, sleep disorders (particularly sleep apnea), overactive bladder with detrusor overactivity, medication effects, or a combination of these factors. 1, 2

Key Diagnostic Considerations

Primary Evaluation Steps

Your evaluation must focus on identifying the specific pathophysiologic mechanism:

• Complete a frequency-volume chart (bladder diary) for at least 2 days of measured intake/output to objectively detect nocturnal polyuria, defined as nighttime urine production exceeding 35% of total daily urine volume 3, 2

• Screen for sleep apnea, which is directly associated with nocturnal enuresis in adults through mechanisms involving arousal dysfunction and increased nighttime urine production 1, 4

• Review all current medications, as many drugs can contribute to nocturnal symptoms, including diuretics, hypnotics (which impair arousal to bladder distension), and medications affecting bladder function 1, 2

• Perform urinalysis to exclude urinary tract infection, diabetes mellitus, and kidney disease 1, 3

Critical Differential Diagnoses

Nocturnal polyuria is a leading cause in adults and results from:

• Excessive nighttime urine production from cardiovascular disease, venous insufficiency with lower extremity edema, or sleep disorders 1, 2
• Normal or large volume voids at night (as opposed to small volume voids seen in overactive bladder) 1

Overactive bladder (OAB) presents with:

• Urgency (sudden compelling desire to void that is difficult to defer) as the hallmark symptom 1
• Small volume nocturnal voids associated with detrusor overactivity 1, 5
• May have daytime urgency symptoms as well 1

Sleep disorders, particularly obstructive sleep apnea:

• Causes dysfunctional arousal patterns preventing awakening to bladder distension 1, 4
• Look for snoring, witnessed apneas, restless sleep, or daytime sleepiness 4

Physical Examination Priorities

• Abdominal examination for bladder distension or masses 1
• Assessment of lower extremities for edema, suggesting fluid redistribution contributing to nocturnal polyuria 1, 2
• Neurologic examination to exclude occult neurologic disease affecting bladder control 1

Additional Testing at Clinician Discretion

• Post-void residual (PVR) measurement should be assessed if you suspect incomplete emptying or have concerns about urinary retention 1
• Urine culture may be appropriate if urinalysis is unreliable or symptoms suggest infection 1

Treatment Algorithm Based on Identified Cause

For Nocturnal Polyuria

Behavioral modifications:

• Restrict fluid intake in the evening hours 3, 6
• Use afternoon diuretics (if medically appropriate) to shift fluid excretion earlier in the day 2
• Elevate legs in the afternoon to mobilize edema before bedtime 2

Pharmacologic treatment:

• Desmopressin 0.2-0.4 mg orally taken 1 hour before sleep (tablets) or 30-60 minutes before sleep (melt formulation) 3, 6
• Critical safety warning: Strictly limit fluid intake after taking desmopressin to avoid water intoxication, hyponatremia, and convulsions 3, 6

For Overactive Bladder

First-line behavioral treatments:

• Regular daytime voiding schedule 4, 6
• Bladder training techniques 1
• Voiding immediately before sleep 6

Pharmacologic treatment:

• Anti-muscarinic medications with active management of adverse events (dry mouth, constipation) 1
• Consider dose modification or alternate anti-muscarinic if effective but adverse events are intolerable 1
• Use with caution if PVR is 250-300 mL 1

For Sleep Apnea

• Refer for sleep study if screening suggests obstructive sleep apnea 4
• Treatment of the underlying sleep disorder (CPAP, surgical correction of upper airway obstruction) can lead to improvement or cure of enuresis 4

For Medication-Related Causes

• Discontinue or adjust hypnotics that may impair arousal to bladder distension 2
• Review and modify other medications contributing to symptoms 1

Common Pitfalls to Avoid

• Failing to identify nocturnal polyuria through proper bladder diary documentation leads to inappropriate treatment with bladder-focused therapies 3, 2

• Overlooking sleep disorders as a primary cause, particularly in adults where sleep apnea is common and treatable 1, 4

• Prescribing desmopressin without strict fluid restriction counseling risks serious hyponatremia and seizures 3, 6

• Not assessing for multiple contributing factors, as adult nocturnal enuresis is usually multifactorial requiring tailored treatment addressing each identified cause 2

Follow-Up and Monitoring

• Monthly follow-up is necessary to assess treatment response and adjust therapy 3, 6
• Continue treatment for at least 2-3 months before declaring failure 3, 6
• With desmopressin, use regular short drug holidays to assess ongoing need 3

When to Refer to Specialist

Urgent urology referral is indicated for:

• Continuous incontinence suggesting structural abnormality 3
• Recurrent urinary tract infections 3
• Abnormal neurological findings 3
• Refractory cases not responding to initial management 3, 6