What investigations should be done for a pediatric patient presenting with enuresis and chronic constipation?

Initial Investigation for Pediatric Enuresis with Chronic Constipation

Start with urinalysis as the mandatory first investigation, followed by treatment of the constipation, and reserve MRI spine only if there are specific neurological red flags on physical examination. 1

Primary Investigation: Urinalysis

Every enuretic child requires screening urinalysis as the sole obligatory laboratory test. 1

• A negative dipstick for leukocyte esterase and nitrite has 95-98% negative predictive value for urinary tract infection, making it highly reliable for ruling out infection 1, 2
• Urinalysis screens for diabetes mellitus, urinary tract infection, and kidney disease—all critical conditions that can present with enuresis 2
• Send urine culture concurrently with urinalysis given the logistic difficulty of obtaining culture after the office visit 1

Physical Examination Findings That Guide Further Testing

The physical examination must specifically assess for neurological red flags before ordering MRI spine. 1

Critical findings requiring MRI spine include:

• Sacral dimple or other suggestion of vertebral/spinal cord anomaly on back examination 1, 3
• Subtle neurologic dysfunction on thorough neurologic examination 1
• Continuous day-and-night wetting pattern combined with sacral abnormalities 3

Palpate the abdomen for fecal impaction, as constipation commonly coexists with enuresis and contributes to symptoms. 1, 4

When to Order MRI Spine

MRI spine is indicated immediately only when physical examination reveals a sacral dimple or other signs of occult spinal dysraphism, particularly with non-monosymptomatic enuresis (daytime and nighttime symptoms). 3

• The combination of sacral dimple with bowel and bladder dysfunction represents a red flag for tethered cord or lipoma 3
• Do not delay imaging with prolonged behavioral interventions when these red flags exist 3
• Without these specific neurological findings, MRI spine is not part of the initial workup 1

Role of Kidney Ultrasound

Kidney ultrasound has no role in initial evaluation unless structural abnormalities are suspected based on history, physical examination, or urinalysis findings. 2

• Ultrasound is not indicated for routine enuresis evaluation 2
• Reserve imaging for complex cases refractory to initial therapy or when urinalysis suggests anatomical problems 5

Address the Constipation Component

Constipation treatment should be prioritized as it directly impacts urinary symptoms. 4, 6

• Nocturnal enuresis occurs in 22.5% of children with chronic functional constipation 6
• Constipation treatment led to resolution of nocturnal incontinence in 63% of cases 4
• Physical pressure from fecal masses affects bladder emptying and can cause urinary symptoms 4
• Treatment includes fecal disimpaction with polyethylene glycol or enemas, followed by maintenance laxative therapy 4

Critical Pitfalls to Avoid

• Do not attribute enuresis to behavioral causes when accompanied by daytime symptoms (3-4 times daily wetting) without proper investigation 2, 3
• Do not order MRI spine routinely without specific neurological findings on examination—this represents unnecessary imaging and cost 1
• Do not skip urinalysis thinking constipation explains everything—urinary tract infection and diabetes must be excluded 1, 2
• Untreated constipation can lead to recurrent urinary tract infections and worsening symptoms 4, 7

Diagnostic Algorithm Summary

1. Obtain urinalysis (with culture) immediately 1, 2
2. Perform thorough physical examination focusing on:
   • Abdominal palpation for fecal impaction 1, 4
   • Back examination for sacral dimple or spinal anomalies 1, 3
   • Complete neurologic examination 1
3. Order MRI spine only if sacral dimple or neurologic abnormalities found 3
4. Initiate constipation treatment regardless of other findings 4
5. Kidney ultrasound only if urinalysis abnormal or structural concerns 2