What is the next step in managing a patient with diurnal and nocturnal enuresis, chronic constipation, and a sacral dimple (dimple on the lower back)?

Lumbosacral MRI

The most appropriate next step is lumbosacral MRI (Option B) to rule out tethered cord and other spinal dysraphism before initiating any other treatment. 1

Rationale for Immediate Imaging

The combination of day and night enuresis, chronic constipation, and a sacral dimple constitutes a red flag constellation requiring urgent neurological evaluation before symptomatic management. 1

• Sacral dimples can indicate underlying spinal cord pathology, particularly tethered cord syndrome, which presents with bowel and bladder dysfunction. 1
• The American Academy of Child and Adolescent Psychiatry guidelines explicitly state that examination of the back for sacral dimple or other suggestion of vertebral or spinal cord anomaly is essential in every enuretic child. 1
• The 22q11.2 deletion syndrome guidelines (applicable to general pediatric neurology principles) specifically recommend: "In those with bowel and bladder dysfunction/lower limb upper motor neuron signs, lumbar spine MRI should be considered to rule out tethered cord, especially when a sacral dimple is present." 1

Why Not the Other Options First

Option A (Treat Constipation): Premature Without Ruling Out Structural Pathology

• While constipation treatment can resolve enuresis in some cases 1, 2, treating constipation before excluding tethered cord could mask progressive neurological deterioration. 1
• Constipation is significantly associated with non-monosymptomatic enuresis (daytime + nighttime wetting) 3, 4, but the presence of a sacral dimple changes the diagnostic priority entirely. 1
• If tethered cord is present, the constipation is a neurogenic symptom requiring surgical intervention, not medical management alone. 1

Option C (Spinal Ultrasound): Inadequate for This Age Group

• Spinal ultrasound is only useful in infants under 3-6 months before vertebral ossification obscures visualization. 1
• For school-age children with suspected spinal dysraphism, MRI is the definitive imaging modality. 1

Option D (Urinalysis and Culture): Insufficient as Initial Step

• While urinalysis is part of the standard enuresis workup 1, it does not address the structural neurological concern raised by the sacral dimple. 1
• Urinary tract infections are relatively uncommon in constipated enuretic children (5.8% in one study) 2, and normal urinalysis does not exclude tethered cord. 1

Clinical Algorithm

1. Perform thorough neurological examination looking for:

   • Lower limb weakness or asymmetry 1
   • Abnormal deep tendon reflexes 1
   • Gait abnormalities 1
   • Foot deformities (pes planovalgus, clubfoot) 1
   • Muscle tone abnormalities 1

2. Order lumbosacral MRI immediately if sacral dimple is present with bowel/bladder dysfunction, regardless of whether focal neurological signs are detected on examination. 1

3. After excluding structural pathology, then proceed with:

   • Urinalysis and culture 1
   • Treatment of constipation if present 1
   • Behavioral interventions for enuresis 1

Critical Pitfalls to Avoid

• Never assume a sacral dimple is benign in the presence of bowel and bladder dysfunction—this triad mandates imaging. 1
• Do not delay imaging to first attempt conservative management, as progressive tethered cord can cause irreversible neurological damage. 1
• Do not rely on normal neurological examination alone to exclude spinal dysraphism—subtle findings may be missed, and MRI is required for definitive evaluation. 1