What is the next investigation for a 6-year-old patient with diurnal and nocturnal enuresis and a sacral dimple?

Lumbar MRI is the Next Investigation

In a 6-year-old with both daytime and nighttime enuresis plus a sacral dimple, lumbar spine MRI should be performed immediately to rule out tethered cord or other occult spinal dysraphism before pursuing other investigations. 1

Clinical Reasoning

The combination of diurnal and nocturnal enuresis (bedwetting all day and night) with a sacral dimple represents a red flag for underlying neurological pathology, specifically tethered cord syndrome. 1

Why Lumbar MRI Takes Priority:

• Sacral dimples with bowel and bladder dysfunction warrant lumbar spine MRI to exclude tethered cord, particularly when combined with continuous incontinence patterns. 1

• This child has non-monosymptomatic enuresis (NMNE) due to daytime symptoms, which demands more aggressive investigation than isolated nighttime wetting. 1

• The continuous nature ("all day and night") suggests severe dysfunction beyond typical developmental enuresis—this pattern indicates either neurogenic bladder or severe anatomical/functional abnormality. 2

• Children with continuous incontinence or weak stream require specialized evaluation without delay, as these are alarming symptoms distinct from typical enuresis. 1

Why Not Urine Analysis First:

While urine dipstick is the "sole obligatory laboratory test" for typical monosymptomatic enuresis 1, this clinical scenario is fundamentally different:

• Urine analysis cannot explain the sacral dimple or rule out neurological causes. 1

• The presence of a structural spinal anomaly (sacral dimple) with severe bladder dysfunction creates immediate concern for tethered cord, which requires urgent imaging to prevent permanent neurological damage. 1

• Delaying MRI to perform urinalysis first risks missing a time-sensitive neurosurgical condition. 1

The Appropriate Diagnostic Sequence:

1. Lumbar spine MRI immediately to evaluate for tethered cord, lipoma, or other occult spinal dysraphism 1

2. Urinalysis and culture can be performed concurrently but should not delay imaging 1, 3

3. Renal/bladder ultrasound to assess for hydronephrosis, bladder wall thickening, and post-void residual if MRI is normal 3, 2

4. Urodynamic studies if anatomical causes are excluded and symptoms persist 2, 4

Critical Pitfalls to Avoid:

• Do not attribute continuous day-and-night wetting to behavioral causes when a sacral dimple is present—this combination mandates neurological investigation. 1

• Do not delay imaging with prolonged behavioral interventions or empiric medications when red flags exist. 1, 2

• Do not assume spina bifida occulta is benign without imaging—while most children with spina bifida occulta and enuresis respond to conservative management, those with continuous symptoms and cutaneous markers require MRI to identify the minority who need neurosurgical intervention. 4

• Recognize that "focal neurologic findings, muscle weakness, abnormal deep tendon reflexes, and/or severe abnormalities in muscle tone" along with bowel/bladder dysfunction specifically indicate lumbar spine MRI. 1

Expected Findings and Next Steps:

• If MRI reveals tethered cord or lipoma, neurosurgical consultation is mandatory. 1, 4

• If MRI is normal, proceed with standard evaluation for severe NMNE including urodynamics, as this child likely has detrusor overactivity or dysfunctional voiding requiring specialized urological management. 2

• Even with normal imaging, this severity of symptoms (continuous day-and-night wetting at age 6) requires pediatric urology referral, not primary care management alone. 1, 2