What are the current guidelines for managing a sacral dimple in a 6-day-old neonate?

Management of Sacral Dimples in Neonates

The management of a sacral dimple in a 6-day-old neonate should be based primarily on its location along the craniocaudal axis, not on whether the base of the dimple can be visualized. 1

Assessment of Sacral Dimples

Location-Based Classification

• A dimple at or below an imaginary line drawn between the tops of the gluteal cleft (within the gluteal cleft) is considered a normal coccygeal dimple and requires no further workup or treatment 1
• A dimple located above this line (on the flat part of the sacrum) is considered a lumbosacral dermal sinus tract (DST) and requires further evaluation 1

Physical Examination Findings

• Examine for associated cutaneous manifestations that increase risk of spinal dysraphism:
  • Vascular anomalies (hemangiomas, capillary malformations) 1
  • Tufts of hair 1
  • Skin tags 1
  • Subcutaneous masses 1
• Assess the distance from the anus (dimples within 25mm of the anus on the median line are generally benign) 2
• Measure the size of the dimple (dimples less than 5mm are less concerning) 2

Diagnostic Approach

For Simple Coccygeal Dimples (Low Risk)

• If the dimple is located at or below the gluteal cleft line, within 25mm of the anus, measures less than 5mm, and has no associated cutaneous anomalies:
  • No imaging is necessary 1, 2
  • Parents can be reassured 2

For Lumbosacral Dimples or Those with Concerning Features (Higher Risk)

• If the dimple is located above the gluteal cleft line OR has associated cutaneous anomalies:
  • Spinal ultrasonography is recommended as the initial imaging study for infants under 6 months of age 1, 3
  • Consider consultation with a specialist (pediatric neurosurgeon) 2

Imaging Considerations

Ultrasonography

• Advantages:
  • Non-invasive and does not require sedation 1
  • Effective screening tool in infants younger than 6 months (before ossification of posterior elements) 3
• Findings that warrant further evaluation:
  • Conus medullaris terminating below the L2-L3 disc space 4
  • Decreased conus or nerve root motion 4
  • Abnormal filum terminale 4
  • Presence of an intraspinal mass 4
  • Osseous dysraphism 4
  • Sinus tract leading to the thecal sac 4

MRI

• Indicated when:
  • Ultrasonography reveals abnormal findings 4
  • High suspicion for spinal abnormalities despite normal ultrasonography 1
  • Associated markers of dysraphism (sacral dimple with skin appendage, tuft of hair, lipoma) 1
  • Bowel and bladder dysfunction or lower limb upper motor neuron signs 1

Clinical Significance and Outcomes

• The vast majority of isolated simple sacral dimples have benign outcomes:

  • Studies show only 0.13% of healthy infants with isolated simple sacral dimples required surgical intervention 4
  • Most abnormal ultrasound findings (low-lying conus, fatty filum) do not require surgical intervention 4

• Potential complications of untreated pathologic dermal sinus tracts include:

  • CNS infection (meningitis, intraspinal abscess) 1, 5
  • Aseptic meningitis 1
  • Spinal cord compression 1
  • Neurologic deterioration from tethering 1

Common Pitfalls to Avoid

• Do not rely on visibility of the base of the dimple to determine if it's pathologic - this is an outdated and incorrect approach 1
• Do not automatically order imaging for all sacral dimples - use the location and associated findings to guide decision-making 1, 2
• Do not delay evaluation of dimples with concerning features, as early treatment of dermal sinus tracts before infectious complications leads to better outcomes 2
• Avoid unnecessary imaging for simple coccygeal dimples, which can lead to healthcare costs and family stress 6