What is a newborn delivered at 34 weeks gestation with a dimple in the lumbar area at increased risk of, given a normal examination of the base of the dimple?

From the Guidelines

A newborn delivered at 34 weeks gestation with a dimple in the lumbar area and a normal examination of the base of the dimple is at increased risk of spinal dysraphism, particularly if the dimple is located above an imaginary line between the tops of the 2 forks of the gluteal cleft 1. Given the location of the dimple in the lumbar area, it is essential to consider the possibility of spinal dysraphism, which can be associated with cutaneous markers such as sacral dimples.

• The presence of a dimple in the lumbar area, rather than the gluteal cleft, increases the risk of spinal dysraphism 1.
• A normal examination of the base of the dimple does not entirely rule out the risk of spinal dysraphism, but it does suggest that the dimple may be a coccygeal dimple, which is generally considered benign 1.
• However, the location of the dimple in the lumbar area, rather than the gluteal cleft, warrants further evaluation to rule out spinal dysraphism, particularly if there are any associated cutaneous markers such as vascular anomalies, tufts of hair, skin tags, or subcutaneous dermoid masses 1.
• In the absence of any associated cutaneous markers, the risk of spinal dysraphism is lower, but it is still essential to monitor the infant for any signs of neurologic deterioration or spinal cord compression 1.
• Regular follow-up care, including monitoring for signs of spinal dysraphism, such as neurologic deterioration or spinal cord compression, is crucial to ensure the infant's optimal outcome 1.

From the Research

Newborns with Sacral Dimples

A newborn delivered at 34 weeks gestation with a dimple in the lumbar area is at increased risk of:

• Spinal dysraphism, although the risk is low if the dimple is isolated and simple 2, 3, 4
• Tethered cord, with a frequency of 0.13% in healthy infants with simple sacral dimples 4
• Other spinal malformations, such as lipoma, dermal sinus tract, or intrathecal mass, although these are rare 2, 5

Diagnostic Yield of Ultrasound

The diagnostic yield of ultrasound in neonates with sacral dimples is:

• Low, with only 4% of cases showing abnormal findings 5
• Higher in cases with multiple cutaneous markers or other congenital abnormalities 2, 3
• Useful as a screening procedure to select patients for further evaluation with MRI 2, 6

Risk Factors

The following factors increase the risk of spinal dysraphism in newborns with sacral dimples:

• Presence of multiple cutaneous markers 2, 3
• Anorectal anomalies 5
• Maternal diabetes during pregnancy 5
• Abnormal ultrasound findings, such as a low conus or abnormal filum terminale 4