From the Guidelines
The recommended work-up for a sacral dimple depends on its characteristics and associated findings, with simple dimples typically requiring no further evaluation, while atypical dimples may necessitate spinal ultrasound or MRI of the spine. For simple sacral dimples (less than 5 mm in diameter, visible base, located within 2.5 cm of the anal verge, and without other cutaneous markers), no further evaluation is typically needed, as they are often considered benign and not associated with underlying spinal abnormalities 1. However, for atypical sacral dimples (larger than 5 mm, located more than 2.5 cm above the anus, with an invisible base, or associated with other cutaneous markers like hair tufts, skin tags, or hemangiomas), further evaluation is recommended to rule out underlying spinal dysraphism, tethered cord, or other spinal abnormalities that could cause neurological problems if left undetected 1.
Some key points to consider in the work-up of a sacral dimple include:
- Location: Dimples located above an imaginary line between the tops of the 2 forks of the gluteal cleft are considered abnormal and may require further evaluation 1
- Size: Larger dimples (greater than 5 mm) may be more likely to be associated with underlying spinal abnormalities
- Associated cutaneous markers: The presence of hair tufts, skin tags, or hemangiomas may indicate an increased risk of underlying spinal dysraphism
- Age: Infants younger than 3-4 months may undergo spinal ultrasound, while older infants and children may require MRI of the spine 1
During physical examination, clinicians should also assess for neurological abnormalities, lower extremity asymmetry, and abnormal reflexes, which might indicate underlying spinal cord involvement 1. Ultimately, the goal of the work-up is to identify any potential underlying spinal abnormalities and provide appropriate management to prevent long-term neurological sequelae.
From the Research
Sacral Dimple Work-up
The recommended work-up for a sacral dimple involves a thorough physical examination and potentially imaging studies to rule out underlying spinal dysraphism.
- A simple sacral dimple is a common physical examination finding among newborns and is rarely associated with spinal dysraphism 2.
- However, the presence of a sacral dimple along with other skin signs, local infection, meningitis, abscess, or abnormal neurological examination may indicate a higher risk of spinal dysraphism 3, 4.
- Ultrasonography can be used as a screening tool for spinal dysraphism in newborns with sacral dimples, but it may lead to unnecessary healthcare costs and stress on families if used inappropriately 2.
- Magnetic resonance imaging (MRI) is a more definitive diagnostic tool for detecting spinal dysraphism and should be used in cases where ultrasonography is abnormal or there are features of neurological involvement 3, 4, 5.
Imaging Studies
- Ultrasonography can be used to evaluate the spinal cord and detect abnormalities such as spinal dysraphism, but it has limitations and may not detect all types of spinal lesions 5.
- MRI is a more sensitive and specific diagnostic tool for detecting spinal dysraphism and should be used in cases where ultrasonography is abnormal or there are features of neurological involvement 3, 4, 5.
- The presence of a simple sacral dimple alone is a negligible marker for occult neural pathology, while the presence of isolated dermal sinus or more than one cutaneous marker could be considered indicative of higher risk of spinal dysraphism 5.
Clinical Evaluation
- A thorough physical examination, including a neurological examination, is essential in evaluating a newborn with a sacral dimple 2, 3, 4.
- The presence of other skin signs, local infection, meningitis, abscess, or abnormal neurological examination may indicate a higher risk of spinal dysraphism 3, 4.
- The clinical evaluation should also include an assessment of the sacral dimple itself, including its size, location, and any associated skin signs or symptoms 2, 3, 4.