A sacral dimple is an indentation in the lower back, present at birth, but sometimes not noticed until the infant’s 6 week check. Most are blind ending, just above or within the crease of the buttocks, and do not require investigation or treatment.
However, if referral is required please refer as soon as possible. Ultrasound is the initial investigation of choice, but after around 8 weeks of age (after ossification of the vertebral arches) an MRI is performed (either a feed-and-sleep, or with a general anaesthetic).
Refer if
- the base of the dimples cannot be visualised
- the dimple is >5mm in size
- the dimple is >2.5cm above the anal margin
- there are associated cutaneous marking, hairy patch, skin tag, or fatty lump
- there is a duplicated gluteal cleft
- there is more than one dimple
- the dimple lies outside the sacrococcygeal region
- there are any neurological abnormalities noted
The above may be associated with an underlying neurological problem, for example spinal dysraphism.