A sacral dimple is an indentation, present at birth, in the skin on the lower back. It's usually located just above the crease between the buttocks. Most sacral dimples are harmless and don't require any treatment.
Sacral dimples that are accompanied by a nearby tuft of hair, skin tag or certain types of skin discoloration are sometimes associated with a serious underlying abnormality of the spine or spinal cord. In these instances, your child's doctor may recommend an imaging test. If an abnormality is discovered, treatment depends on the underlying cause.
A sacral dimple consists of an indentation, or "pit," in the skin on the lower back, just above the crease between the buttocks.
A sacral dimple is a congenital condition, meaning it's present at birth. There are no known causes.
Rarely, sacral dimples are associated with a serious underlying abnormality of the spine or spinal cord. Examples include:
Spina bifida. A very mild form of this condition, called spina bifida occulta, occurs when the spine doesn't close properly around the spinal cord but the cord remains within the spinal canal. In most cases, spina bifida occulta causes no symptoms.
Tethered cord syndrome. The spinal cord normally hangs freely within the spinal canal. Tethered cord syndrome is a disorder that occurs when tissue attached to the spinal cord limits its movements. Signs and symptoms may include weakness or numbness in the legs and bladder or bowel incontinence.
The risks of these spinal problems increase if the sacral dimple is accompanied by a nearby tuft of hair, skin tag or certain types of skin discoloration.
Sacral dimples are present at birth and are evident during an infant's initial physical exam. In most cases, further testing is unnecessary. However, if the dimple is very large or is accompanied by a nearby tuft of hair, skin tag or certain types of skin discoloration, your doctor may suggest imaging tests to rule out spinal cord problems.
These tests may include:
Ultrasound. This noninvasive procedure uses high-frequency sound waves to produce images of structures of the body.
Magnetic resonance imaging (MRI). If more detail is needed, your doctor may recommend an MRI, which uses radio waves and a strong magnetic field to create cross-sectional images of the body.