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. Also called pilonidal dimples, most sacral dimples are small and shallow. Sometimes, a sacral dimple may be accompanied by increased hair growth in this area.
Most of the time, sacral dimples are harmless and don’t require you or your child to receive treatment. Rarely, a sacral dimple may indicate a serious underlying abnormality of the spine or spinal cord.
To rule out an abnormality, your 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 or risk factors.
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 swelling, discoloration, drainage or tenderness, your infant may undergo imaging tests to rule out a more serious condition. This may include:
- Ultrasound. Also called sonography, ultrasound is a noninvasive procedure that uses high frequency sound waves to produce precise images of structures of the body.
- Magnetic resonance imaging (MRI). This technique uses a magnetic field and radio waves to create cross-sectional images of the body.
Rarely, as your child gets older (especially during adolescence and adulthood), the sacral dimple may become infected and form a cyst (pilonidal cyst). This is usually due to hair, oil secretion and friction in the area. If a cyst occurs, your child’s doctor may recommend surgery to drain or remove the cyst.
Treatment is unnecessary for a simple sacral dimple.
However, if the sacral dimple is deep (extending well below the surface of the skin) or it becomes infected, it may indicate another condition that requires treatment.
Rarely, a sacral dimple indicates a more serious condition, such as spina bifida, a serious birth defect that occurs when the tissue surrounding the developing spinal cord of a fetus doesn’t close properly. In these rare instances, treatment depends on the underlying cause and may include surgery to correct or minimize the problem.
Keep sacral dimples clean and free of debris through good hygiene, including regular bathing.