The human body is full of minor, and often interesting, anatomical features. For those who notice small indentations on their lower back, the most common culprits are either Venus dimples or a sacral dimple. While most are harmless, understanding the distinctions can help determine if a medical check-up is ever needed, especially for newborns.
Dimples of Venus (or Apollo Holes)
Also known as 'back dimples' or 'lateral lumbar fossae' in anatomical terms, these are a pair of symmetrical indentations found on the lower back, just above the gluteal cleft. Named after Venus, the Roman goddess of beauty, they are considered by many to be an attractive physical trait. In males, they are sometimes called Apollo holes.
What Causes Venus Dimples?
Venus dimples are caused by a short ligament that stretches between the posterior superior iliac spine (the bony part of the pelvis) and the skin. This ligament pulls the skin inward, creating the indentation. They are a genetically predetermined feature, and while having less body fat can make them more visible, they cannot be created or enhanced through exercise alone.
Are Venus Dimples a Health Concern?
For the vast majority of people, Venus dimples are a harmless cosmetic feature with no medical implications. They do not indicate any underlying health issues. Some myths suggest they are a sign of good circulation or can affect sexual pleasure, but there is no medical evidence to support these claims.
The Sacral Dimple
A sacral dimple is a single indentation, or pit, found on the skin of the lower back, typically located just above the crease between the buttocks. Unlike Venus dimples, which are a pair, there is usually only one sacral dimple. Sacral dimples are a congenital condition, meaning a person is born with one.
When is a Sacral Dimple a Concern?
Most sacral dimples are simple, shallow, and harmless, requiring no treatment. However, in rare cases, they can be associated with a more serious underlying spinal problem. A healthcare provider will typically evaluate a newborn for any accompanying signs, which could indicate a spinal defect like tethered cord syndrome or spina bifida occulta.
Signs that may warrant further evaluation include:
- A deep dimple, where the bottom cannot be seen.
- A dimple located higher than the top of the buttock crease.
- A tuft of hair growing from or around the dimple.
- A skin tag, lump, or discoloration of the skin nearby.
What is the diagnosis process?
If a healthcare provider suspects an underlying issue, they may order non-invasive imaging tests to get a better look at the spine and spinal cord. These tests can include:
- Ultrasound: A safe and effective tool for screening newborns.
- Magnetic Resonance Imaging (MRI): Provides more detailed images for older infants or if the ultrasound is inconclusive.
Pilonidal Cyst vs. Sacral Dimple
A pilonidal cyst is sometimes confused with a sacral dimple, as it appears in the same general area, near the tailbone. However, there is a key difference: sacral dimples are present at birth, while pilonidal cysts develop after birth, typically in teenagers and young adults. A pilonidal cyst is a sac filled with hair and skin debris that can become infected and painful, whereas a sacral dimple is simply an indentation.
Comparison of Venus Dimples and Sacral Dimples
| Feature | Venus Dimples | Sacral Dimple |
|---|---|---|
| Appearance | Symmetrical pair of indents | Single indent or pit |
| Location | On either side of the spine, above the pelvic bone | Just above the crease of the buttocks |
| Cause | Genetic trait caused by short ligaments connecting skin to pelvic bone | Congenital formation during fetal development; cause not definitively known |
| Associated Concerns | None; purely cosmetic | Rarely, can indicate underlying spinal abnormalities |
| Associated Features | None | May be accompanied by a tuft of hair, skin tag, or discoloration in concerning cases |
| Visibility | Can become more visible with lower body fat | Does not change with body fat; may become less noticeable over time |
Conclusion
The indent on your back is most likely either a cosmetic Venus dimple or a harmless sacral dimple. In most cases, these indentations are no cause for alarm and require no medical intervention. It's the characteristics of the sacral dimple, particularly in infants, that warrant attention from a healthcare provider. With the majority of these features being benign, they are simply another unique aspect of human anatomy. To learn more about identifying concerning characteristics, consult reliable medical resources like the Mayo Clinic.
