Sacral Dimple in Babies: What It Is and When to Worry

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026

Quick Answer

A sacral dimple is a small pit in the skin of a baby's lower back, just above the crease of the buttocks. About 2% to 4% of babies are born with one. Most are harmless and need no treatment. A doctor may order an ultrasound if the dimple is large, deep, far from the buttock crease, or has a hair tuft, skin tag, lump, or skin discoloration nearby.

• How common: about 2–4 in every 100 newborns

• Usually: harmless, with no symptoms and no treatment needed

• Often low-risk when: small (under 5 mm), close to the anus (within 2.5 cm), the bottom is visible, and it's the only skin finding

• Ask for a check if: it's large or deep, sits higher up the back, or has hair, a skin tag, a lump, a birthmark, or discoloration nearby

• Urgent care if: fluid or pus leaks from it, it looks red and swollen, or your baby has a fever

What Is a Sacral Dimple?

A sacral dimple is an indentation in the skin over the sacrum, the triangle-shaped bone at the base of the spine. It sits in the lower back, usually just above the crease between the buttocks.

Babies are born with it. It forms while the baby develops in the womb, and there is no known specific cause. Nothing the parents did or didn't do during pregnancy causes a simple sacral dimple.

In most babies, the dimple is just a skin feature, like a dimple in the cheek. It may stay for life without causing any problems.

Is a Sacral Dimple Serious?

Usually not. Most babies with a sacral dimple never have symptoms or complications.

In a small number of babies, a dimple can be a surface sign of a problem in the spine or spinal cord underneath. Doctors look for specific features to decide which dimples need a closer look.

How Do Doctors Tell a Simple Dimple From a Concerning One?

Doctors check the dimple's size, depth, position, and the skin around it.

Usually low-risk ("simple") dimple

• Less than 5 mm across

• Less than 2.5 cm from the anus

• In the buttock crease, in the midline

• You can see the bottom of the dimple

• Only one dimple, with normal skin around it

• Normal leg movement and feeling on the baby's exam

Features that may need testing

• Larger than 5 mm, or deep

• Higher up the back, above the buttock crease, or off to one side

• You can't see the bottom

• More than one dimple

• A hair tuft, skin tag, lump, birthmark, bruise-like color, or discoloration nearby

• Weak legs, foot differences, or other abnormal exam findings

A small, single dimple in the buttock crease with a visible bottom and normal skin around it is generally considered low-risk. Your baby's doctor makes the final decision after examining your baby.

What Problems Can a Sacral Dimple Be Linked To?

When a dimple has warning features, doctors want to rule out:

• Spina bifida occulta: a mild form of spina bifida where the bones of the spine don't close fully, but the spinal cord stays inside the spinal canal. Most cases cause no symptoms.

• Tethered spinal cord: tissue attaches to the spinal cord and limits its movement. As a child grows, this can stretch the cord and cause leg weakness or numbness and bladder or bowel control problems.

• Dermal sinus tract: a thin channel running from the skin down toward the spine. Because it can let germs travel inward, it can lead to infection.

These are uncommon. The purpose of checking is to find them early if they are there.

How Is a Sacral Dimple Checked?

1. Physical exam. The doctor looks at the dimple and the skin around it, and checks your baby's legs, feet, and reflexes.

2. Spinal ultrasound. If the dimple has warning features, an ultrasound is usually the first test in young babies. It is painless, uses no radiation, and works best in the first few months of life, before the bones of the spine harden.

3. MRI. Doctors may use an MRI if the ultrasound shows a problem, if the baby is older, or if the findings are strongly suspicious. Babies usually need medicine to keep them still during an MRI.

How Is a Sacral Dimple Treated?

A simple sacral dimple needs no treatment. You can bathe your baby and clean the area as you normally would during diaper changes.

If tests find a problem such as a tethered cord or a dermal sinus tract, your baby will be referred to a pediatric neurosurgeon, who will explain the options.

When Should You Call Your Baby's Doctor?

Call your baby's doctor if:

• The dimple looks large, deep, or far from the buttock crease

• You notice a tuft of hair, hairy patch, skin tag, lump, or birthmark near it

• The skin around it looks bruised or discolored

• You can't see the bottom of the dimple

Get Medical Care Right Away If:

• Fluid, pus, or blood leaks from the dimple

• The area becomes red, warm, or swollen

• Your baby has a fever, is unusually sleepy, or is feeding poorly

• Your baby's legs seem weak, or you notice changes in how your child pees or poops as they grow

What Is the Outlook?

The outlook is excellent for most babies. A simple sacral dimple doesn't affect growth, walking, or daily life. For the few babies who have a spinal problem, finding it early gives doctors the best chance to treat it before symptoms appear.

Questions to Bring to Your Baby's Doctor

Print or save these questions for your visit:

1. Does my baby's dimple look simple or does it have any warning features?

2. Does my baby need an ultrasound? If so, by what age?

3. Does the area need any special cleaning or care?

4. What signs should make me call you or go to the emergency room?

5. Will we need follow-up checks as my baby grows?

More Sacral Dimple Guides on Rinnit

• Identifying the "Red Flags" of the Sacral Dimple — When a Tiny Indentation Matters

• Sacral Dimple Observation Guide: Differentiating Simple Indentations from Complex Findings

• Pilonidal Cyst: Symptoms, Causes, and Treatment (a different condition near the tailbone, usually in teens and adults)

• For clinicians: Clinical Protocol for the Evaluation and Triage of Neonatal Sacral Dimples

• For clinicians: Clinical Communication Guide: Navigating Sacral Dimple Findings with Families

For Clinicians and Creators

Explaining newborn findings to parents? The Animated Medical Icons Toolkit for Healthcare Explainer Videos helps you build short, clear explainer videos for your clinic or social media.

Frequently Asked Questions

Will my baby's sacral dimple go away?

It may stay for life. A simple dimple is only a skin feature and doesn't need to go away to be harmless.

Does a sacral dimple mean my baby has spina bifida?

No. Most babies with a sacral dimple have a normal spine. Only dimples with warning features need tests to rule out a spinal problem.

Does my baby need an ultrasound for a sacral dimple?

Not always. Small, single dimples in the buttock crease with a visible bottom and normal skin around them usually don't need one. Your baby's doctor decides based on the exam.

How do I clean a sacral dimple?

Clean it during normal baths and diaper changes. Gently wipe away any stool and pat the area dry. Ask your doctor if your baby's dimple needs special care.

Can adults have a sacral dimple?

Yes. People born with a simple sacral dimple often keep it into adulthood without any problems.

References

• Sacral dimple: Symptoms and causes — Mayo Clinic

• Sacral dimple: Diagnosis and treatment — Mayo Clinic

• Sacral Dimple — Cleveland Clinic

• Does This Sacral Dimple Need to Be Evaluated? — PediatricEducation.org

This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Only your baby's doctor can decide whether a sacral dimple needs testing. If the dimple leaks fluid, looks infected, or your baby has a fever, seek medical care promptly.