What is a Sacral Dimple? Symptoms, Causes, & Treatment

A sacral dimple is a small indentation or pit in the skin at the base of your spine, right above your tailbone. Most sacral dimples are completely harmless and simply part of how some people are naturally formed.

These little dimples appear in about 3-8% of newborns and are usually discovered during routine baby checkups. While the vast majority cause no problems at all, understanding what they are can help put your mind at ease and know when to seek medical advice.

What is a sacral dimple?

A sacral dimple is a small depression in the skin located in the sacral area, which is the lower part of your back where your spine meets your tailbone. Think of it as a tiny pocket or indentation that forms during early development in the womb.

These dimples typically measure less than 5 millimeters across and appear as shallow depressions. Most are what doctors call "simple" sacral dimples, meaning they're shallow, small, and don't connect to anything deeper in your body.

You might also hear healthcare providers refer to them as sacral pits or pilonidal dimples, though these terms can sometimes describe slightly different conditions. The key thing to remember is that the overwhelming majority of sacral dimples are completely benign.

What are the symptoms of a sacral dimple?

Most sacral dimples don't cause any symptoms at all. You'll simply notice a small indentation in the skin, and that's typically the only sign.

However, there are some situations where you might notice additional signs that could indicate the dimple connects to deeper structures. Here's what to watch for:

• A tuft of hair growing from or around the dimple
• A skin tag or small growth near the dimple
• Redness or swelling around the area
• Any discharge or drainage from the dimple
• A bluish discoloration of the skin nearby
• The dimple appears unusually deep or large (larger than 5mm)
• The dimple is located higher up on the back, away from the tailbone area

These additional signs don't necessarily mean there's a serious problem, but they do suggest your doctor should take a closer look. Most of the time, even dimples with these features turn out to be harmless.

What are the types of sacral dimples?

Doctors typically classify sacral dimples into two main categories based on their characteristics and potential for complications.

Simple sacral dimples are the most common type and are considered low-risk. These dimples are small (less than 5mm), shallow, and located within 2.5 centimeters of the tailbone. They don't have any hair, skin tags, or other unusual features around them.

Complex sacral dimples have one or more features that make doctors want to investigate further. These might be larger than 5mm, located higher up on the back, or have associated features like hair tufts, skin tags, or unusual coloring. While most complex dimples are still harmless, they have a slightly higher chance of connecting to the spinal cord or surrounding structures.

There's also a rare type called a dermal sinus tract, which is essentially a tunnel that extends from the skin surface toward the spinal cord. This occurs in less than 1% of all sacral dimples but requires medical attention because it can potentially lead to infections.

What causes a sacral dimple?

Sacral dimples form during the very early stages of pregnancy when your baby's spine and nervous system are developing. This happens during the first few weeks after conception, often before you even know you're pregnant.

The process involves the neural tube, which is the structure that eventually becomes the spinal cord and brain. Sometimes, small variations in how this tube closes can result in a tiny indentation in the skin. Think of it like a minor variation in a complex construction project.

In most cases, there's no specific cause you can point to. It's not something you did or didn't do during pregnancy, and it's not related to your family history or lifestyle choices. It's simply a normal variation that occurs during development.

Very rarely, sacral dimples can be associated with conditions affecting spinal cord development, such as spina bifida occulta or tethered cord syndrome. However, these connections are uncommon and usually involve other symptoms or features beyond just the dimple itself.

When to see a doctor for a sacral dimple?

If you notice a sacral dimple in your newborn, it's worth mentioning to your pediatrician during your next visit, but it's rarely an emergency situation. Most pediatricians will spot these during routine newborn examinations.

You should contact your doctor sooner if you notice any of these concerning features:

• The dimple appears to be draining fluid or pus
• The area around the dimple becomes red, swollen, or warm to touch
• Your child develops signs of infection like fever
• The dimple seems to be getting deeper or larger over time
• You notice new neurological symptoms like weakness in the legs or changes in bowel or bladder function

For adults who have lived with a sacral dimple without problems, routine monitoring is usually sufficient. However, if you develop new symptoms like pain, drainage, or recurrent infections in the area, it's worth having it evaluated.

What are the risk factors for sacral dimples?

Sacral dimples don't have clear risk factors in the traditional sense because they're developmental variations that occur randomly during early pregnancy. However, there are some patterns doctors have observed.

They appear to be slightly more common in certain populations, though the differences are small. Some studies suggest they may be more frequent in people of European descent, but this finding isn't consistent across all research.

Gender doesn't seem to play a significant role, as sacral dimples occur about equally in boys and girls. Family history also doesn't appear to be a strong predictor, meaning having a sacral dimple doesn't significantly increase the chances of your children having one.

The timing of spinal development during pregnancy is the main factor, and this process is largely beyond anyone's control. The neural tube closes very early in pregnancy, typically by the 4th week, when many people don't even know they're pregnant yet.

What are the possible complications of sacral dimples?

The vast majority of sacral dimples never cause any complications throughout a person's entire life. However, it's helpful to understand the rare possibilities so you know what to watch for.

The most common complication, though still quite rare, is infection. This can happen if the dimple is deep enough to trap bacteria or if it connects to deeper structures. Signs would include redness, swelling, warmth, discharge, or fever.

In very rare cases, a sacral dimple might be connected to the spinal cord through what's called a dermal sinus tract. This occurs in less than 1% of cases but can potentially lead to serious infections like meningitis if bacteria travel up the tract. This is why doctors pay attention to certain warning signs.

Some extremely rare complications include:

• Tethered cord syndrome, where the spinal cord is abnormally attached and stretched
• Spinal cord cysts or tumors (dermoid or epidermoid cysts)
• Recurrent urinary tract infections if there are associated spinal abnormalities
• Chronic drainage or pilonidal disease in the sacral area

These complications are so uncommon that most people with sacral dimples will never experience any problems. The key is appropriate evaluation when the dimple is first discovered and staying alert to any new symptoms over time.

How is a sacral dimple diagnosed?

Diagnosing a sacral dimple usually starts with a simple physical examination. Your doctor will look at the dimple's size, depth, location, and any associated features like hair or skin tags.

For simple sacral dimples that are small, shallow, and close to the tailbone with no concerning features, no additional testing is typically needed. Your doctor can confidently reassure you that these are harmless based on the physical examination alone.

However, if your doctor notices any complex features, they might recommend an ultrasound of the area. This painless test can help determine if the dimple connects to deeper structures and whether the spinal cord appears normal.

In some cases, particularly if the ultrasound shows any abnormalities or if there are neurological symptoms, an MRI might be recommended. This provides detailed images of the spinal cord and surrounding structures. However, this level of testing is only needed in a small percentage of cases.

The timing of these tests often depends on your child's age. Ultrasounds work best in very young infants because their bones haven't fully hardened yet, making it easier to see the spinal structures.

What is the treatment for sacral dimples?

Most sacral dimples require no treatment at all. If your doctor determines it's a simple dimple with no concerning features, the recommendation is typically just to keep the area clean and monitor for any changes.

For dimples that show signs of infection, treatment focuses on clearing the infection with antibiotics and proper wound care. Your doctor will guide you through keeping the area clean and dry while the infection resolves.

In the rare cases where imaging reveals a connection to the spinal cord or other abnormalities, treatment depends on the specific findings. This might include:

• Surgical repair if there's a dermal sinus tract connecting to the spinal cord
• Neurosurgical consultation for any spinal cord abnormalities
• Regular monitoring with periodic imaging studies
• Physical therapy if there are any associated neurological issues

The good news is that even when treatment is needed, outcomes are generally very good, especially when issues are identified and addressed early. Most children go on to live completely normal, healthy lives.

How to care for a sacral dimple at home?

Caring for a simple sacral dimple at home is straightforward and involves basic hygiene practices. Keep the area clean during regular bathing, gently washing with mild soap and water.

Make sure to dry the area thoroughly after bathing, as moisture trapped in the dimple could potentially lead to skin irritation or infection. You can gently pat the area dry with a clean towel.

Watch for any changes in the dimple's appearance, such as redness, swelling, discharge, or new pain. While these changes are uncommon, catching them early makes treatment more straightforward if needed.

For infants and young children, regular diaper changes and good hygiene practices are especially important since the diaper area can harbor bacteria. Keep the dimple area clean and dry during diaper changes.

You don't need to apply any special creams or treatments to the dimple unless your doctor specifically recommends them. In fact, it's best to avoid putting anything into the dimple itself, as this could potentially introduce bacteria.

How should you prepare for your doctor appointment?

Before your appointment, take some time to observe the sacral dimple and note any details that might be helpful for your doctor. Look at its size, depth, and whether there are any associated features like hair or skin changes.

Write down any questions or concerns you have about the dimple. Common questions include whether it will cause problems later in life, whether it needs any treatment, and what signs to watch for at home.

If you have any photos of the dimple, especially if you've noticed changes over time, bring these along. Sometimes visual documentation can be helpful for your doctor's assessment.

Prepare a brief history of when you first noticed the dimple and whether there have been any associated symptoms like drainage, redness, or pain. For infants, note whether the dimple was present at birth or appeared later.

Don't hesitate to ask your doctor to explain anything you don't understand. Questions about long-term outlook, activity restrictions, and when to seek medical attention are all perfectly reasonable and important for your peace of mind.

What's the key takeaway about sacral dimples?

The most important thing to remember about sacral dimples is that the overwhelming majority are completely harmless and require no treatment. They're simply a normal variation in how some people are formed during development.

While it's natural to feel concerned when you first discover a sacral dimple, especially in a newborn, take comfort in knowing that millions of people live their entire lives with these dimples without ever experiencing any problems.

The key is having the dimple properly evaluated by a healthcare provider who can determine whether it's a simple, low-risk dimple or whether any additional monitoring might be needed. Once you have this reassurance, you can focus on enjoying life without worry.

Stay alert to any changes in the dimple's appearance or new symptoms, but don't let anxiety about rare complications overshadow the fact that serious problems are extremely uncommon. With appropriate medical guidance, you can feel confident about managing this condition.