The Sacral Dimple and How It Affects Children

Sacral dimples can manifest as a simple indentation in the skin but some could also be due to developmental conditions. Today's article will explain them in detail along with their implications.

Written and verified by the doctor Leonardo Biolatto.

Last update: 27 May, 2022

Some babies have a small indentation, a dimple, in the lumbar region, also known as the sacral area. The sacrum is a bone located in this area.

The sacral dimple may be a simple pit that leads to no discomfort whatsoever. However, this indent sometimes connects to the spinal canal and can cause problems in the nervous system.

Today’s article will describe it in more detail and also discuss its treatment.

What’s a sacral dimple?

As mentioned above, a sacral dimple is a notch or indentation that appears in the lower back. It’s present from birth. It’s usually located just above the buttock crease.

Most dimples of this kind are harmless; however, a significant percentage is associated with spinal dysraphism. This refers to certain congenital anomalies that cause incomplete closure of certain structures, such as the spinal column, according to an article in Acta Pediátrica.

It’s a heterogeneous group of malformations that expose the neural tissue. The same study states that between 40 and 95% of babies with spinal dysraphism have some kind of skin disorder. It’s a sacral dimple in many of these cases.

Above all, assume the sacral dimple is serious if it’s close to a tuft of hair or there are color changes in the skin immediately near it. The problem is that there could be neurological, urinary, rectal, or even orthopedic problems in these cases due to the neural alteration. This is why it’s essential to be able to distinguish it and seek and treat it.

Types of sacral dimpling

A sacral dimple could be typical or atypical. It’s this simple distinction that makes it possible to tell the difference between a benign situation and something serious. A typical or simple sacral dimple is small and located in the crease between the buttocks.

These are usually less than 13/64 inches in diameter and are close to the edge of the anus. They’re quite frequent and don’t imply any risk of dysraphism. In fact, estimates indicate that almost 5% of healthy newborns have them.

In contrast, there are atypical dimples that are larger, over a 1/4 inch deep, and farther away from the anus. They could actually be located near the sides.

An atypical dimple is a risk factor for spinal dysraphism. In fact, there may be abnormal communication with the spinal canal when they’re too deep. The spinal canal is a sensitive structure through which numerous nerve fibers run.

Thus, this communication can lead to spinal and neurological damage. Also, this type of dimpling may be accompanied by changes in skin color, lumps, and there may even be areas with unusual hair growth.

The difference between a sacral dimple and a pilonidal cyst

A pilonidal cyst contains hair formations inside. As with the sacral dimple, it occurs in the intergluteal area, just above the buttocks.

What happens in the pilonidal cyst is that hair, cells, waste substances, and fluid accumulate, resulting in a collection. Also, it usually develops after birth, it’s more common in men, and often becomes infected. The result is severe pain and swelling.

Causes of sacral dimpling

The causes of sacral dimpling are yet to be identified but we know it’s congenital. This makes it possible to distinguish it from the pilonidal cyst, as we mentioned above.

Atypical dimples may be derived from this defect in the closure of the midline structures. However, we don’t know why it happens.

Symptoms and diagnosis

Generally, sacral dimpling is asymptomatic. This is because it’s just a dimple, a cutaneous alteration in the lower back.

However, atypical sacral dimples usually have symptoms that depend on whether it’s due to spinal dysraphism. A doctor must do a thorough physical examination to detect it.

They usually measure and check the characteristics of the dimple and must do a series of complementary tests if it’s too large or deep. The same applies if there are more dimples, if there’s discoloration of the skin, or if it’s too far from the anus.

According to a study published in Archives of Disease in Childhood, ultrasound is a method for studying dimpling. Estimates indicate a sixfold increase in the likelihood of a spinal problem when abnormalities are present.

Ultrasound is a preferred technique because it’s quick, safe, and inexpensive. However, there’s always the option of an MRI if there are any doubts about the diagnosis. This is because it’s a more precise study of the tissues.

Possible complications

Atypical dimples have more complications and may be related to spina bifida or tethered spinal cord syndrome, among other conditions.

Spina bifida is a congenital malformation. What happens is the neural tube doesn’t close properly. There are different types but the one related to the sacral dimple is Spina Bifida Occulta.

Its main characteristic is a small gap in the spine that appears because the spine hasn’t developed. It may be asymptomatic and is usually detected during adolescence or adulthood.

In contrast, tethered spinal cord syndrome occurs when there’s scar tissue anchoring the spinal cord. It can lead to urinary and fecal incontinence, weakness in the lower extremities, and even difficulty standing.

Treatment of sacral dimples

There’s no treatment for a simple sacral dimple, and none is needed. The only thing you need to do is keep dirt from accumulating in the area to prevent infections. This is because the dimple is too close to the anus and intestinal bacteria could contaminate it.

That is why it’s essential to properly clean this area of a baby, especially when you change their diapers. An atypical dimple may require treatment, depending on its seriousness.

The procedure depends on the stage of the sacral dimple

Ideally, all newborns should be thoroughly examined by a doctor and these should do a sacral dimple study if they find one. It consists of measuring the dimple along with other abnormalities.

The child should be in good health if everything else is normal and the sacral dimple is small. However, the baby will require a specialist if the dimple is atypical or there are other warning signs.

Doctors must examine a dimple closely to find out if there are any neurological alterations or developmental defects. Also, the best treatment for a given case must be considered depending on specific results.

Finally, keep in mind that most sacral dimples are harmless and a mere skin alteration. However, you must consult a physician and rule out a neurological problem.