Parents have been asking me about the tiny hole they sometimes find on the base of the lower back of their babies. Well, let me see if I can give a simple explanation about these things we call sacral dimples.
Dimples, or pits at the base of the tailbone, just above or in the buttock crease, occur in at least 2 to 3 percent of newborns. This tiny hole results during the closure of the lining around the spinal cord.
Usually these holes connect to nothing and are no problem whatsoever, but they can also represent a problem in the closing off of the spinal cord from the skin. This failure of the spinal cord to close can allow a channel to exist between the cord and the skin, which can predispose your child to an infection that tracks inward from the skin to the spinal cord.
How can you tell if there is a problem? If you can see the floor of the dimple, that usually means there is no ongoing connection, especially if your child has an otherwise normal neurologic exam. We call this a “simple” dimple.
If you can’t see the floor of the dimple; or if the dimple is higher up on the lower back and has near it, or over it, skin discoloration or a tuft of hair; or if your child’s neurologic exam shows any abnormality, such as leg weakness suggesting a problem with the spinal cord, your child’s physician will want to do some additional imaging studies. These studies might include an ultrasound or MRI to see if there is an open connection that requires surgical repair.
It is important not to have the baby’s bowel movements collect in the pit, so put a barrier ointment over the sacral dimple and keep it clean to prevent any risk of infection if there is the slightest chance of an open connection with the spinal cord.
Hopefully tips such as this one will not be the pits when it comes to telling the simple from the not-so-simple sacral dimple.
Dr. Lewis First is chief of Pediatrics at Vermont Children’s Hospital at Fletcher Allen Health Care and chair of the Department of Pediatrics at the University of Vermont College of Medicine.