Spina bifida looks different depending on its type, ranging from a small dimple or patch of hair on a newborn’s lower back to a visible fluid-filled sac with exposed nerve tissue. The mildest form may have no visible signs at all, while the most severe form is immediately apparent at birth. Here’s what each type looks like and what parents and caregivers can expect to see.
Spina Bifida Occulta: Subtle Skin Markers
Spina bifida occulta is the mildest form, and most people who have it never know. The word “occulta” means hidden, and in many cases there are zero outward signs. The gap in the vertebrae is small, the spinal cord stays in place, and the skin over the spine looks completely normal.
When visible clues do appear, they show up on the skin of the lower back, right over the affected vertebrae. These markers include:
- A sacral dimple: a small indentation near the base of the spine, slightly above the crease of the buttocks
- A tuft of hair: an isolated patch of coarse hair growing from the skin over the lower spine
- A skin tag or small lump
- A birthmark or discolored patch of skin
A sacral dimple on its own is usually harmless. It becomes more concerning when it appears alongside other markers, like a nearby tuft of hair, a skin tag, or a discolored area. That combination can signal a deeper spinal issue that needs imaging to rule out.
Meningocele: A Skin-Covered Sac
Meningocele is the next step up in severity. In this form, the protective membranes surrounding the spinal cord push through an opening in the vertebrae and form a visible, fluid-filled sac on the baby’s back. The sac contains cerebrospinal fluid, the clear liquid that normally cushions the brain and spinal cord.
The sac most commonly appears on the lower spine. In most cases of meningocele, skin covers the sac, giving it a rounded, balloon-like appearance beneath intact skin. It can range in size from a grape to something considerably larger. Because the spinal cord and nerves typically stay in their normal position (only the membranes push outward), this type usually causes fewer neurological problems than more severe forms. An open meningocele, where no skin covers the sac, is less common but does occur.
Myelomeningocele: Exposed Nerves and Tissue
Myelomeningocele is the most severe and most recognizable form of spina bifida. At birth, both the protective membranes and part of the spinal cord itself, along with spinal nerves, push through the opening in the spine and form a sac on the baby’s back. Tissues and nerves are usually exposed, meaning there is no skin covering them. The raw, reddish tissue is visible immediately after delivery.
Sometimes skin does partially cover the sac, but in the majority of cases, the neural tissue sits open to the air. The sac can appear anywhere along the spine, though the lower back (the lumbar and sacral region) is by far the most common location. The higher the defect sits on the spine, the more severe the complications tend to be, because more of the nerve pathways below that point are affected.
Because the nerves controlling the legs, bladder, and bowel originate in the lower spine, babies born with myelomeningocele often have visible differences in their lower limbs. Clubfoot, where one or both feet turn inward and downward, is common. The legs may appear thinner or show uneven muscle development compared to the rest of the body, reflecting nerve damage that limits movement and muscle growth below the level of the defect.
What It Looks Like on Prenatal Ultrasound
Many parents first “see” spina bifida not on their baby’s body but on a prenatal ultrasound screen. Open spina bifida produces recognizable changes in the shape of the fetal skull and brain that sonographers are trained to spot.
The two classic ultrasound signs have informal names. The “lemon sign” refers to the skull taking on a lemon-like shape, with the frontal bones pinching inward. The “banana sign” describes the cerebellum (a structure at the base of the brain) curving into a banana shape instead of its normal rounded form. A study in the American Journal of Obstetrics and Gynecology found the lemon sign in 98% of fetuses with open spina bifida at or before 24 weeks of pregnancy, though it becomes much less reliable later, appearing in only 13% after 24 weeks. Cerebellar abnormalities were present in 95% of cases regardless of gestational age.
On ultrasound, the spinal defect itself can appear as a cystic mass along the spine, sometimes with splaying of the vertebrae visible in cross-section.
What It Looks Like After Surgery
Myelomeningocele requires surgical closure, typically within 24 to 48 hours of birth (or in some cases, prenatally while the baby is still in the womb). After surgery, the open sac is no longer visible. What remains is a surgical scar on the lower back.
In the weeks following closure, a scar lesion develops at the site. By about two months after surgery, the wound has typically healed into a visible scar. The scar’s size and shape depend on how large the original defect was and whether surgeons needed to use skin flaps or grafts to close it. Over time, the scar flattens and fades but remains a permanent feature. Children who had prenatal repair (surgery performed before birth) tend to have a similar scar, though the healing process begins earlier.
For children with spina bifida occulta or closed meningocele that doesn’t require surgery, the external appearance may not change at all over time. The dimple, hair tuft, or birthmark simply remains as it was at birth.
Other Physical Signs to Know
Beyond the spine itself, spina bifida can produce visible differences elsewhere on the body, particularly in more severe cases. Hydrocephalus, a buildup of fluid in the brain, occurs in many children with myelomeningocele and can cause the head to appear larger than expected. This is often managed with a shunt (a thin tube placed under the skin to drain excess fluid), which may be visible as a slight ridge running behind the ear and down the neck.
Leg and foot differences are among the most noticeable long-term physical signs. Depending on where the spinal defect is located, children may use braces, walkers, or wheelchairs. Foot deformities like clubfoot are often corrected with casting or surgery early in life, but some asymmetry in leg size or muscle tone can persist. Skin on the legs and feet may be more prone to sores because reduced sensation means injuries go unnoticed.