Spina bifida is a birth condition where the spine and spinal cord don’t close properly during early pregnancy. Understanding how this condition is identified—both before and after birth—can help families and healthcare teams provide the best possible care and support.

Introduction: Who Should Undergo Diagnostics

The journey of diagnosing spina bifida often begins long before a baby is born. Pregnant women typically receive screening tests during routine prenatal care to check for spina bifida and other developmental conditions. These screenings are part of standard pregnancy care, especially for women between 18 and 21 weeks of pregnancy, when many important details about the baby’s development can be observed. The testing process is designed to give expectant parents information early enough to understand what to expect and plan for their child’s care.

For babies and children who were not diagnosed before birth, certain physical signs may prompt doctors to recommend diagnostic tests. These signs can include a visible opening or unusual marking on the lower back, such as a hairy patch, dimple, dark spot, or swelling. In the mildest form of spina bifida, called spina bifida occulta (meaning “hidden” spina bifida), there may be no visible signs at all. Many people with this type only discover they have it accidentally during an X-ray or imaging test done for a completely different reason, sometimes not until late childhood or even adulthood.

Some children may show symptoms as they grow that suggest problems with the spine or nervous system. These can include back pain, leg weakness, trouble controlling their bladder or bowel, or changes in how they walk. When these symptoms appear or worsen as a child develops, doctors may recommend diagnostic imaging to check for complications like a tethered spinal cord, which happens when the spinal cord becomes attached to surrounding tissue and stretches as the child grows.

Diagnostic Methods During Pregnancy

The process of identifying spina bifida before birth involves a combination of blood tests and imaging techniques. These prenatal diagnostic methods allow healthcare teams to detect the condition early and help families prepare for what comes next.

Blood Tests for Screening

One of the first screening tools used during pregnancy is a blood test that measures a protein called alpha-fetoprotein, or AFP. This protein is naturally produced by the developing baby. A small amount of AFP normally crosses the placenta and enters the pregnant parent’s bloodstream. However, when there is an opening in the baby’s spine, higher than usual amounts of this protein may leak into the surrounding fluid and eventually into the mother’s blood.

The maternal serum alpha-fetoprotein test (MSAFP) checks the level of AFP in the mother’s blood. When the levels are unusually high, it may suggest that the baby has a neural tube defect like spina bifida. However, high AFP levels don’t always mean something is wrong. Many other factors can affect AFP levels, such as having more than one baby, or simply getting the timing of the pregnancy wrong. Because of this, high AFP results typically lead to more testing rather than a definitive diagnosis.

The MSAFP test is often part of a larger group of blood tests sometimes called the “quad screen,” which looks for multiple conditions. These additional blood tests help doctors screen for other developmental issues, such as Down syndrome, alongside spina bifida. If the results from these blood tests raise concerns, doctors usually recommend follow-up testing to confirm whether spina bifida is actually present.

Ultrasound Examination

Ultrasound is the most accurate way to diagnose spina bifida before a baby is born. During pregnancy, an ultrasound uses sound waves to create pictures of the baby inside the womb. This is a safe, painless procedure that doesn’t use radiation. Healthcare providers often perform a detailed ultrasound examination between 18 and 21 weeks of pregnancy as part of routine prenatal care. This mid-pregnancy scan, sometimes called an anomaly scan, checks the baby’s development in detail.

During the ultrasound, the technician and doctor carefully examine the baby’s spine, looking for any openings or abnormalities. In cases of open spina bifida, where part of the spinal cord is exposed, the defect is often clearly visible on the ultrasound image. The scan can show not only the presence of spina bifida but also its location on the spine and how severe it appears. The position and size of the opening can give doctors important clues about what challenges the baby might face after birth.

Ultrasound can also detect other conditions that commonly occur alongside spina bifida. For example, many babies with the most serious form of spina bifida also develop hydrocephalus, which means there is too much fluid building up in and around the brain. During the ultrasound, doctors can measure the size of the baby’s head and check the brain structures to see if fluid is accumulating.

Amniocentesis

In some cases, when blood tests or ultrasound results are unclear or concerning, doctors may recommend a procedure called amniocentesis. This test involves taking a small sample of the fluid that surrounds the baby in the womb, called amniotic fluid. The procedure is typically done after 15 weeks of pregnancy.

During amniocentesis, a doctor uses ultrasound guidance to insert a thin needle through the mother’s abdomen into the womb to collect a small amount of amniotic fluid. This fluid contains cells from the baby and can be tested to measure AFP levels directly. High levels of AFP in the amniotic fluid can confirm the presence of a neural tube defect. The test can also provide information about the baby’s chromosomes and genetic makeup, which helps doctors look for other conditions.

While amniocentesis provides very detailed information, it does carry a small risk of complications, including a slight chance of miscarriage. Because of this, it’s typically only recommended when other screening results suggest a higher risk or when parents want more definitive answers about their baby’s condition.

Diagnostic Methods After Birth

For babies born with visible signs of spina bifida, the diagnosis is often clear immediately after delivery. However, additional tests are still needed to understand the full extent of the condition and plan appropriate treatment.

Physical Examination

When a baby is born, doctors perform a thorough physical examination. In cases of open spina bifida, particularly myelomeningocele (the most severe type), there is usually a visible sac or opening on the baby’s back where the spinal cord and nerves are exposed. This sac may be covered by a thin layer of tissue or skin, or in some cases, the nerves and spinal tissue may be directly exposed. The location of this opening along the spine—whether it’s in the lower back, middle back, or higher up—gives doctors important information about what functions might be affected.

For babies with meningocele, there is also a visible fluid-filled sac pushing through the spine, but the spinal cord itself is usually not involved. In contrast, spina bifida occulta may show only subtle skin changes over the spine, like a small tuft of hair, a dimple, or a birthmark. Sometimes there are no external signs at all.

The doctor will also check the baby’s movements and reflexes. By testing how well the baby can move their legs and respond to touch, healthcare providers can get an initial sense of whether there is nerve damage and how much function the baby has in the lower part of their body.

Imaging Tests

After a baby with spina bifida is born, several imaging tests help doctors see the internal structures and understand the full scope of the condition. These tests create detailed pictures of the spine, spinal cord, and brain.

Ultrasound can be used in newborns to look at the spine and brain. Because babies’ bones are still soft and not fully formed, ultrasound waves can pass through more easily, providing clear images of the spinal cord and brain structures. Doctors can use ultrasound to check for hydrocephalus by looking at the fluid-filled spaces in the brain, called ventricles. If these spaces are enlarged, it suggests fluid is building up.

X-rays provide images of the bones of the spine, showing where vertebrae haven’t formed or closed properly. This is particularly useful for diagnosing spina bifida occulta, which may only be discovered when X-rays are taken for another reason, since the spinal cord and nerves are normal and there are no symptoms.

Computed tomography, or CT scan, uses X-rays to create detailed cross-sectional images of the body. CT scans can show the bones of the spine in great detail and help doctors see the exact shape and location of the defect. They can also show if there are any bone abnormalities or complications.

Magnetic resonance imaging, or MRI, is one of the most detailed imaging tests available. An MRI uses powerful magnets and radio waves to create very clear pictures of soft tissues like the spinal cord, nerves, and brain. This test doesn’t use radiation, making it safer for repeated use. MRI scans can show whether the spinal cord is tethered, whether there is hydrocephalus, and whether there are any other abnormalities in the brain or spine that need attention.

Assessment of Organ Function

Because spina bifida can affect more than just the spine, doctors perform additional tests to check how well other parts of the body are working. These assessments help create a complete picture of the baby’s health needs.

Bladder and kidney function is particularly important to monitor. Many babies with spina bifida have trouble controlling their bladder because the nerves that control this function are damaged. Ultrasound scans of the bladder and kidneys can show whether the baby is able to empty their bladder properly or whether urine is backing up into the kidneys, which can cause damage over time.

Doctors also monitor the baby’s head growth carefully. By measuring the circumference of the baby’s head at regular intervals and using ultrasound or other imaging, they can detect whether hydrocephalus is developing or worsening. This ongoing monitoring is essential because hydrocephalus can develop or change quickly in the first weeks and months of life.

A careful assessment of the baby’s leg movements and muscle strength helps doctors understand the level of paralysis or weakness. This information guides decisions about physical therapy, mobility aids, and other interventions the child may need as they grow.

Diagnostic Testing for Clinical Trial Enrollment

Clinical trials are research studies that test new treatments or approaches to managing spina bifida. When families consider enrolling their child in a clinical trial, additional diagnostic testing is often required to determine whether the child meets the specific criteria for that study.

Each clinical trial has its own set of entry requirements, called inclusion and exclusion criteria. These criteria ensure that the study includes participants who are most likely to benefit from the treatment being tested and whose results will provide meaningful scientific information. For spina bifida trials, these criteria might specify the type of spina bifida required, the age of participants, the level of the spine affected, or the presence or absence of other conditions like hydrocephalus.

To determine eligibility, researchers typically require documentation of the diagnosis through medical records and imaging studies. Participants may need recent MRI or CT scans showing the exact location and characteristics of the spinal defect. Blood tests might be needed to check overall health status, kidney function, or other markers relevant to the treatment being studied.

For trials testing surgical techniques or medical devices, detailed assessments of nerve function, muscle strength, and mobility may be required. Researchers might use standardized tests to measure how well a child can move, their bladder control, or their cognitive abilities. These baseline measurements allow researchers to track whether the treatment being tested leads to improvements over time.

Prenatal clinical trials, such as those studying fetal surgery to repair spina bifida before birth, have very specific requirements. Expectant mothers may need multiple ultrasounds to confirm the diagnosis, assess the size and location of the defect, and ensure there are no other complications that would make the experimental procedure unsafe. Amniocentesis might be required to gather additional information about the baby’s condition.