Spina Bifida

Diagnosis

Symptoms

A pregnant woman has no symptoms to indicate her fetus has developed spina bifida. The appearance of a child born with spina bifida depends on the severity of the condition.

In spina bifida occulta, the mildest form, an abnormal tuft of hair, a collection of fat, a small dimple, or a birthmark, may be seen on the newborn's skin above the spinal defect and may be the only indication of the condition.

For meningocele and myelomeningocele, the more serious forms, a sac may protrude from the spinal cord on the newborn's back, or a section of spinal cord tissue may be exposed.

Other symptoms include bowel and bladder problems (i.e., constipation, incontinence), numbness below the area of the defect, and inability to move the lower legs (paralysis).

A child with spina bifida may also have other problems related to the condition, including hydrocephalus, heart problems, orthopedic (bone) problems and a lower-than-normal intelligence level.

Prenatal Screening

The doctor may suggest prenatal (before birth) screening tests to check for spina bifida. When spina bifida is diagnosed before birth, health care professionals can provide parents with information and support. They can plan for delivery in a specially equipped medical center so the baby can have any necessary surgery or treatment soon after birth.

Blood Tests

The primary test used to check for spina bifida is the maternal serum alpha-fetoprotein test (MSAFP). This test looks for alpha-fetoprotein (AFP), produced by the fetus. Abnormally high levels may indicate that the fetus has a neural tube defect, most commonly spina bifida or anencephaly, a condition characterized by an underdeveloped brain and an incomplete skull.

Because factors other than neural tube defects can cause varying levels of AFP — including a miscalculation in fetal age — the doctor may order a follow-up blood test for confirmation.

Often, doctors pair the MSAFP test with two or three other blood tests, which look for human chorionic gonadotropin (HCG), a hormone produced in the placenta, and estriol, an estrogen produced by both the fetus and the placenta. In addition to checking for neural tube defects, looking at these additional substances can help doctors determine whether chromosome abnormalities — such as Down syndrome — are present.

Ultrasound

Doctors may use ultrasound exams to help determine the cause of high AFP levels. An ultrasound exam bounces high-frequency sound waves off tissues in the body to form black and white images on a small video monitor. The information these images provide can help establish whether there's more than one fetus and can help confirm how long the mother has been pregnant, two factors that can raise AFP levels. With this diagnostic test, often the abnormality of the spinal cord and hydrocephalus can be detected.

Amniocentesis

If an ultrasound exam does not clarify the reason for the high levels of AFP, the doctor may suggest amniocentesis. During amniocentesis, the doctor inserts a needle into the amniotic sac that surrounds the fetus and removes samples of fluid.

A small amount of AFP is normally found in amniotic fluid. However, when an open neural tube defect is present, the amniotic fluid contains a large amount of AFP because the skin which normally surrounds the baby's spine is missing and AFP leaks into the amniotic sac. Although amniocentesis cannot indicate the severity of spina bifida, high levels of AFP may indicate the presence of spina bifida.