Diagnosing Spina Bifida in Infants

Introduction

In most cases, Spina bifida is diagnosed prenatally, or before birth. However, some mild cases may go unnoticed until after birth, or postnatal. Very mild cases, in which there are no symptoms, may never be detected. Spina Bifida is a neural tube defect that occurs in 1 out of 1000 newborns in the United States, and 1 out of 750 in Canada.

Main Digest

If your child was just diagnosed with Spina Bifida, your excitement about your new baby may turn into shock, frustration, or anger, not knowing why this could possibly happen to you.

Many Spina Bifida parents find that they are actually a chosen group, one that is capable of overcoming their challenges and can see the many blessings these children bring.

Spina Bifida is an embryo abnormality that is normally detected in the first trimester, as it can start in the first four weeks, before a woman even knows that she is pregnant. Spina Bifida is a neural tube defect that occurs in 1 out of 1000 newborns in the United States, and 1 out of 750 in Canada. For some unknown reason, the embryo's neural tube, (spine, brain and vertebral column) fails to develop properly, causing varying degree of permanent damage to any one of these areas.

In most cases, spina bifida is diagnosed prenatally, or before birth. However, some mild cases may go unnoticed until after birth, or post-natally. Very mild cases, in which there are no symptoms, may never be detected.

Prenatal Diagnosis

The most common screening methods used to look for spina bifida during pregnancy are second trimester maternal serum alpha fetoprotein (MSAFP) screening and fetal ultrasound. The MSAFP screen measures the level of a protein called alpha-fetoprotein (AFP), which is made naturally by the fetus and placenta. During pregnancy, a small amount of AFP normally crosses the placenta and enters the mother's bloodstream. But if abnormally high levels of this protein appear in the mother's bloodstream it may indicate that the fetus has a neural tube defect. The MSAFP test, however, is not specific for spina bifida, and the test cannot definitively determine that there is a problem with the fetus. If a high level of AFP is detected, the doctor may request additional testing, such as an ultrasound or amniocentesis to help determine the cause.

The second trimester MSAFP screen described above may be performed alone or as part of a larger, multiple-marker screen. Multiple-marker screens look not only for neural tube defects, but also for other birth defects, including Down syndrome and other chromosomal abnormalities. First trimester screens for chromosomal abnormalities also exist but signs of spina bifida are not evident until the second trimester when the MSAFP screening is performed.

Amniocentesis - an exam in which the doctor removes samples of fluid from the amniotic sac that surrounds the fetus - may also be used to diagnose spina bifida. Although amniocentesis cannot reveal the severity of spina bifida, finding high levels of AFP may indicate that the disorder is present.

Methods used to check for spina bifida during pregnancy:

Blood tests - The primary test used to check for myelomeningocele is the maternal serum alpha-fetoprotein (MSAFP) test. In this procedure, your doctor draws a blood sample to be sent to a laboratory, where it's tested for alpha fetoprotein (AFP), a protein that's produced by the fetus. It's normal for a small amount of AFP to cross the placenta and enter the mother's bloodstream, but abnormally high levels of AFP may indicate that the fetus has a neural tube defect. Varying levels of AFP can be caused by factors including a miscalculation in fetal age or multiple fetuses. If this occurs, your doctor may order a follow-up blood test for confirmation. If the results are still high, you will need further evaluation, including an ultrasound examination.

Amniocentesis - If a blood test shows high levels of AFP in your blood and the ultrasound is normal, your doctor may offer an amniocentesis. During an amniocentesis, your doctor uses a needle to remove samples of fluid from the amniotic sac that surrounds the fetus. The analysis indicates the level of AFP present in the amniotic fluid. A small amount of AFP is normally found in amniotic fluid, however the amniotic fluid contains an elevated amount of AFP when an open neural tube defect is present because the skin surrounding the baby's spine is gone and AFP leaks into the amniotic sac. A second test can be done on the same sample to confirm that a neural tube defect is present. However, an amniocentesis cannot indicate the severity of spina bifida. This test does have a risk to the developing fetus - about one in 200 to one in 500 pregnant women miscarries after an amniocentesis.

Ultrasound - Many obstetricians use ultrasonography to screen for spina bifida. If blood tests indicate high AFP levels, your doctor will suggest an ultrasound exam to determine why. Ultrasound exams bounce high-frequency sound waves off tissues in your body to form black and white images on a small video monitor. The information these images provide can help establish whether there is more than one fetus and can help confirm gestational age - factors that can alter AFP levels. An advanced ultrasound can also detect signs of spina bifida, such as an open spine or particular features in your baby's brain that may indicate spina bifida. Ultrasound today is quite effective in detecting spina bifida and assessing its severity. This procedure is safe for both mother and baby.

Postnatal Diagnosis

Mild cases of spina bifida not diagnosed during prenatal testing may be detected post-natally by X-ray during a routine examination. Doctors may use magnetic resonance imaging (MRI) or a computed tomography (CT) scan to get a clearer view of the spine and vertebrae. Individuals with the more severe forms of spina bifida often have muscle weakness in their feet, hips, and legs. If hydrocephalus is suspected, the doctor may request a CT scan and/or X-ray of the skull to look for extra fluid inside the brain.Your child may develop hydrocephalus and may need to have a shunt placed as well. Hydrocephalus is having too much fluid in the brains ventricles. Your neurosurgeon will watch carefully for signs of hydrocephalus developing. It is very common for children with Spina Bifida to also have hydrocephalus.

Within the first 24 hours of life, surgery will be performed to close the opening to the spine. This can be a hard part for many parents because they just want to hold their baby and comfort it. It is a natural bonding period they are looking forward to; yet, the baby is normally put into surgery, almost immediately. Babies recover with great speed from the closure surgery.

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Cite This Page (APA): Langtree, I. C. (2009, February 18 - Last revised: 2015, September 15). Diagnosing Spina Bifida in Infants. Disabled World. Retrieved September 15, 2024 from www.disabled-world.com/disability/types/spinal/spina-bifida/diagnosing-spina-bifida.php

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