Neural Tube Defects: Risks, Symptoms, and Screening Options

Neural tube defects

Hello Dr.
Lu, I recently underwent a screening for Down syndrome, and the result was 1 in 1250.
However, the risk for "neural tube defects" was reported as 1 in 37.
The doctor suggested that to alleviate concerns, I should go to a larger hospital for a high-level ultrasound.
Later, when I visited another hospital and expressed my need for a high-level ultrasound, the doctor directed me to a room labeled for 4D ultrasound.
The detailed examination results showed that the brain, heart, and spine were all normal (at 20 weeks of gestation).
However, the doctor also informed me that the 1 in 37 statistic for neural tube defects could potentially be associated with other symptoms.
What might those symptoms be? Additionally, does the normal result from this examination mean everything is okay, or will further checks be necessary until delivery? Is the 1 in 37 risk for neural tube defects solely due to maternal folic acid deficiency? Thank you.

Danxin de Xiaoyu, 30~39 year old female. Ask Date: 2005/08/31

Dr. Lü Lizheng reply Obstetrics and Gynecology

The results of the 4D ultrasound examination indicate that the brain, heart, and spine are all normal at 20 weeks of gestation.
However, the physician informed that the risk of neural tube defects is 1 in 37, which may also be associated with other symptoms.
What could these potential symptoms be? [I am not aware of what symptoms of neural tube defects during fetal development entail and speculate that it may refer to the possibility of other neurological defects.
Please directly consult the physician for their expert opinion.] The physician mentioned that the risk of neural tube defects is significantly higher than the general population, yet stated that the brain, heart, and spine are normal.
They still recommend visiting a specialized medical center for a high-level ultrasound confirmation, as the facility labeled as a 4D ultrasound examination room may not necessarily perform advanced ultrasounds.
Sincerely, Lu Li-Cheng.

Reply Date: 2005/08/31

More Info

Neural tube defects (NTDs) are serious congenital conditions that arise when the neural tube, which eventually forms the brain and spinal cord, fails to close completely during early fetal development. Understanding the risks, symptoms, and screening options for NTDs is crucial for expectant parents, especially when faced with elevated risk ratios, such as the 1 in 37 statistic you mentioned.

Risks and Causes of Neural Tube Defects
The risk of NTDs can be influenced by several factors, including:
1. Folic Acid Deficiency: One of the most significant risk factors for NTDs is a lack of folic acid (vitamin B9) during pregnancy. Folic acid is essential for proper neural tube development. Women who are planning to become pregnant are advised to take folic acid supplements before conception and during the first trimester.

2. Genetic Factors: A family history of NTDs can increase the risk. Certain genetic mutations may also predispose individuals to these defects.

3. Maternal Health Conditions: Conditions such as diabetes, obesity, and certain medications (like anti-seizure drugs) can elevate the risk of NTDs.

4. Environmental Factors: Exposure to certain environmental toxins and substances during pregnancy may also contribute to the risk.

Symptoms of Neural Tube Defects
The symptoms of NTDs can vary widely depending on the type and severity of the defect. Common types include spina bifida and anencephaly. Symptoms may include:
- Spina Bifida: This condition can lead to physical disabilities, including weakness or paralysis in the legs, bladder and bowel control issues, and learning difficulties.

- Anencephaly: This is a more severe form where a major portion of the brain, skull, and scalp is absent. Infants born with anencephaly typically do not survive long after birth.

- Hydrocephalus: This condition, characterized by an accumulation of cerebrospinal fluid in the brain, can occur with spina bifida and may require surgical intervention.

Screening Options
Screening for NTDs typically involves:
1. Maternal Serum Alpha-Fetoprotein (MSAFP) Test: This blood test measures the level of alpha-fetoprotein in the mother’s blood. Elevated levels can indicate an increased risk for NTDs.

2. Ultrasound: High-resolution ultrasounds, including 4D ultrasounds, can help visualize the developing fetus and identify physical anomalies associated with NTDs.

3. Amniocentesis: In some cases, amniocentesis may be recommended to analyze the amniotic fluid for genetic abnormalities.

Follow-Up and Management
Given that your high-level ultrasound showed normal results for the brain, heart, and spine, this is a positive indication. However, the 1 in 37 risk ratio for NTDs suggests that while the current findings are reassuring, there remains a statistical risk that should not be dismissed.
It is essential to maintain regular prenatal care and follow-up with your healthcare provider. They may recommend additional ultrasounds or screenings as your pregnancy progresses, especially if any new symptoms arise or if there are concerns about fetal development.

Conclusion
In summary, while the current ultrasound results are normal, it is crucial to remain vigilant and continue discussions with your healthcare provider regarding any potential symptoms or concerns. The risk of NTDs is multifactorial, and while folic acid deficiency is a significant contributor, other factors may also play a role. Regular monitoring and open communication with your healthcare team will help ensure the best possible outcomes for you and your baby.

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