The primary blood test used to screen for neural tube defects (NTDs) is one that measures the amount of alpha-fetoprotein (AFP) in your blood.
Understanding the Alpha-Fetoprotein (AFP) Blood Test
This specific blood test is a crucial screening tool during pregnancy to assess the risk of neural tube defects. Here's what you need to know:
- What it measures: The test measures the levels of alpha-fetoprotein (AFP), a protein produced by the developing fetus.
- When it's done: Your healthcare provider typically orders this screening test between the 16th and 18th week of pregnancy.
- What high levels indicate: A higher-than-normal amount of AFP in the pregnant person's blood is a key indicator. Elevated AFP levels are found in approximately 75% to 80% of pregnant individuals carrying a fetus with a neural tube defect.
- Purpose: It serves as a screening test to identify pregnancies that may be at an increased risk for NTDs, prompting further diagnostic evaluation. It's important to note that a high AFP level does not definitively diagnose an NTD but rather suggests the need for additional testing.
This screening helps healthcare providers identify individuals who might benefit from more in-depth diagnostic tests, such as a high-resolution ultrasound or amniocentesis, to confirm or rule out the presence of a neural tube defect.
