What does the Down syndrome screening test check for, and is fasting required?
Jul 21, 2025
Source: Cainiu Health
Dr. Zhang Lu
Introduction
The Down syndrome screening does not require fasting. The Down syndrome screening typically checks for conditions such as trisomy 21, trisomy 18, open neural tube defects, alpha-fetoprotein, and human chorionic gonadotropin. Trisomy 21 screening assesses the risk of the fetus having trisomy 21 by analyzing relevant markers in combination with maternal age and other factors. This condition may lead to intellectual disabilities and other problems in the fetus.
Generally, fasting is not required before undergoing Down syndrome screening. This screening typically checks for Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), open neural tube defects, alpha-fetoprotein (AFP), and human chorionic gonadotropin (hCG). Detailed explanations are as follows:
1. Trisomy 21: By measuring specific markers and considering maternal age, the risk of fetal Trisomy 21 can be assessed. This condition may lead to intellectual disabilities and delayed growth and development in the fetus.
2. Trisomy 18: Screening helps determine the likelihood of fetal Trisomy 18. Infants with this condition often have severe organ malformations and poor survival rates. Early screening facilitates timely intervention.
3. Open Neural Tube Defects: Changes in specific blood markers help identify the presence of open neural tube defects such as spina bifida and anencephaly. These abnormalities significantly affect fetal health.
4. Alpha-Fetoprotein (AFP): The concentration of AFP in maternal blood is measured. This protein is produced by the fetal liver, and abnormal levels may indicate chromosomal abnormalities or neural tube defects in the fetus.
5. Human Chorionic Gonadotropin (hCG): The level of hCG in maternal blood is measured. This hormone is secreted by the placenta, and its concentration is associated with the risk of fetal chromosomal abnormalities, aiding in the interpretation of screening results.
When undergoing Down syndrome screening, it is important to attend a reputable medical facility for the examination at the scheduled time. Fasting is not required prior to the test. If the screening results are abnormal, further diagnostic tests should be conducted as advised by a physician to ensure timely understanding of the fetal condition.
