Fetal alpha-fetoprotein (AFP) measured in maternal serum/plasma
This test measures alpha-fetoprotein, a protein produced primarily by the fetal liver and yolk sac. It helps screen for certain birth defects, such as neural tube defects, and is often part of an early pregnancy evaluation.
["Early detection of potential birth defects through protein screening in pregnancy."]
Key facts at a glance
- LOINC
- 11818-2
- Short code
- Fet Abd Diam AP US.meas
- Synonyms
- Fet Abd Diam AP US.meas
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-measured
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why is this test done?
Your healthcare provider may recommend this test during the first trimester (around 14–20 weeks of pregnancy) to check for certain birth defects, such as spina bifida or other neural tube defects. It may also be used as part of a combined screening test to assess risks of chromosomal abnormalities like Down syndrome.
What does the test involve?
A blood sample is taken from your arm. The sample is sent to a lab where it is analyzed to measure the level of alpha-fetoprotein in your serum or plasma. The results help determine if further testing or monitoring is needed.
What might affect test results?
Several factors could influence AFP levels, including gestational age (how far along in pregnancy you are), smoking, maternal diet, or certain medical conditions. If you have any concerns, discuss them with your healthcare provider before the test.
What do the results mean?
AFP levels vary widely depending on pregnancy stage. Elevated levels may indicate an increased risk of neural tube defects, while lower-than-expected levels could suggest other conditions that require further evaluation. Your healthcare provider will interpret the results in the context of your pregnancy history and other tests.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical significance: AFP plays a critical role in prenatal screening. High levels may prompt additional diagnostic tests, such as amniocentesis or ultrasound, to further evaluate risks. Low levels may require further investigation to rule out other potential causes.
Short name
Maternal AFP screening
Frequently asked questions
When will I get my results, and what should I do next?
Is this test painful?
Can I eat or drink before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy