Phenotypic screening for fetal chromosomal or structural abnormalities (first-trimester maternal serum screening)
This test measures specific substances in your blood during early pregnancy to help assess the risk of certain chromosomal or structural abnormalities in your baby.
["Early pregnancy screening helps identify potential risks for genetic conditions that may require further evaluation or specialized care."]
Key facts at a glance
- LOINC
- 64720-6
- Short code
- Father pregnancy times PhenX
- Synonyms
- Father pregnancy times PhenX
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Critical range
- 0.5 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- phenx
- CPT
- 86592
- 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
What This Test Measures
The test detects levels of proteins and other substances (such as PAPP-A and free β-hCG) in your blood. These markers can provide clues about your baby’s chromosomal health and potential risks for conditions like Down syndrome, Edwards syndrome, or Patau syndrome.
Why It’s Done During Pregnancy
This screening is typically performed between 10 and 14 weeks of pregnancy. It’s part of routine prenatal care and helps guide discussions about next steps, such as additional testing (e.g., nuchal translucency ultrasound or amniocentesis).
How the Test Works
A blood sample is taken from you, and the lab analyzes the substances in your serum. The results are compared to standard ranges to estimate risk levels for chromosomal abnormalities.
What the Results Mean
Results are usually reported as a risk percentage for specific conditions. A low risk means your baby is likely healthy, while a higher risk may prompt further diagnostic testing. Your healthcare provider will interpret the results in the context of your pregnancy history and other factors.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
First-trimester maternal serum screening
Frequently asked questions
Is this test covered by insurance?
What happens if my screening results are abnormal?
Can I choose not to have this screening?
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.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy