Phenotypic screening for pregnancy-associated conditions (e.g., fetal chromosomal abnormalities) using maternal serum/plasma
This test checks for certain markers in your blood that may help identify potential pregnancy-related health concerns, such as risks for chromosomal issues in your baby.
["Early detection of possible genetic or chromosomal concerns during pregnancy."]
Key facts at a glance
- LOINC
- 64631-5
- Short code
- Try pregnancy currently PhenX
- Synonyms
- Try pregnancy currently 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
- 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
This test analyzes specific substances in your blood that are influenced by pregnancy. It may detect proteins or other biomarkers that can indicate whether there are elevated risks for conditions like Down syndrome, trisomy 18, or other chromosomal abnormalities in your baby. The test often includes qualitative screening for substances like **human chorionic gonadotropin (hCG)** or other pregnancy-specific proteins.
Why It’s Done During Pregnancy
Healthcare providers may recommend this test during early pregnancy (often between 10 and 14 weeks) to assess the likelihood of chromosomal abnormalities. It’s typically used as part of a combined screening process that includes ultrasound measurements.
How the Test Works
The test involves collecting a blood sample from you and analyzing it using immunoassay methods (such as chemiluminescent immunoassay or fluorescence immunoassay) to detect the presence or levels of specific biomarkers. Results are often reported as qualitative (present/absent) rather than quantitative measurements.
What the Results Mean
Results may be categorized as normal, elevated, or suggestive of increased risk. If your results indicate a higher risk, your healthcare provider may recommend further testing, such as amniocentesis or chorionic villus sampling (CVS), to get more detailed information about your baby’s health.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
While this test helps identify potential risks for chromosomal abnormalities, it is not a definitive diagnostic tool. It provides an estimated likelihood of certain conditions, which can guide further medical evaluation. False positives or negatives can occur, so results should always be interpreted in the context of your overall health and pregnancy history.
Short name
Pregnancy-associated phenotype screening
Frequently asked questions
When Might I Need This Test?
What Should I Expect Before or After the Test?
Are There Any Risks or Side Effects?
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