Fetal Nuchal Fold Thickness Test
A prenatal ultrasound test that measures the thickness of the fluid-filled space at the back of your baby's neck, usually performed between 15 and 20 weeks of pregnancy, to screen for an increased risk of certain genetic conditions such as Down syndrome.
{"A safe, non-invasive ultrasound test performed during pregnancy","Measures fluid accumulation at the back of the baby's neck","Helps screen for genetic conditions like Down syndrome","Typically performed between 15-20 weeks of pregnancy","Results are reported as Multiple of the Median (MoM)"}
Key facts at a glance
- LOINC
- 49035-9
- Short code
- Fet Nuchal fold MoM Thickness US.meas
- Synonyms
- Fet Nuchal fold MoM Thickness US.meas
- Category
- cardiac
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Ref low
- 22
- Ref high
- 198
- Critical range
- — – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- us-measured
- CPT
- 82553
- 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 is this test?
The fetal nuchal fold thickness test is a specialized ultrasound examination that measures the thickness of the fluid-filled space at the back of your baby's neck. During fetal development, all babies have some fluid in this area. An increased amount of fluid may indicate a higher risk for certain genetic conditions, particularly Down syndrome (trisomy 21).
How is the test performed?
This test is performed using a standard ultrasound machine. A technician will apply a special gel on your abdomen and use a transducer to capture images of your baby. The procedure is painless and typically takes 15-30 minutes. No special preparation, such as fasting, is required.
What do the results mean?
Results are reported as a Multiple of the Median (MoM), which compares your baby's measurement to what is normal for babies at the same gestational age. A normal nuchal fold measurement is generally less than 6mm. A higher measurement may indicate an increased risk for chromosomal conditions, but it does not provide a definitive diagnosis. Further testing, such as amniocentesis or cell-free DNA testing, may be recommended if results are abnormal.
Reference range
Adult males: 22-198 U/L; Females: 22-198 U/LN/A
No special preparation required. Inform provider of any chest pain or symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
The nuchal fold thickness test is primarily used as a screening tool for Down syndrome (trisomy 21). It can also detect other chromosomal abnormalities such as trisomy 18 and trisomy 13. An increased nuchal fold measurement may also be associated with congenital heart defects. It's important to understand that this is a screening test, not a diagnostic test – an abnormal result means further testing is needed, but it does not confirm a specific condition.
Frequently asked questions
Is this test safe for my baby?
When is this test usually performed?
What happens if the results are abnormal?
Do I need to fast or prepare for this test?
Sources
- 1
- 2
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