First Trimester Screen With Nuchal Translucency

Also known as: First Trimester Screening, Combined Test

Clinical Use

Order Test

Use

Screening test in the first trimester of pregnancy for fetal Down syndrome and trisomy 18

Special Instructions

Not provided.

Limitations

This screening test can indicate the likelihood of Down syndrome and trisomy 18 but cannot diagnose these conditions. It does not screen for open neural tube defects, and a positive result suggests further diagnostic testing may be required. MS-AFP in the second trimester is recommended for ONTD screening.

Test Details

Methodology

Immunoassay (Chemiluminescent)

Biomarkers

Dimeric Inhibin A (DIA)

Analyte

DIA Value

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

hCG

Analyte

hCG Value

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Pregnancy-associated Plasma Protein A (PAPP-A)

Analyte

PAPP-A Value

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

48798-3 - 1st trimester maternal scn Pnl SerPl

Result Codes

50679-0 - 1st trimester scn+NT Patient-Imp
11957-8 - Fet CRL US.meas
34970-4 - US Date
49089-6 - Sonographer
18185-9 - GA
43993-5 - Age at delivery
21484-1 - Mother's race
29463-7 - Weight
11878-6 - # Fetuses US
12146-7 - Fet Nuchal fold Thickness US.meas
49035-9 - Fet Nuchal fold MoM Thickness US.meas
19080-1 - HCG SerPl-aCnc
32166-1 - HCG adj MoM SerPl
48407-1 - PAPP-A SerPl-mCnc
76348-2 - PAPP-A adj MoM SerPl
23883-2 - Inhibin A SerPl-mCnc
36904-1 - Inhibin A adj MoM SerPl
43995-0 - Ts 21 risk Fetus
49090-4 - Fet Ts 21 risk from Mat age
43994-3 - Ts 18 risk Fetus
47223-3 - Fet Ts 18 risk from Mat age
77202-0 - Laboratory comment Report
11502-2 - Laboratory report

Result Turnaround Time

2-5 days

Specimen

Serum

Volume

3 mL

Minimum Volume

1 mL

Container

Gel-barrier tube

Collection Instructions

Collect in serum separator tube with gel barrier. Allow blood to clot and avoid hemolysis. Centrifuge to separate serum from cells. Do not use pour-off tubes. Draw specimens before amniocentesis to avoid contamination.