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Test ID BLOD1288 First Trimester Maternal Screen

Reporting Name

First Trimester Maternal Screen

Useful For

Prenatal screening for Down syndrome (nuchal translucency, pregnancy-associated plasma protein A, human chorionic gonadotropin) and trisomy 18 (nuchal translucency, pregnancy-associated plasma protein A, human chorionic gonadotropin)

Performing Laboratory

Mayo Medical Laboratories in Rochester

Specimen Type


Specimen Required

Approval to send specimen for first-trimester screening is required and may take up to 5 business days to complete. Nuchal translucency (NT) measurements are only accepted from NT-certified sonographers. Do not send specimen to Mayo Medical Laboratories if the sonographer is not NT-certified or before completing the application process. See Maternal Screening: Sonographer Approval Process link or complete the NT/CRL Data for First Trimester/Sequential Maternal Screening form in Special Instructions.



Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 1 mL

Collection Instructions: Immediately spin down.

Additional Information:

1. Blood draw and ultrasound must be completed between 10 weeks, 0 days and 13 weeks, 6 days, which corresponds to a crown-rump length (CRL) range of 31 to 80 mm.

2. Initial or repeat testing is determined in the laboratory at the time of report and will be reported accordingly. To be considered a repeat test for the patient, the testing must be within the same pregnancy and trimester, with interpretable results for the same test and both tests are performed at Mayo Clinic.

Specimen Minimum Volume

0.75 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 7 days
  Frozen  90 days

Reference Values


Calculated screen risks <1/230 are reported as screen negative.

Risks ≥1/230 are reported as screen positive.



Calculated screen risks <1/100 are reported as screen negative.

Risks ≥1/100 are reported as screen positive. A numeric risk for trisomy 18 risk is provided with positive results on non-diabetic, non-twin pregnancies.


An interpretive report will be provided.

Day(s) and Time(s) Performed

Monday through Friday; 8 a.m.-4:30 p.m.

CPT Code Information

81508-Fetal congenital abnormalities, biochemical assays of two proteins (PAPP-A, hCG [any form]), utilizing maternal serum, algorithm reported as a risk score

LOINC Code Information

Test ID Test Order Name Order LOINC Value
1STT First Trimester Maternal Screen In Process


Result ID Test Result Name Result LOINC Value
26428 Recalculated Maternal Serum Screen 43995-0
26411 Collection Date 33882-2
26412 Maternal Birthdate 21112-8
26429 Calculated Age at EDD 43993-5
26413 Maternal Weight 29463-7
26880 Maternal Weight 29463-7
IDD_ Insulin dependent diabetes 44877-9
B_RCE Black race 21484-1
IVF IVF 47224-1
DT3 Scan Date 34970-4
NUMF Number of Fetuses 55281-0
CRL1 CRL Measure 1 11957-8
CRL2 CRL Measure 2 11957-8
CHOR Chorions In Process
26430 GA on Collection by U/S Scan 11888-5
NT_ NT 48803-1
NT_B NT Twin B 48803-1
26426 PAPP-A 32123-2
26427 THCG 19080-1
26434 Down Syndrome Screen Risk Estimate 43995-0
26435 Down Syndrome Maternal Age Risk 49090-4
26436 Trisomy 18 Screen Risk Estimate 43994-3
26437 Interpretation 59462-2
26438 Additional Comments 48767-8
26439 Recommended Follow Up 80615-8

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

Reject Due To


Mild OK; Gross reject


Mild OK; Gross OK





Method Name

Immunoenzymatic Assay

Testing Algorithm

See Prenatal Aneuploidy Screening and Diagnostic Testing Options in Special Instructions.


First Trimester/Sequential Maternal Screening Patient Information (T593) is required in Special Instructions.

Secondary ID