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Test ID SEQA Sequential Maternal Screening, Part 1, Serum

Ordering Guidance

When part 1 is negative, part 2 must be completed in order to receive an interpretable result. If collecting a second-trimester specimen is expected to be difficult, order first-trimester screening instead (1STT1 / First Trimester Maternal Screen, Serum).


If a stand-alone neural tube defect risk assessment is desired, order MAFP1 / Alpha-Fetoprotein (AFP), Single Marker Screen, Maternal, Serum.

Additional Testing Requirements

Sequential maternal screening is a 2-part test that includes a first-trimester sample (this test) and a second-trimester sample (SEQB / Sequential Maternal Screening, Part 2, Serum).

Necessary Information

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 Clinic Laboratories if the sonographer is not NT-certified or before completing the application process. See Maternal Screening: Sonographer Approval Process. Complete the NT/CRL Data for First Trimester/Sequential Maternal Screening.

Specimen Required


Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL

Collection Instructions:

1. The ultrasound and blood draw must be completed within a gestational window of 10 weeks, 0 days and 13 weeks, 6 days, which corresponds to a crown-rump length range of 31 to 80 mm.

2. Centrifuge and aliquot serum into a plastic vial within 2 hours of collection.

Useful For

First-trimester prenatal screening for trisomy 21 (Down syndrome) and trisomy 18 (Edwards syndrome)

Testing Algorithm

Sequential maternal screening is a 2-step test, with first- and second-trimester components. It requires a nuchal translucency measurement and blood collection in the first trimester. If the result from part 1 indicates a risk for Down syndrome that is higher than the screen cutoff, the screen is completed, and a report is issued. If the results from part 1 are negative, an additional blood collection in the second trimester is required (SEQB / Sequential Maternal Screening, Part 2, Serum). If the second specimen is not received for sequential screening, the results are uninterpretable, and no maternal risk will be provided.


For additional information see Sequential Maternal Serum Screening Testing Algorithm.

Method Name

Immunoenzymatic Assay

Reporting Name

Sequential Maternal Screen, Part 1

Specimen Type


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

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

Reference Values

An interpretive report will be provided.

Day(s) Performed

Monday through Friday

Report Available

4 to 6 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

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 US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
SEQA Sequential Maternal Screen, Part 1 49086-2


Result ID Test Result Name Result LOINC Value
29451 Recalculated Maternal Serum Screen 43995-0
601802 Results Summary 50679-0
29469 Down Syndrome Screen Risk Estimate 43995-0
29470 Down Syndrome Maternal Age Risk 49090-4
29471 Trisomy 18 Screen Risk Estimate 43994-3
29468 PAPP-A 48407-1
601799 PAPP-A MoM 76348-2
NT1 NT 33069-6
601800 NT MoM 49035-9
NTTB1 NT Twin 33069-6
601801 NT Twin MoM 49035-9
29472 Interpretation 49586-1
29474 Recommended Follow Up 80615-8
29473 Additional Comments 48767-8
29452 Specimen Collection Date 33882-2
29453 Maternal Date of Birth 21112-8
29890 Calculated Age at EDD 43993-5
29454 Maternal Weight 29463-7
29455 Maternal Weight 29463-7
DIAB1 Insulin Dependent Diabetes 33248-6
RACE_ Patient Race 32624-9
SMKN2 Current cigarette smoking status 72166-2
SNDT1 Scan Date 34970-4
CRL1A CRL 11957-8
CRL2A CRL Twin 11957-8
29891 GA on Collection by U/S Scan 11888-5
FET1 Number of Fetuses 11878-6
CHOR1 Chorions 92568-5
IVF1 IVF 47224-1
PRHIX Prev Down (T21) / Trisomy Pregnancy 53826-4
PRNTA Prev Pregnancy w/ Neural Tube Defect 53827-2
PTNTA Patient or father of baby has a NTD 53827-2
INTL2 Initial or repeat testing 86955-2
SONOM Sonographer Name 49088-8
SNCD1 Sonographer Code No LOINC Needed
SONO1 Sonographer Reviewer ID 49089-6
DRPH2 Physician Phone Number 68340-9
29487 General Test Information 62364-5