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HelpOrder Code LAB1STTM First Trimester Maternal Screen, Serum
Additional Codes
Mayo test Code: 1STT1
Ordering Guidance
This test does not screen for neural tube defects. If risk assessment for neural tube defects is desired, collect specimen between 15 weeks, 0 days and 22 weeks, 6 days of gestation for an alpha-fetoprotein single marker screen; order MAFP1 / Alpha-Fetoprotein (AFP), Single Marker Screen, Maternal, Serum.
QUAD screening (QUAD1 / Quad Screen [Second Trimester] Maternal, Serum) is not recommended following first-trimester screening.
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 link or complete the NT/CRL Data for First Trimester/Sequential Maternal Screening.
Specimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial within 2 hours of collection
Additional Information:
1. Blood draw and ultrasound must be completed between 10 weeks, 0 days and 13 weeks, 6 days of gestation, 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.
Forms
First Trimester/Sequential Maternal Screening Patient Information (T593) is required.
Useful For
Prenatal screening for trisomy 21 (Down syndrome) and trisomy 18
Special Instructions
Method Name
Immunoenzymatic Assay
Reporting Name
First Trimester Maternal ScreenSpecimen Type
SerumSpecimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 90 days | ||
| Ambient | 7 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
DOWN SYNDROME
Calculated screen risks <1/230 are reported as screen negative.
Risks ≥1/230 are reported as screen positive.
TRISOMY 18
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.
Method Description
The first-trimester screen for Down syndrome and trisomy 18 includes pregnancy-associated plasma protein A (PAPP-A), total human chorionic gonadotropin (hCG), and nuchal translucency measurement.
The Beckman Access HCG5 assay is an automated 2-site, mouse monoclonal antibody-based immunoenzymatic sandwich assay with paramagnetic separation and chemiluminescent detection. Testing is performed using the Beckman Coulter DxI.(Package insert: Access HCG5. Beckman Coulter, Inc; 2018)
The Access PAPP-A assay is a 2-site immunoenzymatic sandwich assay. Testing is performed using the Beckman Coulter DxI.(Unpublished Mayo method)
Day(s) Performed
Monday through Friday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
81508