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

Container/Tube:

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.