Sequential 2

CPT [MAAA: 81511] or 82105; 82677; 84702; 86336
Synonyms
  • AFP, Maternal
  • Down Syndrome

Test Details

Use

Screening test for open neural tube defects, Down syndrome, and trisomy 18

Special Instructions

For test inquiries, call CMBP genetic services at 800-345-4363. Patient must have submitted a previous specimen in the first trimester for the Sequential 1 test. Gestational age will be based on crown rump length provided with the first trimester specimen. Patient information may be provided to the laboratory using the Maternal Prenatal Screening test request form 0900. Testing is provided from 15.0 to 21.9 weeks of gestation.

Limitations

Sequential screening requires two specimens: one collected in the first trimester and one in the second trimester. This test number is for the second trimester portion of the test. This is a screening test. A positive result means that diagnostic testing may be offered to the pregnant woman to determine if a neural tube defect or chromosome abnormality is present.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Methodology

Chemiluminescent immunoassay

References

Wald NJ, Rudnicka AR, Bestwick JP. Sequential and contingent prenatal screening for Down syndrome. Prenat Diagn. 2006 Sep; 26(9):769-777.16821246

Specimen Requirements

Information on collection, storage, and volume

Specimen

Serum

Volume

5 mL

Minimum Volume

3 mL

Container

Gel-barrier tube

Storage Instructions

Room temperature

Causes for Rejection

Gross hemolysis; gross lipemia; quantity not sufficient for analysis; improper specimen type

Collection

Collect in serum separator tube with gel barrier. Allow blood to clot, avoiding hemolysis. Separate serum from cells by centrifugation. Transport spun tube to testing laboratory.

Pour-off is not advised. Maternal serum specimens must be drawn prior to amniocentesis to avoid contamination with fetal blood.