SequentialScreenSM is a two-part test that screens for fetal Down syndrome, trisomy 18 and open neural tube defects. Between 10 weeks / 3 days (10.4 weeks, CRL = 39-84 mm) and 13 weeks / 6 days (13.9 weeks, CRL = 84 mm), pregnancy-associated plasma protein (PAPP-A) and human chorionic gonadotropin (hCG) are measured in a maternal blood sample and combined with the nuchal translucency (NT) measurement. A report is issued based on these analyses. There are two patient groups: “screen positive” and “final results pending second trimester sample.” Those who are “screen positive” are given a recommendation for genetic counseling and diagnostic testing. However, most women receive a “final result pending second trimester sample” interpretation and are directed to come back between 15 weeks / 0 days (15 weeks) and 21 weeks / 6 days (21.9 weeks) for a second blood draw. Alpha-fetoprotein (AFP), hCG, unconjugated estriol (uE3) and dimeric Inhibin-A are measured. SequentialScreen combines these measurements with the NT and PAPP-A from the first trimester to provide a final risk assessment.
Screening test for Down syndrome, open neural tube defects, and trisomy 18
Whole blood, serum, or dried blood spot
2-3 mL serum (unhemolyzed); Fill a minimum of three circles completely with blood; 7 mL blood
Serum separator tube (SST); IG-provided filter paper/test requisition; blood in Serum separator tube (SST) or red-top tube
Avoid hemolysis. Send complete specimen in the original tube. Do not pour off.
Integrated Genetics will only accept NT measurements from sonographers who have been certified by the Fetal Medicine Foundation (FMF) or the Nuchal Translucency Quality Review Program (NTQR). Please submit certification information before sending specimens for SequentialScreen. Please contact our Client Services Department with any questions.
Causes for Rejection
Gross hemolysis; gross lipemia; quantity not sufficient for analysis; improper specimen type
Store at room temperature
SequentialScreen requires two specimens: one collected in the first trimester and one in the second trimester. This test number is for the first trimester portion of the test. Result interpretation for the first trimester portion will be provided only for screen-positive specimens. Result interpretation for all others will be provided only when the second trimester specimen is received and tested. 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.