First-trimester screening test for trisomy 21 (T21, Down syndrome) and trisomy 18 (T18). Requires nuchal translucency measurement performed by an ultrasonographer certified by the Fetal Medicine Foundation (FMF) or the Nuchal Translucency Quality Review (NTQR). Refer to Maternal Screening, Sequential, Specimen #2, Alpha Fetoprotein, hCG, Estriol, and Inhibin A (3000148) for second-trimester screening test for T21, T18, and open neural tube defects. Risks provided in both first and second trimesters.
Quantitative Chemiluminescent Immunoassay
Specimen must be drawn between 11 weeks, 0 days and 13 weeks, 6 days gestation. (Crown-Rump length (CRL) must be between 43-83.9 mm at time of specimen collection.)
Serum Separator Tube (SST) or Plain Red.
Separate from cells ASAP or within 2 hours of collection. Transfer 3 mL serum to an ARUP Standard Transport Tube. (Min: 1 mL)
Plasma. Hemolyzed specimens.
Submit with Order: Patient's date of birth, current weight, number of fetuses present, patient's race, if the patient was diabetic at the time of conception, if there is a known family history of neural tube defects, if the patient has had a previous pregnancy with a trisomy, if the patient is currently smoking, if the patient is taking valproic acid or carbamazepine (Tegretol), if this is a repeat sample, and the age of the egg donor if in vitro fertilization.
In addition to the above: the date of ultrasound, the CRL measurement, the nuchal translucency (NT) measurement and the name and certification number of the sonographer is required.
NT must be measured when the CRL is between 38-83.9 mm.
The NT measurement must also be performed by an ultrasonographer that is certified by one of the following agencies: Fetal Medicine Foundation (FMF) or Nuchal Translucency Quality Review (NTQR). To avoid possible test delays for an ultrasonographer that is new to our database, please contact the genetic counselor at (800) 242-2787 extension 2141 prior to sending specimen.
If an NT is unobtainable, order Maternal Serum Screening, Integrated (ARUP test codes 3000147 (collect in first trimester) and 3000149 (collect in second trimester)), which can be interpreted without an NT value.
After separation from cells: Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 year (Avoid repeated freeze/thaw cycles.)
Refer to report.
Laboratory Developed Test (LDT)
The first specimen of a Sequential Maternal Serum Screening is used to measure PAPP-A and hCG. This test is used to screen for fetal risk of Down syndrome (trisomy 21) and trisomy 18. Final interpretative report, which also includes fetal risk for Open Neural Tube Defect (ONTD), will be available when the second specimen test results are complete.
|Component Test Code*||Component Chart Name||LOINC|
|0080920||Maternal Screen Interpretation||49586-1|
|0080927||Number of Fetuses||11878-6|
|0080932||Maternal Age At Delivery||21612-7|
|0081065||Nuchal Translucency (NT)||12146-7|
|0081068||MoM for PAPP-A||32123-2|
|0081069||Sonographer Certification #||49089-6|
|0081074||MoM for NT||49035-9|
|0081158||Family History of Aneuploidy||32435-0|
|0081331||Best date to draw sample #2 by||33882-2|
|3000166||Crown Rump Length||11957-8|
|3000168||Nuchal Translucency (NT), Twin B|
|3000169||MoM for NT, Twin B||49035-9|
|3000170||Crown Rump Length, Twin B||11957-8|
|3000173||EER Maternal Serum, Sequential, Spcm1||11526-1|
|3000259||Patient's hCG, 1st Trimester||19080-1|
|3000260||hCG MoM, 1st Trimester||20465-1|
|3000263||Gestational Age Calculated at Collection||18185-9|
- first trimester screen
- Maternal Serum Sequential Screen
- Sequential Screening
- Serum Stepwise Sequential Screen
- Stepwise Maternal Screen
- Stepwise Sequential, Contingent