Sequential Integrated Screen, Part 1
Use
Sequential Integrated Screen, Part 1 combines first‑trimester markers including PAPP‑A, hCG, and nuchal translucency to assess risk of Down syndrome (trisomy 21) and trisomy 18 during early pregnancy (first trimester) ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/about-our-tests/womens-health/pregnancy-and-fertility/pregnant-patients/testing-for-each-trimester?utm_source=openai)).
Special Instructions
If Down syndrome and trisomy 18 risk result indicates "In Process", a second‑trimester sample (test code 16133) must be submitted to complete the test and obtain a final result ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/clinical-education-center/faq/faq89?utm_source=openai)). High‑risk results should prompt counseling and consideration of diagnostic testing or noninvasive prenatal screening ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/clinical-education-center/faq/faq89?utm_source=openai)).
Limitations
This is a screening, not a diagnostic test. Gestational age must be accurate—calculated from crown‑rump length or EDD. Changing gestational age outside ±7 days may require resampling. In twin gestations, trisomy 18 risk may not be reported; results reflect pseudo‑risk, not fetus‑specific risk ([questdiagnostics.com](https://www.questdiagnostics.com/healthcare-professionals/clinical-education-center/faq/faq89?utm_source=openai)).
Methodology
Immunoassay
Biomarkers
LOINC Codes
- 49090-4
- 11884-4
- 23841-0
- 21198-7
- 49586-1
- 43995-0
- 43994-3
- 48407-1
- 32123-2
Result Turnaround Time
8 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
Not provided
Minimum Volume
Not provided
Container
SST
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 28 days |
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