Sequential Integrated Screen, Part 1

Casandra

Casandra Test Code QD25761Version 1 (DRAFT)

Performing Lab

Lab Quest DiagnosticsLab Test ID 16131CPT Code 81508

Sequential Integrated Screen, Part 1

Clinical Use

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)).

Test Details