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Serum Integrated Screen, Part 1

Test code(s) 16165, 16973 (NY)

The serum integrated screening test provides a single risk assessment for Down syndrome and trisomy 18 in the second trimester after the second sample has been analyzed. To complete the test and obtain a final result, please submit a second trimester sample within the date range provided on the report.

The gestational age is calculated from the crown rump length (CRL) provided, using criteria from the Fetal Medicine Foundation. If the CRL is not provided, the gestational age is derived from the estimated date of delivery (EDD) and the collection date provided and is an exact calculation by calendar days. Gestational wheels may be inaccurate by several days or more.

Note that the gestational age is reported in decimal weeks. For example, 11 weeks 4 days is reported as 11.6 weeks.



  1. ACOG Committee on Practice Bulletins. ACOG Practice Bulletin No. 77: screening for fetal chromosomal abnormalities. Obstet Gynecol. 2007;109:217-227. 


This FAQ is provided for informational purposes only and is not intended as medical advice. A clinician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.

Document FAQS.91 Version: 1
Version 1 effective 11/24/2015 to present
Version 0 effective 03/06/2013 to 11/23/2015