1STT - Performance: First Trimester Maternal Screen

Test Catalog

Test Name

Test ID: 1STT    
First Trimester Maternal Screen

Method Description Describes how the test is performed and provides a method-specific reference

The first-trimester screen for trisomy 21 and trisomy 18 includes pregnancy-associated plasma protein A (PAPP-A), total human chorionic gonadotropin (ThCG), and nuchal translucency measurement. Analyte values are compared to median values at a given gestational age and multiple of the median (MoM) results obtained. The MoM results are used in a multivariate algorithm that includes the mother's age to derive risk factors for Down syndrome and trisomy 18. An interpretive report is provided. The Beckman Access ThCG assay is an automated 2-site, mouse monoclonal antibody-based immunoenzymatic sandwich assay with paramagnetic separation and chemiluminescent detection. Testing is performed using the Beckman Coulter DxI. (Beckman Coulter Assay Manual, Access Total HCG, 2010). The Access PAPP-A (RUO) assay is a two-site immunoenzymatic sandwich assay. Testing is performed using the Beckman Coulter DxI. (Package insert: Beckman Coulter Access PAPP-A [RUO[, Beckman Coulter, Inc., Fullerton CA 2009)

PDF Report Indicates whether the report includes an additional document with charts, images or other enriched information


Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Monday through Friday; 5 a.m.-5 p.m.

Saturday; 6 a.m.-1 p.m.

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

Same day/1 day

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

12 months

Performing Laboratory Location The location of the laboratory that performs the test