Sequential Maternal Screening, Part 1, Serum
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
Sequential maternal screening is a 2-part test, with first- and second-trimester components. It requires a nuchal translucency (NT) measurement and blood draw in the first trimester. If the result from Part 1 indicates a risk for Down syndrome that is higher than the screen cutoff, the screen is completed and a report is issued. If Part 1 results are negative, an additional blood draw in the second trimester is required (see SEQF / Sequential Maternal Screening, Part 2, Serum). If the second specimen is not received for sequential screening, the results are uninterpretable and no maternal risk will be provided.
The following are available in Special Instructions:
-Sequential Maternal Serum Screening Testing Process
-Low-Risk Pregnancy: Aneuploidy Screening and Diagnostic Testing Options Algorithm
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Approval to send specimen for first-trimester screening is required and may take up to 5 business days to complete. Nuchal translucency (NT) measurements are only accepted from NT-certified sonographers. Do not send specimen to Mayo Medical Laboratories if the sonographer is not NT-certified or before completing the application process. See Maternal Screening: Sonographer Approval Process link or complete the NT/CRL Data for First Trimester/Sequential Maternal Screening form in Special Instructions.
When Part 1 is negative, Part 2 must be completed in order to receive an interpretable result. If collecting a second-trimester specimen is expected to be difficult, order first-trimester screening instead (see 1STT / First Trimester Maternal Screen).
The ultrasound and blood draw must be completed within a gestational window of 10 weeks, 0 days and 13 weeks, 6 days, which corresponds to a crown-rump length (CRL) range of 31 to 80 mm.
Preferred: Red top
Acceptable: Serum gel
Specimen Volume: 1 mL
Collection Instructions: Immediately spin down.
Forms: First Trimester/Sequential Maternal Screening Patient Information (T593) is required; in Special Instructions.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Mild OK; Gross reject
Mild OK; Gross OK
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
|Serum||Refrigerated (preferred)||7 days|