Quad Screen (Second Trimester) Maternal, Serum
Use
This test is used for prenatal screening to assess the risk of open neural tube defects (such as spina bifida), trisomy 21 (Down syndrome), and trisomy 18 (Edwards syndrome) in pregnancies. By measuring the levels of certain analytes in maternal serum that are produced by the fetus and placenta, the test provides a risk estimate. It does not diagnose these conditions but indicates if further evaluation is needed. The tested analytes, including alpha-fetoprotein (AFP), estriol, human chorionic gonadotropin (hCG), and inhibin A, are compared against median values to determine risk factors for specific conditions.
Special Instructions
The test requires specific order entry questions to be answered or required information to be submitted using the designated 'Second Trimester Maternal Screening Alpha-Fetoprotein/Quad Screen Patient Information' form. Collection should not occur post-amniocentesis, and centrifugation should happen within 2 hours followed by aliquoting into a plastic vial. Results are best interpreted with complete and accurate maternal demographic data. Repeat testing criteria are detailed, focusing on results within the same pregnancy and trimester.
Limitations
The test's accuracy is affected by several patient factors, such as race, maternal weight, smoking, multiple fetuses, insulin-dependent diabetes, and IVF pregnancies. Black mothers may have higher AFP levels, but a lower risk of NTD. Gestational age errors can result in false positives/negatives, making dating accuracy crucial. Valid AFP measurements cannot be made post-amniocentesis. In vitro conditions, such as antibody interferences, may cause misleading results. Results need careful clinical correlation, especially for screen-positive outputs indicating further diagnostic evaluations.
New York Approved
Methodology
Immunoassay (Immunoenzymatic Assay)
Biomarkers
LOINC Codes
- 48800-7
- 44877-9
- 47224-1
- 55281-0
- 43995-0
- 49090-4
- 43994-3
- 49092-0
- 48767-8
- 80615-8
- 62364-5
- 32399-8
- 33882-2
- 21112-8
- 43993-5
- 29463-7
- 83086-9
- 11781-2
- 11779-6
- 11888-5
- 11885-1
- 21299-3
- 83073-7
- 2250-9
- 2478-6
- 48803-1
- 23811-3
- 21264-7
- 23841-0
- 36904-1
- 21484-1
- 64234-8
- 92568-5
- 53826-4
- 53827-2
- 77202-0
- 68340-9
Result Turnaround Time
4-6 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.75 mL
Container
Plastic vial
Collection Instructions
Do not collect specimen after amniocentesis as this could affect results. Within 2 hours of collection, centrifuge and aliquot serum into a plastic vial.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 90 days |