Includes AFP, unconjugated Estriol, hCG, Dimeric Inhibin A, and Maternal Risk Interpretation
Preferred Specimen(s) 3 mL serum
Instructions Order using special requisition. Room temperature specimens must be received within 48 hours of collection. The Maternal Serum Screen 4 (MSS4) test in pregnant women should be performed between 14.0 and 22.9 weeks gestational age, although the optimal period is 15-16 weeks. This time frame allows sufficient opportunity for further diagnostic studies if the initial MSS4 test results are abnormal. Specimens submitted before 14.0 weeks or after 22.9 weeks gestation cannot be properly evaluated for open neural tube defects, Down syndrome or Trisomy 18. A special requisition form designed to obtain patient data and the patient’s informed consent must be utilized when ordering the MSS4 test. Because MSS4 test results are influenced by certain patient characteristics, the following data must be provided with the specimen in order to permit accurate interpretation of results: date of collection, patient’s (maternal) date of birth, patient’s estimated date of delivery, patient’s weight, patient’s race, patient’s diabetic status (is patient insulin dependent prior to pregnancy), number of fetuses, and whether this is a repeat sample.
Transport Container Plastic screw-cap vial
Transport Temperature
- Ambient 3 days,
- Refrigerated (cold packs) 7 days
Reject Criteria
- Gross hemolysis
- Gross lipemia
- Grossly icteric
Methodology Chemiluminescence
Clinical Significance Maternal Serum Screen 4 is used for prenatal screening of Down syndrome (Trisomy 21), Trisomy 18 (Edwards syndrome), and open neural tube defects (ONTD). This profile includes alpha-fetaprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and inhibin A. Establishing risk for fetal Down syndrome, using the quad screen achieves a 70-75% detection rate with a 5% false positive rate. Screening for Trisomy 18 detects 60% of affected fetuses with a 0.2% false positive rate. MSAFP screening detects 88% of anencephaly and 79% of open spina bifida with a 3% false positive rate. Normal results do not ensure birth of a normal infant. In addition, 2-3% of newborns have some type of physical or mental defect, many of which may be undetectable with current prenatal diagnostic procedures.