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Test Code AFPMS Maternal Serum AFP

Specimen Required

1 mL serum

Specimen Minimum Volume

0.5 mL

Specimen Stability

Room temperature: 14 days: Refrigerated: 14 days: Frozen: 45 days

Rejection Due To

Grossly lipemic

Day(s) and Time(s) Performed


Method Name

Immunoassay (IA)


AFP, Maternal Risk Interpretation

Collection Container / Tube

Preferred: Gold SST Tube
Other Acceptable Container: Red Top Tube (no gel)

Transport / Storage Conditions

Room temperature

Special Instructions

Prenatal risk assessment for open neural tube defects (NTDs). 
For manual orders use "Maternal Serum Screen Requisition." 

The MSAFP test in pregnant women should be performed between 15.0 and 22.9 weeks gestational age, although the optimal period is 15.0-16.9 weeks. This time frame allows sufficient opportunity for further diagnostic studies if the initial MSAFP results are abnormal. Specimens submitted before 15.0 weeks or after 22.9 weeks gestation cannot be properly evaluated. Because MSAFP 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 (EDD), patient's weight (in lbs.), patient's race, patient diabetic status (is patient insulin-dependent prior to pregnancy), number of fetuses, and whether this is a repeat sample.

Reference Values

NTD              <2.50
IDD                <1.90
TWINS           <4.00
TWINS IDD    <3.50
TRIPLETS      <4.50

CPT Codes


Clinical Reference

Maternal serum alpha-fetoprotein (MSAFP) is used for prenatal screening. Maternal serum Alpha-Fetoprotein (AFP) elevation is associated with open neural tube defects, multiple gestation, placental anomalies, ventral abdominal wall defects, congenital nephrosis, and oligohydramnios. Follow-up for abnormal AFP results include genetic counseling, level II or III ultrasound examination and consideration of amniocentesis for chromosome and AFP analysis. MSAFP is not to be used as a screening test for chromosomal abnormalities.

Analytic Time

3-4 days

Alias/See Also

AFP,Alpha-Fetoprotein, Maternal Serum
Neural Tube Defect Screen
AFP Single Screen


This test is not available for California or New York patient testing. For New York patient testing use new test code 92788-Maternal Serum AFP (NY)


MSAFP results consistent with increased risk of NTD may be followed-up with appropriate diagnostic testing as detailed in the report. MSAFP does not screen for chromosomal abnormalities.