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Alpha Fetoprotein, Pregnant, Blood

AFP, MS-AFP, Alphafetoprotein, Maternal (MS), Alpha Fetoprotein (Maternal Serum)

Test Codes

Antrim #31371, EPIC: LAB5774, SOFT: AFPMA

Department

Special Chemistry

Instructions

Blood must be collected prior to amniocentesis.

Specimen Collection Criteria

Collect: One Gold-top SST tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

• Plasma specimens.
• Severely hemolyzed specimens.
• Severely icteric specimens.
• Severely lipemic specimens.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 0.5 mL)

Storage

Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers^® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers^® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 24 hours
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 1 year

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days

Laboratory

Royal Oak Special Testing Laboratory

Performed

Monday – Friday.
Results available within 2 business days.

Reference Range

Dependent upon gestational age.

Test Methodology

Chemiluminescent Immunoassay.

Interpretation

The optimal time for maternal screening is 16-18 weeks gestational age.

In addition to an open-neural tube defect, other pregnancy-related causes for increased serum AFP concentrations include miscalculated gestational age, multiple fetuses, fetal distress or death, fetal ventral wall defect, congenital nephrosis. Maternal liver disease may also cause an increased AFP level.

Because increased AFP levels have been reported in cases of normal unaffected pregnancies, other confirmatory test procedures are indicated.

Accurate determination of gestational age by ultrasonography is extremely important since the normal AFP levels change daily.

Clinical Utility

The AFP MoM is used to calculate the risk of a fetus having an open neural tube defect. Although screening for ONTD can be performed between 15 and 22 weeks of gestational age, the optimal time is between 16- and 18-weeks gestational age. The risk assessment given on the patients' report is a screen and not a diagnostic test. Abnormal results should be followed up by additional investigations. Neural tube defects result from the failure of the developing neural tube to fuse by the fifth week of gestation. In the U.S. approximately 2 infants in each 1000 live births will have this defect. Ninety-five percent of these births are to women with no history of an affected fetus.

Open neural tube defects (anencephaly and open spina bifida) occur with about the same frequency and account for 90% of all neural tube defects. Anencephaly is incompatible with life. Most fetuses spontaneously abort, are stillborn or die soon after birth. Impairments associated with spina bifida include: paralysis of the lower limbs, hydrocephalus, mental retardation, sensory loss, recurrent urinary tract infections, and bladder or bowel incontinence.

CPT Codes

82105

Contacts

Last Updated

12/29/2022