α-Fetoprotein (AFP), Amniotic Fluid

TEST: 002428
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CPT: 82106
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Synonyms

  • AFP, Amniotic Fluid
  • Alpha-Fetoprotein (AFP), Amniotic Fluid
  • Amniotic Fluid AFP

Test Includes

Measurement of amniotic fluid AFP. Samples with AFP values ≥2.0 MoM will reflex to detection of acetylcholinesterase and fetal hemoglobin.

Special Instructions

Include the gestational age by ultrasound and/or last menstrual period (LMP) on the request form on the date of draw of the sample. The patient's gestational age must be between 12 weeks and 24 weeks for interpretation of α-fetoprotein. Note that AChE false-positive and false-negative results are more frequent at gestational ages less than 13 weeks or greater than 24.9 weeks. Optimal gestational age is 14 to 18 weeks.

Expected Turnaround Time

2 - 5 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Specimen Requirements

Specimen

Amniotic fluid

Volume

1 mL

Container

Sterile plastic conical tube; do not use urine containers or tubes with rubber stoppers. Rubber is toxic to amniocytes.

Collection

Avoid contamination of amniotic fluid with maternal or fetal blood. As little as one drop of fetal blood can cause false-positive results during assay of amniotic fluid. Amniotic fluid should be collected by the attending physician.

Storage Instructions

Ship and maintain specimen at room temperature.

Patient Preparation

The patient should have undergone ultrasound studies to verify fetal viability, detect multiple gestation, confirm gestational age, localize placenta, and detect fetal and uterine pathology.

Causes for Rejection

Specimen not amniotic fluid; gross contamination of amniotic fluid with maternal or fetal blood; quantity not sufficient for analysis

Test Details

Use

Analysis of midtrimester amniotic fluid for detection of open neural tube defects and ventral wall defects

Limitations

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Methodology

Chemiluminescent immunoassay

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
002428 AFP, Amniotic Fluid 58735-2 010806 AFP, Amniotic Fluid N/A
002428 AFP, Amniotic Fluid 58735-2 101352 AFP Value ug/mL 1832-5
002428 AFP, Amniotic Fluid 58735-2 101360 AFP MoM 29253-2
002428 AFP, Amniotic Fluid 58735-2 101379 Gestational Age(Wks) 49051-6
002428 AFP, Amniotic Fluid 58735-2 101378 Interpretation 41273-4
002428 AFP, Amniotic Fluid 58735-2 101376 Director 72486-4
002428 AFP, Amniotic Fluid 58735-2 999500 Amniotic Fluid, AFP N/A
Reflex Table for Interpretation
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 510206 AChE+Hb F 510172 Acetylcholinesterase 30106-9
Reflex Table for Interpretation
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 510206 AChE+Hb F 510180 Fetal Hemoglobin 28067-7
Reflex Table for Interpretation
Order Code Order Name Result Code Result Name UofM Result LOINC
Reflex 1 510206 AChE+Hb F 510173 Interpretation 76479-5

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