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HelpTest Code AFPA Alpha-Fetoprotein, Amniotic Fluid
Reporting Name
Alpha Fetoprotein, AFPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
Screening for open neural tube defects or other fetal abnormalities
Follow-up testing for patients with elevated serum alpha-fetoprotein results or in conjunction with cytogenetic testing
Method Name
AFPA: Immunoenzymatic Assay
ACHE_: Polyacrylamide Electrophoresis
Necessary Information
The following information is required:
1. Estimated due date by ultrasound
2. Collection date
3. Gestational age must be between 13 and 24 weeks; 16 to 18 weeks preferred.
If not ordering electronically, provide information on Second Trimester Maternal Screening Alpha-Fetoprotein / Quad Screen Patient Information (T595) and send with specimen.
Specimen Required
Container/Tube: Amniotic fluid container
Specimen Volume: 0.75 mL
Collection Instructions: Do not centrifuge.
Specimen Type
Amniotic FldSpecimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Amniotic Fld | Refrigerated (preferred) | 7 days | |
| Ambient | 7 days |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
< 2.0 multiples of median (MoM)
Interpretation
A screening alpha-fetoprotein (AFP) cutoff level of 2.0 multiples of median (MoM), followed by acetylcholinesterase (AChE) confirmatory testing on positive results, is capable of detecting 96% of open spina bifida cases with a false-positive rate of only 0.06% in non-blood-stained specimens.
AChE analysis is an essential confirmatory test for all amniotic fluid specimens with positive AFP results. Normal amniotic fluid does not contain AChE, unless contributed by the fetus as a result of open communication between fetal central nervous system (eg, open neural tube defects) or, to a lesser degree, fetal circulation. All amniotic fluid specimens testing positive for AFP will have the AChE test performed. False-positive AChE may occur from a bloody tap, which may cause both elevated AFP and AChE levels.
Day(s) Performed
Monday through Friday
Report Available
2 to 19 daysTest Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
82106
82013 (if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| AFPA | Alpha Fetoprotein, AF | 58735-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 6739 | Collection Date | 58734-5 |
| DAT15 | EDD by US Scan | 11781-2 |
| 6740 | Last Menstrual Period (LMP) | 8665-2 |
| 24233 | EDD by LMP | 11779-6 |
| 24239 | GA at Collection by Scan | 11888-5 |
| 24240 | GA at Collection by Dates | 11885-1 |
| 24234 | GA Used | 21299-3 |
| 9950 | Alpha Fetoprotein, AF | 1832-5 |
| 24241 | Results | 29595-6 |
| 24235 | Interpretation | 59462-2 |
| 24236 | Additional Comments | 48767-8 |
| 24237 | Follow up | 80615-8 |
| 24238 | General Test Info | 48767-8 |
Forms
Second Trimester Maternal Screening Alpha-Fetoprotein / Quad Screen Patient Information (T595) is required.
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| ACHE_ | Acetylcholinesterase, AF | Yes | No |
Testing Algorithm
If alpha-fetoprotein is positive, then acetylcholinesterase will be performed at an additional charge.