Sign in →

Test Code AFPA Alpha-Fetoprotein, Amniotic Fluid

Reporting Name

Alpha Fetoprotein, AF

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

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.

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

Amniotic Fld


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 Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Amniotic Fld Refrigerated (preferred) 7 days
  Ambient  7 days

Reference Values

< 2.0 multiples of median (MoM)

Day(s) Performed

Monday through Friday

Test 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

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.

Clinical Reference

1. Clinical Laboratory Standards Institute (CLSI): Maternal Serum Screening: Approved Standard. 2nd ed. I/LA25-A2 CLSI; 2011

2. Cuckle H. Prenatal screening using maternal markers. J Clin Med. 2014;3(2):504-520. doi:10.3390/jcm3020504

3. Bernard JP, Cuckle HS, Bernard MA, Brochet C, Salomon LJ, Ville Y. Combined screening for open spina bifida at 11-13 weeks using fetal biparietal diameter and maternal serum markers. Am J Obstet Gynecol. 2013;209(3):223.e1-5

Report Available

2 to 19 days

Method Name

AFPA: Immunoenzymatic Assay
ACHE_: Polyacrylamide Electrophoresis