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Alpha-Fetoprotein (AFP), Amniotic Fluid

Published: August 9, 2026Updated: August 16, 2026

Measures the level of alpha-fetoprotein in amniotic fluid to help evaluate certain fetal conditions, especially open neural tube defects.

Quick summary

["Amniotic fluid AFP is one part of the evaluation for neural tube defects and is interpreted together with ultrasound and other prenatal test results."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
58735-2
Short code
AFP Pnl Amn
Synonyms
AFP Pnl Amn
Category
liver
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
0
Ref high
10
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82105
SNOMED
394971007
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What is this test?

Alpha-fetoprotein, or AFP, is a protein made by the developing fetus. This test measures AFP in the fluid surrounding the fetus, called amniotic fluid.

Why might I need this test?

This test may be performed after an amniocentesis to help evaluate the risk of open neural tube defects, such as spina bifida. It is usually interpreted with ultrasound findings and other laboratory tests rather than by itself.

How is the test performed?

A clinician collects a small amount of amniotic fluid during an amniocentesis procedure. The laboratory then measures the AFP concentration in that sample.

How do I prepare for the test?

Amniotic fluid AFP requires amniocentesis, so there is no separate preparation for the laboratory measurement. Your prenatal clinician will explain the procedure, its risks, and any instructions before it is performed.

Reference range

Normal: <10 ng/mLN/A

Specimen: serum

No special preparation required. For PSA, avoid sexual activity for 24-48 hours before the test.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Amniotic fluid AFP

Frequently asked questions

Does an abnormal AFP result mean the fetus has a neural tube defect?
No. An abnormal AFP result indicates that further evaluation may be needed, but it does not diagnose a condition by itself. The result is reviewed with ultrasound findings, pregnancy history, and other prenatal tests.
How is amniotic fluid AFP different from the maternal serum screening test?
The amniotic fluid test directly measures AFP in fluid surrounding the fetus. The maternal serum screening test measures AFP in the mother's blood and is part of a broader screening process.
Is amniocentesis done only for this test?
No. Amniotic fluid may also be tested for chromosomes, genetic conditions, or other markers. The clinician may recommend several tests using the same sample, depending on the pregnancy.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy