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Chromosome Analysis and AFP, Amniotic Fluid

Code:10001|CPT:82106|LOINC:1832-5, 29253-2, 49051-6, 41273-4, 72486-4, 64095-3, 64096-1, 64092-0, 64091-2, 64093-8, 62356-1, 62357-9, 48002-0, 48672-0, 11502-2, 30106-9, 28067-7, 76479-5

Synonyms
АФП.AFPAFP, amniotic fluidAlpha-fetoprotein (AFP), amniotic fluidChromosome analysis and AFP, amniotic fluidKaryotype and AFP, amniotic fluid
IncludesAFP, Amniotic Fluid AFP Value AFP MoM Gestational Age(Wks) Interpretation Director Cells Counted Colonies Cells Analyzed Cells Karyotyped GTG Band Resolution Achieved Cytogenetic Diagnosis Cytogenetic Interpretation Specimen Type Director Review: PDF

Analysis details

Methodology

  • In situ culture of amniocytes with GTG banding
  • Sandwich immunoassay

Expected Turnaround Time

1 day

Special Instructions

  • Record the gestational age in weeks on the requisition as of the specimen collection date.
  • Provide a gestational age within 12–24 weeks for AF‑AFP interpretation; acetylcholinesterase false‑positive and false‑negative rates are higher at <13 weeks or >24.9 weeks.
  • If noninvasive prenatal testing (NIPT) has already been completed, attach a copy of the report.

How to use

The Chromosome Analysis and AFP, Amniotic Fluid test (karyotype and AFP, amniotic fluid) supports prenatal assessment of fetuses at risk for chromosomal aneuploidy and structural rearrangements and evaluates open neural tube and ventral wall defects through AF‑AFP quantitation. When AF‑AFP is abnormal, reflex testing to acetylcholinesterase and fetal hemoglobin may be performed for confirmation. Accurate gestational age is required for valid AFP interpretation. Additional biochemical or molecular studies may be ordered and performed in parallel while amniocyte cultures are established and analyzed.

Limitations

Alpha‑fetoprotein is produced by the fetal yolk sac, liver, and gastrointestinal epithelium and serves a transport role analogous to albumin in the fetus. AF‑AFP levels change over gestation, with higher concentrations in fetal fluids early in pregnancy and a progressive rise in maternal serum beginning near 10 weeks; therefore, precise gestational dating is essential for interpretation. Amniotic fluid AFP functions as a nonspecific indicator of fetal condition and obstetric pathology. In conjunction with reflex assays such as acetylcholinesterase, AF‑AFP supports evaluation for open neural tube defects and ventral wall defects, while cytogenetic analysis addresses chromosomal aneuploidy and structural rearrangements.

Reference interval
MinMax
07
IndicationsEvaluation of pregnancy for suspected fetal structural anomalies and chromosomal disorders, Second‑trimester testing, approximately 15–21 weeks’ gestation, Use in pregnant individuals undergoing amniocentesis or early chorionic villus sampling

Possible Causes of Abnormal Results

Decreased levels

  • insulin-dependent diabetes mellitus

Specimen Requirements

SpecimenSerum
ContainerGold/Tiger Top (SST, Gel Separator)
Volume15 mL (min 10 mL)
Storage InstructionsRoom temperature

References

Nazarenko G I, Kishkun A. Clinical Evaluation of Laboratory Test Results. Moscow: Meditsina; 2000. p. 339.

Gabant P, Forrester L, Nichols J, et al. Alpha-fetoprotein, the major fetal serum protein, is not essential for embryonic development but is required for female fertility. Proc Natl Acad Sci U S A. 2002;99(20):12865-12870. PMID: 12297623.

Fischbach FT, Dunning MB. A Manual of Laboratory and Diagnostic Tests. 8th ed. Lippincott Williams & Wilkins; 2008.

Wilson D. McGraw-Hill Manual of Laboratory and Diagnostic Tests. 1st ed. McGraw-Hill; 2007:23-25.