ALPHA FETOPROTEIN - amniotic fluid

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Specimen: Amniotic fluid collected between 14 and 16 weeks gestation.

Method: Immunoassay.

Reference Interval: Dependent on method and related to period of gestation. Consult pathologist.

Application: Detection of neural tube defects and some other fetal abnormalities. The test is usually only done when there is a confirmed elevation of serum a-fetoprotein or an abnormal ultrasound.

Interpretation: Consult pathologist. High levels may be found in association with neural tube defects and other abnormalities eg exomphalos, oesophageal atresia, congenital nephrotic syndrome. High levels are also found if there is contamination of the amniotic fluid sample with fetal blood.

Reference: UK Collaborative Study Group. Lancet 1979; 2: 651-662.

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