Alternative Names culture-amniotic cells, cultures-amniotic fluid
Definition This test, performed upon a sample of the fluid surrounding the foetus in the uterus (the "amniotic fluid"), is designed to detect a number of disorders of the foetus.
How is the test performed? Amniocentesis requires obtaining a sample of the fluid surrounding the foetus from the uterus of the mother. First, the location of the foetus is determined by ultrasound. Next, the skin of the abdomen is cleaned with antiseptic. Then, a long, thin, hollow needle is passed through the abdomen and into the uterus. A small sample of amniotic fluid - usually averaging 1 ml per week of gestation - is removed from the sac (the "amniotic sac") surrounding the foetus.
What is involved in preparation for the test? Request specific instructions from your doctor.
What do the test results mean? In a normal foetus, no chromosomal defects will be seen, and the levels of alpha-fetoprotein and bilirubin will be normal.
The presence of abnormal chromosomes may indicate genetic abnormalities in the foetus such as Down's syndrome, anencephaly (incomplete brain formation), or spina bifida (an open spine). In addition, Rh incompatibility and lung maturity can be determined.
Cells retrieved from samples of amniotic fluid can be put through DNA testing, which can identify the following gene-based disorders: abetalipoproteinemia; acatalasemia; acyl-CoA oxidase deficiency; alpha-1-antitrypsin deficiency; alpha thalassaemia and beta thalassaemia; Bloom disease; Canavan disease; Duchenne muscular dystrophy; Fabry disease; familial dysautonomia; Farber disease; Fragile X syndrome; glucose-6-phosphate dehydrogenase (G6PD) deficiency; Gaucher disease; GM1 gangliosidosis; haemophilia; Hunter syndrome (MPS-2); Huntington chorea; Hurler syndrome; Krabbe disease; Lesch-Nyhan syndrome; maple syrup urine disease; Maroteaux-Lamy syndrome (MPS-6); metachromatic leukodystrophy; Morquio syndrome(MPS-4); mucolipidosis (ML-1, ML-2, ML-3, ML-4); Multiple sulphatase deficiency; Niemann-Pick disease; phenylketonuria; Pompe disease (GSD 2a); GSD3; GSD4; retinoblastoma; Sanfilippo syndrome (MPS-3); Scheie syndrome; sickle cell disease; Tay-Sachs; tyrosinemia type 1; Wolman disease; X-linked adrenoleukodystrophy.
Author: David T. Moran, MD Reviewer: HealthAnswers Australia Medical Review Panel Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia Last Updated: 1/10/2001 Contributors Potential conflict of interest information for reviewers available on request
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