Also known as: Chromosome Studies, Karyotype (prenatal)« Back to test list
Chromosome analysis can detect balanced and unbalanced rearrangements, and numerical changes of autosomes and sex chromosomes. Chromosome studies of the parents may be necessary to clarify the genetic diagnosis and the risks to fetus.
An abnormal result usually provides a genetic diagnosis and the basis for genetic counselling. A normal result does not exclude a genetic or heritable abnormality as submicroscopic changes would not be detected.
This is an assay for heritable mutations. It may raise issues of ethics or consent that are different from most other investigations ordered in the routine care of a patient. The interpretation of the result may also be dependent on the family history and the interpretation of other studies.
Analysis of metaphase chromosomes by light microscopy. Chromosomes are counted, and examined for structural and numerical abnormalities.
This test is usually requested by an obstetrician or clinical geneticist.
Amniotic fluid or fetal blood sample is required. An invasive procedure by an obstetrician is necessary to obtain this.
To help ensure the quality of the test, a genetic test should be done with a dedicated sample whenever possible i.e. a sample collected specifically for that test rather than a sample that is used for multiple tests.
We also recommend that the patient or another adult check the labelling of request forms and sample tubes.