Karyotype is a test to identify and evaluate
the size, shape, and number of
chromosomes in a sample of body cells. Extra, missing,
or abnormal positions of chromosome pieces can cause problems with a person's
growth, development, and body functions.
Why It Is Done
- Determine whether the chromosomes of an adult
have an abnormality that can be passed on to a child.
whether a chromosome defect is preventing a woman from becoming pregnant or
- Determine whether a
chromosome defect is present in a
fetus. Karyotyping also may be done to determine
whether chromosomal problems may have caused a fetus to be
- Determine the cause of a baby's birth defects or
- Help determine the appropriate treatment for some types
- Identify the sex of a person by determining the presence
of the Y chromosome. This may be done when a newborn's sex is not clear.
How To Prepare
No special preparation is needed before
having this test.
Talk to your doctor about any concerns you have
about the need for the test, its risks, or how it will be done. To help you
understand the importance of this test, fill out the
medical test information form(What is a PDF document?).
Since the information obtained from
karyotyping can have a profound impact on your life, you may want to see a
doctor who specializes in genetics (geneticist) or a
genetic counselor. This type of counselor is trained
to help you understand what karyotype test results mean for you, such as your
risk for having a child with an inherited (genetic) condition like
Down syndrome. A genetic counselor can help you make
well-informed decisions. Ask to have
genetic counseling before making a decision about a