Karyotype is a test to identify and evaluate
the size, shape, and number of
chromosomes in a sample of body cells. Extra or missing chromosomes, or abnormal positions of chromosome pieces, can cause problems with a person's
growth, development, and body functions.
You do not need to do anything before you have 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
Karyotype testing can be done using
almost any cell or tissue from the body. A karyotype test usually is done on a
blood sample taken from a vein. For testing during pregnancy, it may also be
done on a sample of
amniotic fluid or the
The health professional
drawing your blood will:
For this type of test,
cells are collected from the fetus using
chorionic villus sampling. For more information about
amniocentesis, see the topic Amniocentesis or
Chorionic Villus Sampling.
Bone marrow aspiration may be used for a karyotype test. For more information about
how this test is done, see the topic
Bone Marrow Aspiration and Biopsy.
You may feel nothing at
all from the needle puncture, or you may feel a brief sting or pinch as the
needle goes through the skin. Some people feel a stinging pain while the needle
is in the vein. But many people do not feel any pain, or have only minor
discomfort, once the needle is positioned in the vein. The amount of pain you
feel depends on the skill of the health professional drawing the blood, the
condition of your veins, and your sensitivity to pain.
There is very little chance of a problem from having a blood sample taken from a vein.
Karyotype is a test to identify and
evaluate the size, shape, and number of
chromosomes in a sample of body cells.
Results of a karyotype test are usually available within 1 to 2
If you are being treated for cancer, the results of a karyotype test may not be accurate. Chromosomes may be damaged by some types of cancer treatment.
Other Works ConsultedChernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby.Skirton H, Patch C (2009). Genetics for the Health Sciences: A Handbook for Clinical Healthcare, 2nd ed. Oxfordshire, UK: Scion Publishing.
November 29, 2012
Kathleen Romito, MD - Family Medicine & Siobhan M. Dolan, MD, MPH - Reproductive Genetics
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