Karyotype Genetic Test
Reviewed
Also called: genetic testing, chromosome testing, chromosome studies, cytogenetic analysis
A karyotype test is a type of genetic testing. It looks at the size, shape, and number of chromosomes in a sample of cells from your body.
Specimen: For adults, children, and babies: blood (most common), buccal (cheek) swab, or bone marrow. For a fetus: amniotic fluid (amniocentesis) or chorionic villi (CVS).
Why this test may be ordered
- To check for chromosome problems in a fetus, especially if the pregnant parent is age 35 or older, if either parent has a genetic disorder or family history, or if prenatal screening results were not normal.
- To check yourself or family members for specific chromosome problems.
- To find out if abnormal chromosomes are causing infertility, frequent miscarriages, or stillbirths.
- To help diagnose and make treatment decisions for certain cancers and blood disorders such as leukemia, lymphoma, multiple myeloma, and anemia.
- To evaluate symptoms of a genetic disorder or to determine your risk if you have a family history of a chromosomal disorder.
Preparation and collection
What you have to do to prepare will depend on the type of test you're getting. For a CVS or amniocentesis, you may need to drink extra fluid and not urinate before your test so that your bladder is full. A blood test or cheek swab usually don't require any preparation. If you're having a bone marrow test, ask your provider for instructions about how to prepare.
For a karyotype test, the type of sample you provide depends on the reason for the test. A health care professional will take a blood sample from a vein in your arm, using a small needle. A health care professional will insert a swab into your mouth and rub it across the inside of your cheek to gather a sample of cells.
During amniocentesis or CVS, you may feel mild stinging or cramping. Both procedures are safe, but they do have a slight risk of causing miscarriage. Talk with your provider about the risks and benefits of these tests. A blood test has very little risk. A cheek swab has no risk. After a bone marrow test, you may feel stiff or sore where the sample was taken. Serious risks are rare.
Understanding results
Abnormal results can mean many things about your health or your child's health depending on the chromosome changes that were found.
- Normal (negative): A normal or negative result means that there were 46 chromosomes in the sample without any unusual changes in their structure. Limitation: Certain chromosome problems are present from birth, while others can develop in certain cells later in life. Next step: Talk with your provider to learn what your results mean.
- Abnormal (positive): An abnormal or positive result means that unusual changes in the number or structure of chromosomes were found. Limitation: But some changes in chromosomes don't cause problems. Next step: If you're thinking about having a karyotype test or have received abnormal results, it may help to talk with a genetic counselor.
- A normal result does not rule out all possible genetic or chromosome conditions.
- Additional testing may be needed to confirm the specific diagnosis and understand its implications.
- A blood test has very little risk; slight pain or bruising at the needle site, but symptoms usually go away quickly.
- A cheek swab has no risk.
- Amniocentesis and CVS are safe but have a slight risk of causing miscarriage.
What to do next
Talk with your provider to learn what your results mean. If you're thinking about having a karyotype test or have received abnormal results, it may help to talk with a genetic counselor.
- What does a normal result mean?
- What does an abnormal result mean?
- What specific chromosome changes were found in my sample?
- What health problems could these changes cause?
- Do I need further testing or a referral to a genetic counselor? What are my next steps?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.