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Karyotype Genetic Test
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Karyotype Genetic Test

A karyotype test examines the size, shape, and number of chromosomes in your cells to identify genetic disorders or chromosomal abnormalities.

What is a karyotype test?

A karyotype test is a form of genetic testing that analyzes the 46 chromosomes found in human cells. Chromosomes are "packages" of DNA that control how your body grows and functions. The test checks for:

  • Full sets of chromosomes: Having too many or too few can cause conditions like Down syndrome or Turner syndrome.
  • Structural changes: Broken, missing, or extra parts of chromosomes that may lead to various health issues.

What is it used for?

This test is used to:

  • Check family members for specific chromosome problems.
  • Screen a fetus for genetic disorders.
  • Investigate causes of infertility, repeated miscarriages, or stillbirths.
  • Diagnose and guide treatment for cancers and blood disorders like leukemia, lymphoma, and anemia.

Why do I need a karyotype test?

Common reasons for testing include planning for pregnancy or being pregnant, especially if the pregnant parent is 35 or older, or if there is a family history of genetic disorders. You may also need this test if you or your child exhibit symptoms of a genetic condition, or if you have been diagnosed with a cancer that involves chromosomal changes.

What happens during a karyotype test?

The sample type depends on the patient:

  • For a fetus: Samples are collected via amniocentesis (collecting amniotic fluid) or chorionic villus sampling (CVS) (collecting placental tissue).
  • For adults, children, and babies: Samples are typically obtained through a standard blood test, a buccal (cheek) swab, or a bone marrow test (for certain cancers).

Risks and Preparation

Preparation varies by test type; for example, amniocentesis and CVS require a full bladder. Blood tests and cheek swabs require no preparation. While blood tests and swabs are low-risk, amniocentesis and CVS carry a slight risk of miscarriage. Bone marrow tests may cause temporary soreness. Always discuss the risks and benefits of these procedures with your provider.

What do the results mean?

  • Normal/Negative: 46 chromosomes were found with no structural changes.
  • Abnormal/Positive: Unusual changes in the number or structure of chromosomes were identified.

Because abnormal results can have significant implications for your health or your child's health, it is recommended to speak with a genetic counselor to understand your results and discuss management options.

Frequently Asked Questions

Standard karyotype analysis typically takes two to three weeks because the cells must be grown in a laboratory culture before they can be examined. In urgent clinical situations, such as suspected acute leukemia, a rapid preliminary result may be available in a few days, but the full detailed report still requires the standard timeframe.
No, a standard karyotype test cannot detect single-gene mutations. It only identifies large-scale chromosomal abnormalities, such as missing, extra, or rearranged chromosomes. To diagnose single-gene disorders, specific molecular genetic testing or DNA sequencing is required.
For adults and children, the test is usually performed via a standard blood draw, which involves only minor discomfort similar to a routine blood test. For prenatal diagnosis, the sample is obtained through amniocentesis or chorionic villus sampling, which are invasive procedures that carry a small risk of complications but are generally well-tolerated.
karyotype looks at the overall structure and number of chromosomes under a microscope, detecting large deletions or duplications. A chromosomal microarray (CMA) provides a much higher resolution, allowing it to detect tiny missing or extra pieces of DNA that a standard karyotype might miss, making it more sensitive for certain developmental delays or congenital anomalies.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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