Karyotype testing
Informed by recognized medical guidance
Overview
Karyotype testing is a laboratory test that looks at your chromosomes — the structures inside your cells that carry your genes. It counts the number of chromosomes and checks for any large changes in their shape or structure. This test can help diagnose or rule out certain genetic conditions.
Key facts
- Karyotype testing is usually done on a blood sample, but sometimes cells from other tissues (like bone marrow) are used.
- Results typically take 7 to 14 days because the cells need to grow in a lab before the chromosomes can be examined.
- It can find extra or missing chromosomes, large deletions or duplications, and rearrangements — it does not look for small changes (like single gene mutations).
Karyotype testing is a standard procedure in genetics and is not considered rare. It is often used when a genetic condition is suspected, during pregnancy (amniocentesis or CVS), or in certain cancers.
Anyone may have a karyotype test ordered by their doctor if there are signs of a chromosomal condition. It is commonly used for babies with birth defects, children with developmental delays, women who have had repeated miscarriages, adults with infertility, and people with certain types of leukemia or lymphoma.