Karyotyping is a test to examine chromosomes in a sample of cells. This test can help identify genetic problems as the cause of a disorder or disease.

How the Test is Performed?

The test can be performed on almost any tissue, including:

• Amniotic fluid

• Blood

• Bone marrow

• Tissue from the organ that develops during pregnancy to feed a growing baby (placenta)

To test amniotic fluid, an amniocentesis is done. 

The laboratory specialist uses a microscope to examine the size, shape, and number of chromosomes in the cell sample. The stained sample is photographed to show the arrangement of the chromosomes. This is called a karyotype. Certain problems can be identified through the number or arrangement of the chromosomes. Chromosomes contain thousands of genes that are stored in DNA, the basic genetic material.

Why the Test is Performed This test can?

 • Count the number of chromosomes

• Look for structural changes in chromosomes

 • On a couple that has a history of miscarriage

• To examine any child or baby who has unusual features or developmental delays

The bone marrow or blood test can be done to identify the Philadelphia chromosome, which is found in 85% of people with chronic myelogenous leukemia (CML). The amniotic fluid test is done to check a developing baby for chromosome problems.