The karyotyping test is a laboratory diagnostic test used to examine the number, size, and structure of chromosomes in human cells. In this test, cells from a sample (usually blood, amniotic fluid, bone marrow, or tissue) are cultured in the laboratory and allowed to divide. When the cells reach metaphase, the chromosomes are stained, photographed under a microscope, and arranged in pairs according to their size and banding pattern to form a karyotype.

A normal human karyotype contains 46 chromosomes arranged in 23 pairs, including 22 pairs of autosomes and one pair of sex chromosomes (XX in females and XY in males). The karyotyping test helps identify chromosomal abnormalities, such as extra chromosomes, missing chromosomes, or structural changes.

This test is widely used for genetic diagnosis, prenatal testing, infertility investigations, and detection of chromosomal disorders such as Down syndrome, Turner syndrome, and Klinefelter syndrome.