Chromosomes are the carriers of genetic information, and chromosome testing is mainly to check whether there are any chromosomal abnormalities or hereditary chromosomal diseases. Chromosome test refers to karyotype analysis, usually the male chromosome is 46xy, female chromosome is 46xx, through the analysis of chromosomes, can be used for paternity testing, but also can diagnose diseases, such as trisomy 21, male reproductive organ anomalies or congenital anomalies in females, and early detection of hereditary diseases, and so on. For adult chromosome testing, peripheral blood is usually taken for testing, and hair and nail testing is also available. For fetal chromosome testing, chorionic villi can be taken in early pregnancy, amniotic fluid in mid-pregnancy, and umbilical cord blood in late pregnancy. If the fetus has chromosomal abnormalities, there is a possibility of congenital diseases, which requires prenatal diagnosis by a doctor to further assess whether the fetus can be successfully retained, the prognosis and the adverse consequences, and the couple will consider on their own whether they want to retain the fetus or not. Before the physical examination, it is recommended to avoid eating and strenuous exercise from the night before after 9:00 p.m., maintain sufficient sleep time, avoid staying up late, women should avoid menstruation, and the diet of a few days before the physical examination should be based on light, do not eat too greasy.