Amniocentesis is used to check whether the number and structure of fetal chromosomes are abnormal. There are only two diagnostic results for amniocentesis, one is that the fetal chromosomes are in a normal state, and the other is that the fetal chromosomes are abnormal. In theory, there are generally no errors in the diagnosis, but there are many influencing factors, such as the absence of fetal cell survival or chimerism, that could affect the diagnosis. Due to the low probability of occurrence, the accuracy of amniocentesis is high, reaching 99 percent. If the amniocentesis has been completed, the result of the amniocentesis is a chromosomal abnormality.