Having an ultrasound at 17+5 weeks of pregnancy where everything is normal is generally not related to a positive or negative amniocentesis, meaning that an abnormal result can occur with an amniocentesis. Pregnant women generally need amniocentesis in the case of advanced maternal age, the mother has given birth to a child with chromosomal abnormalities, the family has a genetic predisposition to disease, Down’s syndrome screening suggests a high risk, and ultrasound indicators appear abnormal. Pregnant women do ultrasound everything is normal, there must also be other abnormalities, only need to do amniocentesis, amniocentesis results may be normal or abnormal. Amniocentesis is mainly used to diagnose fetal chromosomal disorders, single-gene disorders and hereditary disorders, such as trisomy 21 and chromosomal microdeletion syndrome. After amniocentesis, you should pay attention to rest, and seek medical examination if there is any abnormality. During pregnancy, you should pay attention to regular labor and delivery checkups to observe the development of the fetus.