It is not possible to have a fetus at 16 weeks when the nasal bone is not seen and combined with a chromosomal abnormality, but it is possible to have a fetus if the chromosomes are normal. Nasal bone examination is one of the ultrasound soft indicators of early pregnancy screening and can be used to screen for the risk of fetal comorbidities with chromosomal disorders. When the ultrasound examination at 16 weeks of pregnancy suggests that the nasal bone is not seen may be due to the influence of fetal position or nasal bone dysplasia caused by the need to comply with the medical advice of amniocentesis and other prenatal diagnosis, when the results suggest that chromosomal normal can be, need to comply with the medical advice and then review. Fetal nasal bone ossifies through membranous osteogenesis at 9~11 weeks of gestation, and screening can be performed at 11~14 weeks of gestation. When the nasal bone is absent at 16 weeks of pregnancy, and the prenatal diagnosis suggests that the fetus has a chromosomal abnormality, the fetus is not allowed, and the pregnancy should be terminated according to the doctor’s advice. When the ultrasound examination at 16 weeks of pregnancy suggests that the nasal bone is not seen, further examination should be carried out under the guidance of the doctor in order to clarify the cause and timely treatment.