The nasal bone of the fetus is not clearly visible during the ultrasound examination in the twelfth week of pregnancy, this is only a description for the image seen during this ultrasound examination, it does not indicate that there is something wrong with the development of the fetus, and should be analyzed in conjunction with the NT value of the possible problems. the NT value and the absence or underdevelopment of the nasal bone are the soft ultrasound indicators for chromosomal abnormality in mid-pregnancy, and the occurrence of abnormality should be paid attention. Pregnant women whose first ultrasound examination reveals that the fetal nasal bone does not show clearly are advised to relax, live a normal life, and wait for another ultrasound examination two weeks later to observe the development of the fetal nasal bone, as well as the development of other systems. If the fetal nasal bone is still not clearly visible, or if it is found to be accompanied by other abnormal results at the same time, it is necessary to consider the possibility of abnormal development of the fetus, and further examination is needed, which can be done by non-invasive DNA, and according to the results of the examination to decide the next step of the treatment plan.