There is no nasal bone at 13 weeks of pregnancy, it may grow out later, but there is a possibility of fetal malformation, it is best to go back to the hospital after one to two weeks for rechecking, if the nasal bone still can not be found, further screening should be carried out, and if it is considered to be a developmental abnormality of the fetus, it can be disposed of in accordance with the standardization of the medical advice, if necessary. At 13 weeks of pregnancy, if the fetus is not in a good position, you may not be able to see the face clearly in ultrasound, in this case, you can go back to the hospital in a week or two weeks for further screening to see the development of the nasal bone. In general, the absence of nasal bone mostly suggests chromosomal abnormality of the fetus, which is mostly seen in Down’s babies, i.e. Trisomy 21, manifested by mental retardation, developmental delay, organ malformation and so on. If the absence of nasal bone is detected by NT screening and the nasal bone is still missing after retesting, it is necessary to do non-invasive DNA test or amniocentesis in time to find out chromosomal abnormality and terminate the pregnancy in time if necessary.