It is common for nasal bone ossification to be absent or not visible during a scan at 13 weeks of pregnancy. However, it can sometimes indicate a higher risk for certain chromosomal abnormalities such as Down syndrome. Your doctor's advice to repeat the scan after 2 weeks is a precautionary measure to ensure accurate assessment of fetal development.
During the second trimester, around week 18-20, nasal bone ossification becomes more visible on ultrasound scans. By waiting for another two weeks, your doctor will have a better chance of detecting any changes in the nasal bone development.
It's important to note that absence of nasal bone ossification alone does not confirm any abnormalities in your baby. Other factors such as blood tests and nuchal translucency measurement are also taken into consideration when assessing overall risk.
If you are feeling anxious or have additional concerns, it is always best to discuss them with your healthcare provider who can provide personalized guidance based on your specific situation.