Fetal nasal bone length standard comparison table

What is the standard value of the fetus's nose bridge? Most pregnant mothers may not know or care about the problem of the fetus's nose bridge. They will only pay attention to it when there are abnormalities in the information shown on the prenatal examination report. The editor below has sorted out the standard values ​​of the fetal nose bridge and some related issues. Let’s take a look.

Standard value of nose bridge of first-born baby

The nose bridge of the fetus is usually accurately measured between 11 and 13 weeks of pregnancy, and the standard values ​​for the length of the nose bridge are as follows:

The average value from 11 to 11 weeks was 2.3 mm (1.5 to 3.2 mm); the average value from 12 to 12 weeks was 2.6 mm (1.4 to 4.2 mm); the average value from 13 to 14 weeks was 2.9 mm (2.1 to 3.8 mm).

However, the color Doppler ultrasound examination in the second half of pregnancy will also involve the precise measurement of the fetal nasal bridge. The standard value of the nasal bridge is different for different weeks of pregnancy, and there is usually a standard value range on the test form. For example, the standard value for 23 weeks of pregnancy is 4.55mm, and for 29 weeks of pregnancy is 5.35mm, etc.

Normal ultrasound manifestations of the nasal bridge of the second fetus

A standard normal nose sonogram has three clear lines: the upper line represents the skin, the lower line, which is thicker and has a stronger echo than the upper skin, represents the bridge of the nose, and the third line, which is almost in contact with the skin but slightly higher, represents the tip of the nose.

When checking the nasal bone, the ultrasound image will be enlarged to show only the head and upper chest, and the mid-sagittal plane of the fetus will be taken: the nose will be shown in the front and the rhomboid will be shown in the back. The nasal bone of the fetus is horizontal, and the camera beam is vertical to the nasal bone and at an angle of about 45° to the center line of the fetal face, and then the value is assigned.

Tips: NA: nose tip; NB: bridge of nose; UL: upper lip; LL: lip

The diagnosis basis for abnormal nose bridge of 3 babies

1. Lack of bilateral nasal bridge bones

During the joint examination of the mid-sagittal cross-section and the cross-section, if the mid-sagittal scan of the fetal face cannot show the strong echo of the nasal bone below the skin of the nasal bone (that is, both the orthogonal and planar images cannot show the strong echo of the nasal bone), and the cross-section of the nasal bone cannot show the strong echo of the two nasal bones located in front of the nose tip on the inner side of the frontal process of the superior maxillary bone, it can be diagnosed as bilateral nasal bone deficiency.

2. One side of the nose bridge is missing

When scanning the fetus's face in cross section, only one side of the nasal bridge can show strong echo, while the other side cannot show strong echo. However, in the mid-sagittal cross section of the face, a strong echo structure of the nasal bridge can still be shown, which is diagnosed as unilateral nasal bone deficiency. Color Doppler ultrasonography can show nasal bone deficiency in both sagittal and transverse planes as much as possible.

3. The baby's nose bridge is short and strong.

The length of the bridge of the nose is lower than the 5th percentile of the fetus of the same age, which is 0.25~0.35cm, which is diagnosed as a short and sturdy bridge of the nose.