Fetal radial defects are usually not visible at 13 weeks of gestation.
The primary ossification centers of the bones can usually be clearly distinguished by ultrasound in the early and late stages of pregnancy, and it is usually at 14 to 35 weeks of gestation that the fetal extremities are shown at a higher rate under ultrasound. Fetal radial defects are best detected at 18 to 28 weeks of gestation.
Because the fetal limbs are too short before 12 weeks of pregnancy, it is difficult to distinguish; after 28 weeks of pregnancy, due to the relatively less amniotic fluid, the fetus is larger, resulting in limb compression, fetal limbs are not easy to display; after 36 weeks of pregnancy, the fetal limb display rate is further reduced, so the 13 weeks of pregnancy generally can not see the fetal radial bone defect.
Therefore, pregnant women should follow the doctor’s instructions for regular obstetric examination, and continuous tracking ultrasound in early and mid-pregnancy can improve the rate of prenatal diagnosis of fetal radial defect.