B-ultrasound can observe whether the pregnancy site is normal (excluding ectopic pregnancy), and after pregnancy 13 weeks, B-ultrasound can clearly show the internal organs and bones of the fetus. By measuring the data, we can estimate the development of the fetus. It can also determine fetal position and placenta position, evaluate placenta function and choose delivery mode.

For ectopic pregnancy, B-mode ultrasound has auxiliary diagnostic significance. For pregnant women with abnormal uterus enlargement, it can be determined whether there is polyhydramnios or multiple pregnancies and whether the fetus is abnormal. If it is suspected that the fetus is a hereditary disease with chromosomal abnormalities, a small amount of villi, intrauterine cord blood or amniotic fluid can be extracted under B-ultrasound for further genetic examination.