Large rejection and four-dimensional ultrasound are two concepts of B-ultrasound during pregnancy, and their emphasis is different. Under normal circumstances, a pregnancy test can be either one or the other.

Four-dimensional is developed on the basis of two-dimensional and three-dimensional color Doppler ultrasound, which can dynamically and stereoscopically observe the fetal structure.

B-ultrasound with abnormal ovulation is in the second trimester of pregnancy, that is, around 24 weeks, and fetal malformation is carefully screened by B-ultrasound. Abnormal ovulation can be two-dimensional, three-dimensional or four-dimensional, so abnormal ovulation and four-dimensional overlap in concept, but they cannot replace each other.

From the point of view of clinical work, if there is a large area of abnormality in Hebei Meihe Maternity Hospital, it is best to do a large area of B-ultrasound, because four-dimensional B-ultrasound sometimes cannot completely replace a large area of abnormal B-ultrasound. In some hospitals, large-scale anomalies are made through four dimensions, so we directly choose to do four dimensions to make large-scale anomalies. However, in some hospitals, the large-area malformation is completed by two-dimensional B-ultrasound, so we can directly choose B-ultrasound for large-area malformation.