How long after pregnancy can you do B-ultrasound?

Generally, B ultrasound can be done at about six to seven weeks of pregnancy. This time, B ultrasound is mainly to determine whether it is a normal pregnancy. Under normal circumstances, the gestational sac can be seen through B ultrasound at about five weeks of pregnancy, and the obvious embryo can be seen at six to seven weeks of pregnancy; the human shape can be seen at about eight weeks of pregnancy.