It is recommended to do ultrasound around 40 days of pregnancy, most pregnant women around 40 days, the pregnancy sac has entered the uterine cavity, can be more clearly determine the location of the pregnancy sac and the size of the sac. Some women who are particularly accurate in menstruation can already see it on the 35-36th day of menopause. The purpose of ultrasound is mainly to rule out ectopic pregnancy. If you have abnormal abdominal pain and bleeding shortly after menopause, you need to have an ultrasound earlier. In early pregnancy ultrasound, most of them are vaginal ultrasound, because vaginal ultrasound is more sensitive than abdominal ultrasound, see more clearly, and do vaginal ultrasound will not affect the baby.