Is it normal not see anything other than yolk sac in 6 weeks of pregnancy?

Inaccurate USS: Since many women do not have perfectly regular menstrual periods, dating of a baby in the womb can sometimes be off by a few days, or even a few weeks. At six weeks you can see the fetal pole heartbeat,chorionic and yolk sacs. But since ultrasound at six weeks may be inaccurate due to the above,as the pregnancy may actually be less than6wks, a repeat ultrasound would be done at a later date 1-2wks