Am 6weeks pregnant....fetal heart beat ***** be evaluated...?

hi ..iam six weeks pregnant....got my scan done 2day...it says intra uterine pregnancy...it shows a healthy yolk sac...but fetal heart beat could not be evaluated... my doc wants to rule out the posibility of blighted ovum , so she has asked me to repeat the scan after 10 days....iam so scared...is everything alrite.