It really depends. If they are having trouble seeing the baby or hearing the baby then the blood work is to double check, but most likely if they are very worried they will send you for ultrasound right away. If they tried on a doppler sometimes its hard to hear the baby until your in your 14-16th week.
Did they only try to do a doppler or did they do an internal u/s?
Did they only try to do a doppler or did they do an internal u/s?
did you have any other u/s so far? did he see a sac? i just need a little more info