I agree with adgal. Also I posted a more complete reply on your other thread. Best wishes for you.
Sorry, I'm a bit confused...they saw a heartbeat and said you miscarried? Or there was no heartbeat?
If there was a heartbeat I have never heard of a Dr. calling it a miscarriage.
If there was no heartbeat, it would be dependant on how far along you were. When was the first day of your last menstrual period? Typically a heartbeat can be seen on ultrasound between 6 and 7 weeks. If you are not comfortable with the diagnosis, there is no reason to make any big decisions such as a d&c right now. I would request a second ultrasound for 1 to 2 weeks from now. I'm sorry your having a stressful time and will keep you in my thoughts.