One gestational sac...twins possible?

[sara87]

hi.i have a question, google has made my mind go haywire on this. i actually had my first ultrasound at 7 weeks 4 days. It showed one gestational sac, a heart flicker and fetal age corresponding to 6 weeks. is there any possibility of twins? oh i sooooo adore twins! would love to have a normal and healthy pair! but are my chances bleak??
by the way i do have a good family history of twins.

I don't understand, there was one sac, one heartbeat so why do you think it could be twins?

What sort of family history do you have? Identical or non-identical? My understanding is that non-identical twins can run in the mother's family line as there can be a genetic pre-disposition to releasing 2 eggs at a time, whereas identical twins are when a single egg splits - this is not a hereditary feature.

It sounds extremely unlikely to be twins if you have seen one sac and one heartbeat.

Sorry, but I don't understand why you'd think it was twins either if you have one sac and one hb.

Non-identical (fraternal) twins can run in families but in that case two eggs are fertilised so there would be two gestational sacs.