Accuracy of early dating scans and due dates

[Sarahjane282828]

Hi,

So unexpected but very happy mamma here needing some advice. How early are transvaginal scans at dating at weeks 4,5,6??

basically I am (was) in an open relationship on contraception but found myself pregnant. At 32 I feel happy with this but want some further clarity for peace of mind :)

very early.. only 6 weeks now according to scans. Basically I had sex with a man on 17th July, came on period on 26th July. He did not do the deed inside me.

Period ended on 31th July and only slept with partner since. Had a negative pregnancy test on 16th Aug but then faint positive by 21st. I’ve had one scan a week since finding out (found out at 3w 4d) due to my health complications, all have dated me less than 6 weeks now. Only last week only a sac and yolk was seen, no embryo or heartbeat yet. Nothing was seen in my two earlier scans.

basically I want to know the accuracy of early dating scans, and that there is no way it’s the first guys? If it was it would put me at 7/8 weeks on my last scan when not much was seen more than yolk and sac. Thanks :)

If you have only had sex with your partner since your period it’s unlikely to be the other guy and you would be less than 6 weeks

Early on you won't see an embryo. The earlier, the harder to date accurately. Accurate dating from about 12 weeks

I got a dating scan at 8 weeks which was accurate. They told me that was the earliest they could be sure.

You've had sex with 1 person since your last period - he's the father of the baby