Are dating scans accurate?

[julietaboolie]

Based on LMP midwife worked due date out as 6/7 Jan.

I have a short cycle though and I know the exact date I conceived, and worked my due date out as 3/4 Jan.

Now dating scan is saying 30 Dec which I don't think is physically possible!

Is it possible for it to be wrong? Which date should I trust? I'm confused....

Scans at about 12 weeks are usually accurate - before or after this there seems to be more chance for error, especially the later you go from 12 weeks. The problems come when mums dont have dating scans at 12 weeks and they try and date from the 20 week scan when babies are different sizes.

Implantation happens approximately 10 days after conception and I think it has a range of anywhere between about 7 and 14 days - hence why some people can get a really early bfp at 7 dpo, others have to wait a bit. This can be different with every pregnancy - I know I got a bfp at 8 dpo last time but wasnt until 14 dpo this time (although ov date was a bit dodgy this time).

So yes the scan could well be right - you may have ov'd early and then implanted quickly as well meaning that baby started growing quicker?

I know its annoying to have different dates but a difference of four or five days really doesnt mean a lot in medical terms. I realise in emotional terms it can be far more annoying though!

I know that my dates are right (date of conception as well as LMP) and my dating scan gives me a date that is 5 days out. I am insisting that they stick with the later date, as I am determined not to be induced just because my dating scan says that I'm "late".

I am certain of my dates as I conceived using IUI but the dating scan was five days out. it drives me nuts because they insist on using 'their' dates when I know absolutely that it is wrong.

I also agree with Mrs T that being out by a few days can have consequences. I am having a c-section, and the hospital is insistent that it must be 7 days before due date and that this has been chosen for medical reasons. If their version of 'due date' is five days out, the section timing will be wrong

i had an early dating scan, when i worked myself to be about 8 weeks, but was told was only about 6 weeks.

However, like you, its impossible, for me at that time not to have been AT LEAST 8 weeks, as husband on boys holiday at time (as was sitting final university exams) when would have been concieved IF i was 6 weeks!

So when THAT small, i'm sure they can get it wrong. Awaiting 12 weeks Scan, as turn 12 weeks by my dates to confirm whether right or wrong!

xx

With my Ds, I had the date of the 8th of the month, the scan said the 12th...he arrived on the 10th!
Dd was due 19th by my dates and scan and arrived 26th...

Well there's no way my dating scan was accurate. For a start my cycle is long and they didn't take that into consideration for initial date, the date of conception they calculated I had a dreadful cold and there's no way DH would have come anywhere near me. I was induced at 40+12 (by their dates) and DD weighed 6lb4oz, If she was born on their EDD, she'd have been tiny.
There's no way I'd be induced again, as I believe the cranked her out too early.

bear in mind though that DH doesn't have to be near you for conception to occur....

Sperm hang around for up to 7 days so could catch an egg just as its ripening or as it's nearly given up!

I know exactly when I ovulated but due to a dose of flu didn't have DH near me.... My date gives a due date of 26th Jan and I know it might be on that day or before or after that - my dating scan says after by 2 days. I had a doctor scanning me though and think they are more accurate sometimes....

I think my scan date is out by 2 weeks, as again like a few of you, I know when we made things happen.

They also arbitrarily picked a wednesday as the day to use as that is the day I had my scan on, but my LMP was a Sunday - only a bit different. But hey ho, baby will arrive when it wants

:-)