Scan dates seem literally impossible?

[Qally]

I just had a scan, and they said I was 8 weeks 2 days. Thing is, if that's the case it's an immaculate conception, because DH was away for three weeks from a date that would make me almost 10 already at the very, very earliest - and even allowing for utterly lazy sperm, still well over 9. I've known I was pregnant for over 5 weeks, and it was a cheapie after-the-period-is-due test and we weren't even trying! Yet the sonographer was adamant that this early, there's great accuracy. Um. Should I anticipate a celestial visitation any day? Because I can't help thinking that the scan being wrong is more probable than this being the Second Coming. (Or, you know, Damien.)

The reason I'm so bothered about this is that our trust won't perform nuchal scans, so I need to go privately, and I was planning to rely on this dating scan to know when to book - our trust have also asked that I use that scan in lieu of my NHS 12 week one, so want me to book in at 12 weeks by their calculations - but I don't trust their calculations, as I know they're impossible, and I know nf tests aren't doable after 13 weeks. Fail to see why I should blow the best part of 200 quid on a test that may well result in my being told "too late, sorry." Should I just calculate back to the last possible time I know I could have conceived, or take the scan date, or what? I'm really confused.

I'm assuming your cycles are not reliable, or you would have a period to work from?

Have you accounted for pregnancy weeks starting on the first day of your lats period, ie: probably about 2 weeks before you've even conceived? So when you conceive, you are actually considered to be 2 weeks pregnant.

Period dates agree with my dating - last mp was 26th Jan, which makes me just over 9 weeks.

AHLH - yes, I have.

did you query the dating at the time?

Yes. I was told that this early, scans are infallible.

the scan might well not be accurate.
I had countless scans in late pg to monitor suspected IUGR, when DD hadn't grown at all between a scan at 20 weeks, and one at 28. Susbsequent scans indicated she was growing again, at a reasonable rate. after a while the consultant decided that the best explanation was that the measurements from the 20wk scan were really rope . so I would guess that the same may well have happened to others.

do you have a walk-in clinic at your early pregnancy unit? could you find a reason to go there?

this happened with ds i was sure of my dates, and they placed me 2w later. all of my milestones occurred 2w earlier than they should (kicking etc) did they mention anthing else?

• ropey, even

More important than the first day of LMP is your cycle length - ovulation occurs 14 days before the first day of the next period. IME nothing is infallible BTW.

FWIW I conceived dc3 at a time in the month when it should have been impossible, and I was using contraception. Thank goodness she looks like DH, and her siblings....

I don't think they can say the scan is totally reliable to the day.I think they still have a +/- 7 days leeway so you could be 9+2 days even by their scan.
Also I think you can do nuchal scan at 11 to 13 weeks so if you booked it at 11 weeks from their dates you should still fall in the time it's ok to have it done even if you are 2 weeks further on....if you are paying for it you should be able to book when you like.

Perkinwarbeck, this WAS the EPU!

I think I'm just going to go on my own dates, after all I can still get an accurate nf scan at 11 weeks, but can't at 13, and I don't see why NHS convenience should be my leading criterion if I'm paying. And if they can't tell the difference between 8 and 9, not sure how they can 11 or 12 either. Besides, if their dates are right, I did a positive pregnancy test one week after conception, when my husband had already been gone two weeks. That's clearly nonsense.

Lissielou the pregnancy looks totally healthy - yolk sac visible, very clear heartbeat, well positioned, sonographer said she also saw some fetal movement though how I don't know, given how tiny the mite still is.

I was losing patience with the NHS as was having no luck or answers in getting a scan date. I wanted reassurance and to have a scan before telling work so I booked a private one. Literally as I came home from the private one I had the letter with a scan date 2 days later.

Anyway there were 5 days difference between the private and nhs scan (private was bang on my dates as I knew when I ov'd).

This was also at around 12 weeks when its supposed to be "exact".

If you are really that concerned could you pay for a private scan to check? However I think there is quite a wide window for nuchal scanning - 11 to 13 weeks or something (according to the place I spoke to) so perhaps book it so that both your dates fall within the window?

xx

Hi there. I am no expert but can only tell you of my experience! Ds 2 was given an edd date of 5th nov which didn't work with my dates at all. I questioned but they insisted, like your songrapher did, that the earlier the scan, the more accurate the date. ( I had my first scan at 6 weeks, then 8 weeks,(due to presvious miscarriage) then 12 weeks then 20. I then had growth scans at 28, 32 and 36 weeks) Each of my growth scans showed my lo at least 3-4 weeks further on than they said. I was convinced my lo would arrive in Oct -hence I joined the oct post-natal thread!- not Nov.

BUT, I went into labour on the 4th and he was born on the 5th -his edd. He was a large boy but that isn't a factor with the very early scans.

(I started this post an hour ago but he was hungry again so had to feed him! Sorry if I'm way behind now x)

I had to pay for my NT scan - when I first turned up at what I thought was 12 weeks, they said they thought I was actually 10 weeks which was too early, but they let me come back without charging me again. So would it be worth booking your scan for a date that is either right or too early, depending on which date you take (if you see what I mean), and then going back if you need to?

hi i had a similar experience, 8 week scan out by almost a week. (as confirmed at my 12 week NT scan) My midwife said that the most accurate time to have a scan is at 12 weeks, no matter what your sonographer said to you, i would work on it being wrong.
you can have a NT scan between 11 plus 5 and 13 plus 5 so don't worry.
hth

Aren't scans based on a 28 day cycle, with Ovulation on day 14?
Right well, that means it doesn't apply to 99.999999 % of the female population then.
Joke. But seriously, I don't know what % of women do 28 days, 14 ovulat, but I bet it isn't THAT big.
So there rides your leeway in scan dates before we even begin.

I had an early scan at the EPU at my local hospital. They concluded that I was 8.5 weeks (but they did say give or take).

At my later '12' week scan they insisted that the original date was at least a week out at that I was a week further along than thought.

My due date has been put back by a week as well after two early pregancy scans and my 12 week.

I know that it wasn't possible by LMP dates because a) I always have a regular cycle and b) apparently I conceived around Christmas when my parents and both DBs were staying and we did not have room to ourselves. I think I would have remembered!

But we'll see when the little tike is born. I htink the whole area of conception is a bit of a mystery really...