How worried should I be? Less developed at early scan than expected

[IWantDogger]

I had an early dating scan today - heartbeat was visible and measured 6w 1 day. All fine, BUT I took a test 3 weeks and 1 day ago so I was assuming I was minimum 7 weeks along.
Going by the scan, I would have tested positive 1 week after conception - 3 wks pregnant. Is this even possible?
When I tested it was midday, I got a faint line I a high sensitivity internet cheapie then a +ve on clear blue digital which said 2-3 wks (from conception). A week later I still got 2-3 wks.

It doesn't sound good does it?
Should I brace myself for a miscarriage?

I'm going back to be scanned again next week. This is (unplanned) dc3. I had a mc between 1 & 2 where a hb was seen on an early scan but I was a couple less weeks than I though, week later I mc.

It could be a number of things; the scan could be out as at this point it's so tin it's hard to be 100% sure of accurate measurements.
The clear blue shouldn't be relied on for dating the pregnancy so that could have been out.
There's loads that it could be. I'm afraid it's a wait and see. Horrible but you will know more next scan.
Sorry. Hope times go quickly for you

I would try not to worry. I think scans can be out. FWIW, although a bit later on, I had a scan at 11 weeks (due to spotting) with this pregnancy where they dated it at 10+4 (also unplanned DC3, so I wasn't 100% on dates and accepted the scan date). Then I had another scan, my official "dating" scan exactly a week later, where I would have been bang on 12 weeks by my dates, and 11+4 based on the scan. This scan put me at 12+4, i.e. 2 weeks worth of growth in one week going by the scans. I've concluded that scans really aren't an exact science, and when the measurements being taken are so tiny there's got to be quite a lot of room for error.

I was worried after a scan at 7 weeks put me a week behind, but then at my 12 weeks scan a couple of weeks ago I was right on track for where I thought I should be. Like the others say, scans aren't always completely accurate, so try not to worry - though I know that's easier said than done! x

Thankyou for the replies. I'm pants checking even more than before though she said my cervix was long & closed so I guess that's a good sign for now. I guess it's not over til it's over but I think its not looking good. The only hope is she's made a mistake or it's just a foetus on the small side as I think there's pretty much no way I could have tested positive one week after conception when it wasn't even the first wee of the day.

Having a heartbeat is a real positive, congratulations. Although with you history, I can see why your concerned. I think the risk of miscarriage at 7 weeks, after detection of a hb is under 5%. Thats 95% of Mums who take a baby home.

My baby which was measuring behind my dates at 6 weeks arrived on the due date I calculated, and is now 3.

I was the same knew my dates as I have a long cycle and we only dtd once that month and ovulated early I was scanned at what I thought was 7 weeks I was 5 weeks then told to wait ten days my epau nurse was matter of fact told me not to build hopes up worse 10 days of my life, went back up cryed in the car thinking this was it and I was 8 weeks 1 day so 3 weeks growth in 10 days she is still tiny but I'm now 32 weeks so anything is possible, we had been trying 18 months and this was our last month b4 ivf started as I'm peri menopausal at 29 so I'm glad and its a miricle she's stuck everything thrown at her, she's feisty I'm dreading the teenage version of her already!

The sonographer told me that there is a margin of error of plus or minus 5 days with scans. Combine that with the fact that dates may be out by a few days, and I wouldn't worry too much. Easier said than done I know (I have been in this position twice!) but there's no point getting too stressed out when it's just uncertain at the moment. I really really hope things work out for you xx

I had a scan at about what I thought was 4w6d and they said 5w3d. Then another exactly a fortnight later, I was expecting them to say 7w3d but they said between 6 and 7 weeks... I was really really worried, but they said everything was as it should be, and the scanners weren't really that accurate that that stage because the fetus is so tiny. Then at my 12 week scan, they moved my dates forward by two days, and said the baby was slightly above average in length. So really, try not to worry! I had to have a private scan two days later, and the baby had grown by 5mm in just two days, they said that was normal too!

Ok thankyou. I will try to stay neutral in my thinking and remember all is not lost at this point. 4 weeks ago I would have happily and genuinely told anyone that asked that we weren't planning any more and were happy with our two, amazing though how you can get very attached to the idea of being pregnant and having another baby in such a short space of time.

I don't think that sounds unlikely at all- new tests are so sensitive, if anything, it's great you tested positive so early! Plus- the two week ovulation thing is only true if you did ovulate then- what is to say you did? Don't over think it.

A lines a line and a heartbeat is a HEARTBEAT! Please take solace in that and I hope your next week goes quickly.

Just to update, unfortunately at the second scan today there was no heartbeat and there had only been a couple of days worth of growth since last week.
Very sad but at least I was prepared.
Now just waiting for the inevitable. Going to epu on Thursday.

Really sorry to hear that.

Oh bless you, was reading through and I wasn't expecting you to have such a sad update. I hope u get through the nxt few wks with ease. Jo x

I had early scan at what I thought were 6+6 and 7+6 but got told 6+0 and then 7+1 and by time had 12wk scan was back on track with my dates and was 12+5 but by early scans would have been around 12 or just behind.

Sorry should have read to end before posting sorry to hear your news

So sorry to read this, something similar happened to us earlier this year. I was 100% certain my dates were right but an early scan put me back just over a week meaning I wouldn't have even been 3 weeks pregnant when I got my BFP. I think I knew then things weren't gonna work out and sadly they didn't. Sending big hugs xx

Scans can be out. I had one just a week ago. I was told 6+2. I was a bit because whilst possible i am sure i lucked out on an early bfp anyway so i was sure if i was only 6 weeks something was wrong.
So i had another scan (prev mc hcg scores of oddness). Yesterday i was 8+2. Baby "grew" 2 weeks in one.
Tiny mm make a big difference at this point. It's nerve wracking and inconclusive.

As for clearblue indicator pffft to them they can only use 'average' figures ... Noone is exactly average. Plus it's the overspill hormone level fromyour blood filtetrd by your liver and kidneys into your urine. It can vary a LOT.

Thankyou, I think its useful for other people who might be experiencing similar and reading the thread in future to see that things can go either way.
But also, it's always a good idea especially with these sorts of threads to note the date of the OP and check through to see if there's been an update before just posting. As you'll see, I did come back to update and it didn't end well for me.