Early scan dates don't add up

[Bumblebeee]

Hi, I went for a private reassurance scan this afternoon to check everything is how it should be and just to try to calm my nerves a bit because I am just an absolute wreck at the moment. I don't get periods very often (PCOS) so I have no LMP date to go by so I just worked it out approximately going by the dates that we dtd, the days I had ov pains and how long after I got the positive pregnancy test so the most likely one made me 6+5. My scan today measured me at exactly 6 weeks with a little 4.1mm baby and a strong flickering heart beat which I'm obviously over the moon with but for me to be 6 weeks today, I would have conceived on the 11th which was 3 days after we last had sex which I know can be quite normal but that would mean I would have got my positive pregnancy tests not even 4 days after conception which I didn't even think could happen. Anyone else had anything like this happen to them? I know 5 days isn't huge but how would I have tested positive like 3.5 days after conception?! Confused!!
(The blue on the chart is when we dtd and the green plus sign is the day I had a positive test)

 

[Sander]

When I was scanned I measured at 6+3, I wasn’t 100% on my dates and I asked for another scan at 13 weeks to confirm - my midwife told me scans that early aren’t accurate (I believe best time is between 7 and 9 weeks?), anyhow - they took the 13 week date instead which was 5 days ahead of my original due date. She said that 6+3 scan was just too early. So it could be that baby’s measurements just look small now but if you get a 12 week scan done they may bump your dates back up.

(DS1 I had a scan at 7+3 which lined up perfectly with what I thought my conception date was)

 

[OnErth&InHvn]

They change the dates quite often. Even if you do know the lmp, they still change it.

 

[robo123]

I was 6+6 and measured 6+2 with a 5.9mm little bean. Xx

 

[J.D.]

Yeah, my scan at 7+5 (from IUI) was dated at 7+1.

The week before I had a scan at 6+3 and it measured 6+5.

Neither caused the technicians any concern at all.

 

[Scout]

The dates can be off. On my OB's ultrasound machine, there is a +-6 out beside where the date comes up when measuring the fetus. In other words, 6 days off either way can be normal. I had scans every week from 5 weeks thru week 14, always on Tuesday, and I think I measured exactly 7 days only once.

 

[HLx]

This has been me this pregnancy!

1st scan to rule out ectopic I was 6+6 and was supposed to be 7+2

12 week dating scan based on the earlier scan dates I was 12 weeks bang on, I ended up measuring 12+4

Had a follow up scan at 14+2 due to bleeding, I measured 13+6

Had a scan at 15+2 with my consultant and baby measured bang on.

Had a private scan at 16+4 and finally measures bang on again!

So I wouldn't worry about a few days here or there! Baby boy is very happy in there lol

 

[Bumblebeee]

That is good news, thank you all. I fell very lucky, we paid for a private scan in the City centre and the sonographer there is also a midwife in my local hospital so she said to go and book in with the doctors and tell them that this midwife has requested for my files to go to her desk and then she will book me in for an early scan up the hospital. I think she could tell I was a nervous wreck, my legs were shaking uncontrollably

 

[Monkei]

Went for a scan at 7 weeks and measured 6 weeks had my 12 week scan and the growth showed my original dates were correct x