Datinh scan wrong ??

[Ducky4kyle]

So according to my dating scan I.am.due 27may... This would mean I got a.positive just ten days after.conceving... plus I was not with anyone around this time. Is it possible the scan.was wrong... Would I go with my period dates or scan date

[AnnieBrooke]

Ah, excuse me, you said a 6-week ultrasound, didn't you?  Same comment but just change the 9 to a 6 above.  

[AnnieBrooke]

Well, it has to be three days off, or thereabouts.  Sperm can live up to five or six days in your system, some research suggests longer.  If you ovulated just a couple of days before the average, you could have conceived from the sperm that was still hanging around waiting for something to happen.  That would be consistent with results from a 9-week ultrasound.

[Ducky4kyle]

I had the scan at six weeks. But it has to be at least 9 days off becoz I didnt sleep with anyone 9 days before that date

[AnnieBrooke]

Hi, jess.  It's true that later ultrasounds will often give different due dates than earlier ultrasounds.  That's because embryos grow at different rates, and the further along the pregnancy is, the more variation there is between embryos and the more divergence from the average.  But for purposes of dating a pregnancy, an ultrasound in the 6th or 7th week is very close to spot-on, because almost every embryo reaches certain developments (in those early days) at the same time.  (For example, one day the heart is not beating, the next day it is.)  An ultrasound in the early stages is not something that can be relied on to be absolutely right to the very day, but at 6 weeks or 7 weeks it is not further off than a couple of days at most.  Later on, as you said, you will find the doctor needing to adjust the due date if the baby is growing a trifle slower or faster than average.

I asked the original poster when she had the ultrasound, because I was trying to assess how early it was in the pregnancy and therefore whether it would be very helpful for identifying the due date.  From the due date (if it is reliable) one can count back a certain number of days to try to get an idea of conception.

[jess674]

Dating scan? As in your first ultrasound? Ignore it, go by your period dates, my doc told me that they use mathematical formulas to calculate the due date at the first ultrasound (ie. measurements of the fetus, certain signs of development, etc.) They are based on statistical averages and may not be accurate. Every time I went in for an ultrasound I went home with a new due date it seemed. Every baby is different and develops at its own rate. I for one had both my babies early (according to  ultrasounds and my last period) and was given a list of potential medical problems they potentially could have and stayed in the NICU while they underwent a battery of tests to ensure they were fully developed and healthy, and they were fine (one was born at 34.5 wks and the other at 33 wks). Doc said they just developed faster than the accepted norm.

[AnnieBrooke]

This is what you got, or something close to it?

First day of last Menstrual period:  August 20, 2012
Probable date of ovulation:  September 3, 2012
Possible dates of conception:  August 30 to September 7, 2012
Due Date:  May 27, 2013 (40 weeks)

And you were not with anyone from August 30 through September 7?  and this doesn't align with your period?  How far along was the ultrasound, was it just recently?