can a ultrasound be wrong?

[nylamc]

i had a ultrasound on jun 28 2011 and it said i was 13weeks 0days, so i counted back 13 weeks and it said i conceived about march 28 or 29, but i had a period apr 7 and it lasted about 5 days(normal) for me. i took 2 hpt at the end of apr around the 25 for the first 1 and 28 the second 1 and both were neg. i got a pos test on may 3 so im very confused at this point and i still question my due date which is jan 3 2012 and according to my lmp i should be due about jan 11 or 12 that almost 10 days and my ob keep saying is ok????? but im not ok with the dates

[ChristineMP]

You ovulate about 14 days before the start of your period. So if you ever have a short cycle (say 24 days from the first day of one period to the first day of the next and you ovulate 14 days before the start of that second period...if your period lasts 5 days you ovulated 5 days after your period ended. If you have a very short cycle it is possible to ovulate within a few days of the end of your period.

I hope this helps.

[nylamc]

that seems to make a little more sense to me... and thats a good reason because the ultrasound tech did indeed seem to really not know what she was doing and when i got my 2nd ultrasound aug 8 i had the same tech and it was the same issue some else had to be called in to assist her and help her as well.far as the ovulating early i kinda thought so myself so when i ask my doc she explained the its kinda unlikely do the fact my lining of the uterus having even prepared to bulid back up frm the bleeding (idk) something in that form.. i never heard that you ovulate a day or two after your period stops??

[AnnieBrooke]

Don't count back 13 weeks from a pregnancy date given you by an ultrasound if you are trying to figure out when you conceived.  Medical dating counts back to your presumed first day of your last cycle, not to your conception date.