Accurate ultrasound on age?

I got an ultrasound done when I was 18 weeks. The doctor said I measured 13 weeks just by measuring my uterus and such.. Well, then I went to my ultrasound (that same day) and the ultrasound technician said I am actually 18 weeks like I thought and not 13 weeks like the doctor had thought. How accurate can they be with measuring your amniotic fluid and your fetus because I heard its the most accurate when your in the first trimester. Opinions please? thanks!  

The ultrasound is the most accuret way to tell..

Quoting Brittany(♥):“ I got an ultrasound done when I was 18 weeks. The doctor said I measured 13 weeks just by measuring my ... [snip!] ... fluid and your fetus because I heard its the most accurate when your in the first trimester. Opinions please? thanks!  ”

Hmmm im no expert but i believe the u/s is more accurate b/c my sister is pregnanat and was measured small but at her anatomy scan my nephew measured just what he was supposed to...they say 1st trimester measurements are more accurate though...but like I said i'm no expert...any who, now her measurements are catching up but the doc said my nephew appears healthy...we'll see in abt 7 more weeks  

Quoting Jenesis Nicole's Mommy:“ Hmmm im no expert but i believe the u/s is more accurate b/c my sister is pregnanat and was measured ... [snip!] ... who, now her measurements are catching up but the doc said my nephew appears healthy...we'll see in abt 7 more weeks  ”

I know the measuring by the doctor isn't very accurate cause the baby could be sitting more towards your back or just the way hes laying can make you be off but im just worried the ultrasound wouldnt be so accurate cause I was in the second trimester.

Quoting Brittany(♥):“ I know the measuring by the doctor isn't very accurate cause the baby could be sitting more towards your ... [snip!] ... hes laying can make you be off but im just worried the ultrasound wouldnt be so accurate cause I was in the second trimester.”

my doc told me the u/s measures sthe size of the organs and brain and that helps determine gestational age...

Quoting Jenesis Nicole's Mommy:“ my doc told me the u/s measures sthe size of the organs and brain and that helps determine gestational age...”

Okay gooood! this helps a lot to know   thanks

Quoting Brittany(♥):“ Okay gooood! this helps a lot to know   thanks”

Ur welcome