Ultrasound accuracy? i had an ultrasound that dated me at 13 weeks and 3 days..how accurate would this dating be..could it be two weeks off?

Early : Early ultrasounds are now amazingly accurate. There are very rarely off by even a few days. They are very reliable indicators of gestational age, and are much more accurate than going by the date of last menstrual period.

Yes: Ultrasound dating accuracy is best in the first trimester. After that, ultrasound dating is less accurate. Here is a link which may help you: http://www.Ultrasoundcare.Com.Au/services/pregnancy-ultrasound-5-17-weeks-dating-and-viability.Html.