Question about dates and nub theory

[3SSS]

If I got my nub pic at 11w3d (weeks based on an earlier dating ultrasound as well as the day I know I conceived), but I was measuring 12w2d, would my scan have the decreased accuracy that an 11 week scan has, or would it be more reliable than that because of measuring ahead?
Thanks!

[katewantsagirl]

The nub goes by gestational age so youd have a 12.2week nub not an 11day one

[pinkdreamer]

The nub goes by scan age, not LMP dates and so it would be more accurate than a 11 week scan. The best time for nub guessing is around 13-14 weeks though, if you get a good shot at this time it can be about 97% accurate :) x