i agreed with jake & gina... when i thought i was 6wk (based on my LMP), but from the scan, baby sac only measures 10mm, equivalent to 4w0d... 1 week later, it measures 1.7cm, equivalent to 5w1d... i've done so many early scan cause i have continous bleeding and spotting.... all at GP clinics... but when i went to OBGY (specialist) (3 weeks later), dr did scan, and measures the baby crl 22.8mm, 9w0d... so, dr stick to my EDD based on LMP since it's only 5 days different... weird isn't it... so, it all depends on who did the measurement....