How can a color Doppler ultrasound detect pregnancy

Patient's question:

No

Doctor's answer:

Ultrasound can determine the gestational age based on the size of the gestational sac. Typically, the maximum diameter of the gestational sac (cm) + 3 is an approximate gestational week, but this is not very accurate. If an embryo is observed, the embryo length (cm) + 6.5 is an approximate gestational week, which is more accurate than determining the gestational age based on the gestational sac.