A 2D ultrasound is a (2-dimensional) cross-sectional scans through anatomy.
Now 2D imaging has been extended into 3D (3-dimensional) scanning and imaging.
The 2D mode is the traditional ultrasound mode, usually seen in the doctors office, with a black and white image.
The 2D mode is mainly images of the baby’s bones and the fluid.
The 2D mode is usually used to see the baby’s gender, and when the baby is younger in age.