This is the traditional ultrasound technology like what you receive at your doctors office. Sound waves are used to produce images of slices through the body. A transducer or probe which emits ultrasound waves is placed on the skin after coating it with a thin layer of conductive gel to make sure the waves pass smoothly through the skin.
3D scanning uses advanced ultrasound technology to produce imaging in three planes. These can then be reconstructed so that the images appear to be as you would see the structure in real life.
4D ultrasound allows us to see realtime activity of your baby