Ultrasound in Pregnancy

During an ultrasound scan, high frequency sound waves are produced by a transducer (the part of the machine which is placed on the body). The sound waves are passed into the body where they encounter structures (like your baby!). When this happens, the waves reflect back, and the sound (or echo) is detected electronically and transmitted onto a screen as a dot. This results in a picture being formed, with strong echoes creating white dots (representative of bone), weaker echoes creating grey dots (tissue) and no reflection creating black dots (fluid).