A Doppler scan measures the blood flow through the umbilical cord and around different parts of your baby's body, such as his brain and heart. This helps to show whether he's getting all the oxygen and nutrients he needs via the placenta. You can have a Doppler scan at the same time as a normal scan, as it uses the same equipment. Most ultrasounds have a Doppler function. The person carrying out the scan (sonographer) will put some gel on your tummy and move a hand-held device (transducer) over your skin. The transducer sends out sound waves that bounce off the blood flow to your baby's body via the cord, as well as his blood circulation system. This creates an image on a screen showing the sonographer how the blood is flowing. It gives a good idea of how your baby's doing.