Ultrasound scans are normally performed through the abdomen, but they can also be performed through the vagina.
For a trans-abdominal scan, you lie face up on an examination table with your abdomen exposed and a cool gel is rubbed over your tummy to improve the sound conduction.
The sonographer then slides the transducer (which looks a little like a telephone receiver) over your stomach in order to transmit sound waves. A computer translates the resulting echoes into images on a monitor, and your baby can be seen on the screen.
Your baby’s measurements will be recorded during the ultrasound scan, and the sonographer will take still pictures or video for interpretation by your doctor.
Whilst you may be keen to know what can be seen from the ultrasound, you may need to wait until your ultrasound technician has looked at the results before they are discussed with you.
If you don’t want to know the sex of your baby, make sure you tell the sonographer so that she doesn't’t let it slip!
A standard diagnostic ultrasound takes around fifteen to twenty minutes. A more detailed (level II) scan, which may require the use of more sophisticated equipment, can take anything from thirty to ninety minutes or more.
These days, ultrasounds in the first trimester are more likely to be performed through the vagina, using a specially designed probe.
This may be a rather uncomfortable method, but it generally provides better quality images in the early stages of pregnancy and can be particularly useful in diagnosing ectopic pregnancies and fetal abnormalities.
If you have a trans-abdominal ultrasound in your first trimester, you may be required to drink several glasses of water beforehand so that you have a full bladder during the procedure.
This can be rather uncomfortable but may help the sonographer get a clearer view of your baby during the ultrasound procedure.