Ultrasound scans use sound
waves to build up a picture of the inside of the body. The ultrasound
scanner has a microphone which gives off sound waves which are then
reflected back and converted into an image by the ultrasound machine.
What does a 2D
Ultrasound Scan look like?
With a 2D ultrasound, the
Sonographer can view different layers of the baby, from the outer
extremities to the internal organs. This differs from a 3D or 4D
ultrasound scan where only the outside of the baby can be seen.
When is the
In the UK, it is common for
two ultrasound scans to be performed during pregnancy; the first is
usually performed when the woman first attends the antenatal clinic and
the second at around 18 to 22 weeks.
perform the Ultrasound Scan?
Scans are usually performed
by radiographers or midwives who are specially trained in ultrasound,
and are known as Sonographers. Most have completed a post graduate
Certificate, Diploma or Master's degree in Medical Ultrasound.
How is the
Early scans (within the
first 10 weeks of pregnancy) are performed by inserting a small probe
into the vagina.
Later scans are performed on
the surface of the abdomen. Ultrasound gel is spread on the surface of
the skin and the scanner (microphone) is passed over the surface.
Normally, the pregnant woman can view the image on a monitor and will be
given a photo of the foetus.
Ultrasound Scans detect?
Scans within the first stage
of pregnancy (before 14 weeks) are used to check how many foetuses are
present and whether they are alive. The foetus(es) can also be measured
to accurately determine the birth due date.
18 weeks onwards, most organ
systems can be examined to ensure the foetus is developing normally.
From 30 weeks onwards, ultrasound scans can estimate how well the foetus
is growing. The umbilical cord can also be examined to ensure it is
functioning correctly. The location of the placenta can also be
checked. If your placenta is
(across or near to the neck of the womb), you will be offered another
scan later on in pregnancy to see if it has moved - the most likely
outcome - in which case it won't present any further problems. If the
placenta continues to block the womb, you'll be booked in for a
caesarean section around your due date.
If your scan suggests there is a problem with your baby, it's important
to ask how serious the problem is likely to be, whether there are better
scanning techniques at your hospital, (for instance MRI), that could be
used to give a more accurate diagnosis.
Ultrasound Scan detect the sex of my baby?
It can do from about 18
weeks, but if your baby is lying in an awkward position it may be
difficult to tell. Some hospitals have a policy of not telling women the
sex of the baby, as it is not usually possible to be 100 per cent
are Ultrasound Scans?
The accuracy of ultrasound
scans depends upon a number of factors including:
skill of the sonographer operating the machine
position of the foetus
quality of the scanning machine
are very overweight, the quality of the scanned images may be
Although scans are a useful
tool, they are not 100% definitive and may miss small problems while
identifying anomalies that rectify themselves by the time your baby is
Are Scans dangerous to me or my baby?
Ultrasound has been used in
pregnancy for nearly 30 years and there is no evidence to suggest that
scans cause harm to either mother or baby.
Some people think that more
long-term research needs to be done in order to make sure ultrasound is
safe, but others feel it is so widely used that any problems would have
shown up by now.