Having an antenatal scan in the first few weeks of pregnancy can be thrilling. It’s wonderful to see the little blob with a heartbeat that will become your baby!
What is an ultrasound?
An ultrasound examination obtains a picture of the inside of the baby without using X-ray. It involves sending a special sort of sound
wave (inaudible to the human ear) through the skin. The sound waves are reflected by the womb and the baby, and these ‘echoes’
form a picture on the screen.
How is an ultrasound carried out?
You will be asked to loosen any tight clothing and lie on a couch so that the midwife or the doctor can apply gel (ultrasound conductor) to your abdomen.
This allows the transducer, which emits the sound waves to be placed on your tummy and move around easily to produce good
pictures. The gel is wiped off at the end of the examination; it does not stain the clothes and washes off with water. You are requested to have a full bladder for your early scan. For your later scans your
bladder need not be as full. The time to carry out an ultrasound varies, but usually it takes a minimum of five minutes but
more detailed scans can take up to 20 minutes.
What can an ultrasound tell about my pregnancy?
A great deal! The scans you are offered allow information to be obtained that is relevant to the stage of pregnancy you are at when the examination is carried out.
The first scan offered in early pregnancy can usually tell us:
- That you are indeed pregnant.
- That the pregnancy is situated in the womb.
- That the baby’s heart is beating.
- Whether you are expecting one or more.
- Whether the age of the baby agrees with
your own dates.
The 18 – 20 week ultrasound examination is where that baby is looked at in as much detail as possible, so that we can try to detect any possible problems with your baby. It should, however, be stressed that it is not possible to pick up all abnormalities by ultrasound and that this examination has some limitations. The quality of the pictures varies depending on a number of things.
Sometimes the position of the baby, the location of the afterbirth and the mother’s body size can make it difficult to get a really good view. In these circumstances, the scan may need to be repeated.
The doctor of midwife will tell you the results of your scan at the time.
How many scans should I get during my pregnancy?
The number of scans you will have depends on whether your pregnancy is considered low or high-risk. If you (or your baby) suffer
from diabetes or high pressure, or you had complications in a previous pregnancy, you might be offered more scans to monitor
your baby’s growth and wellbeing. You will be offered extra scans if you are expecting twins, too. Some hospitals do earlier scans for risk pregnancies and if you have private healthcare you might be covered for more than one. Private operators offer as many scans as you like, even on 3D.
Early pregnancy scans
Early pregnancy scans from six weeks to 10 weeks, are generally used when there is question about whether or not the mother has suffered a miscarriage; or if the pregnancy is ectopic (contained in the fallopian tube). There may have been vaginal bleeding or severe abdominal pain. Generally, these scans are done vaginally – they do not hurt and they give the best view of an early pregnancy.
Sometimes there is no heartbeat detected – but the woman may have her dates wrong and she will be asked to return in another week or two. A heartbeat can be detected from approximately six weeks.
First trimester scan
The dating scan is the first one and is done at around 14 weeks. The main reason for this scan is to date the pregnancy. It is also used to check for multiple pregnancies, see the baby’s heartbeat and check for some abnormalities.
The second scan is a structural scan and happens at around 20 weeks. This checks the size and development of the baby and the position of the placenta. You may be offered additional scans if your clinician feels they are necessary, if you have particular concerns or depending on the maternity care option you have chosen.
Seeing your baby on a screen can be a really exciting event. You can also take your partner, friend or family member along to share the experience with you. Your partner may accompany you to all your scan appointments but unfortunately children are not allowed. Recording devices are not allowed.
What is an anomaly scan?
An anomaly scan (taken at the 18-22 week stage) takes a close look at your baby and your uterus (womb). The person carrying out the scan (sonographer) will check that your baby is developing normally, and she’ll look at where the placenta is lying in your uterus.
This scan is able to check your dates, the number of babies you are expecting and it will show you the baby’s heart beating. The main purpose of the scan is to check that your baby is developing normally, rather than whether you’re expecting a boy or girl.
However, you may want to know your baby’s gender, or ask for a
photo of your scan. Bear in mind that the scan’s main purpose is to check that your baby is developing normally, rather than whether
you’re expecting a boy or girl. Sometimes excess wind or having too much tummy fat obscures the view, so it’s hard to tell a baby’s gender accurately. And some hospitals have a policy of not telling parents-to-be, to prevent mistakes from happening. Ask your midwife about your hospital’s policy.
Deborah Sudding, Clinical Specialist from The Ultrasound Suite gives some expert advice on 3D and 4D scans.
What benefits do 3D and 4D scans offer over the normal scans that a pregnant lady is offered in a maternity hospital?
The 3D /4D baby scans gives you a unique opportunity see what your unborn baby is up to during pregnancy. Time is taken to capture 3D images and 4D video clips – the fourth dimension is the moving part.
From 25 weeks onwards, the face of your baby becomes very clear and features can be identified in 3 dimension. This is a great bonding experience – especially for the dads.
Some of the things we have witnessed on 3d4d scans include babies yawning, drinking, smiling, sucking their thumbs, putting their feet or umbilical cords into their mouths, opening their eyes and even pulling grumpy faces!
Are 3D and 4D scans useful for spotting potential problems with a baby’s development in the womb?
3D/4D imaging shows the surface of the baby and not the internal organs. They can be useful for assessing some anomalies such as facial defects like cleft lip, open spina bifida, clubbed feet etc. but they are not typically diagnostic scans. 2D (black and white) scans see straight through the baby, allowing the sonographer to examine the internal organs.
Most anomalies affect the internal organs so the 2D scan will remain the gold standard in fetal imaging.
The Ultrasound Suite in Bray and Grafton Street is one of the few centres that provide a 2D well-being baby scan in conjunction with your 3D/4D baby scan all for one reasonable price as they believe that the health of the baby is of utmost importance.
What stage of pregnancy is the best time for a woman to have a 3D or 4D scan? And what are the reasons for this?
These scans can be performed from 12 weeks onwards. The images become clearer and more realistic as the pregnancy goes on. It is important to have enough fluid around the baby and for the baby to be big enough to produce realistic images. 30 weeks gestation is the optimal time to get the scan done.
Some patients are too excited to wait that long so they have a Mini 3D/4D scan at about 18 weeks (when the gender can be seen too) and another Mini 3D/4D scan at 30 weeks.
Read our other articles on Health in Pregnancy
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