Antenatal scans

Seeing your baby for the first time on a scan is amazing, but what do those shapes and shadows mean?

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Nothing beats the excitement of seeing the first grainy picture of your unborn baby on a scan, and during your pregnancy you’ll probably be offered at least two opportunities to watch her waving, kicking or snoozing. Guidelines for antenatal care recommend all pregnant women have a dating scan between 10-13 weeks, which works out how far along you are and estimates your due date. This is followed by an anomaly scan, between 18-20 weeks, which checks your baby is developing normally. While most women have both scans, you don’t have to have any if you don’t want to. Talk to your midwife if you are not sure. ‘Scans give you the opportunity to bond with your unborn baby, but don’t forget the primary function is to check that everything’s okay and possibly identify any developmental problems that could affect the way your baby is cared for,’ says GP and Prima Baby expert Dr Rob Hicks.

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What happens

Your scan should last around 20 minutes. You’ll see a sonographer, who’ll gently move an instrument called a transducer over your tummy. A special gel helps the transducer transmit ultrasound waves through your skin and a picture is created on a scan by soundwaves bouncing back off your womb and baby.

If you have a history of miscarriage, you’re experiencing bleeding or pain, or you’ve had fertility treatment, you may be offered an early scan between 6-11 weeks. You may also have a scan in the last three months if your baby is smaller than average; if you’re suffering from high blood pressure, diabetes or placenta praevia (a low-lying placenta); or if you’re expecting more than one baby.

Dating scan

This occurs between 10-13 weeks and will:

  • Look for your baby’s heartbeat.
  • View your baby’s skull.
  • Locate the placenta.
  • Confirm your dates. Up to 13 weeks, her length is measured from head to bottom (known as crown to rump). After that, a skull measurement is more accurate.
  • Check if there’s more than one baby.
  • Look at the thickness of the skin folds at the back of your baby’s neck (called the nuchal fold), your age and blood test information to estimate your risk of having a baby with Down’s syndrome or other chromosomal abnormalities.
  • If you’re expecting twins, check if they’re likely to share a placenta or have one each. A shared placenta means an increased risk of twin-to-twin transfusion syndrome.

Anomaly scan

This occurs between 18-20 weeks. It looks at your baby’s major organs and shows up any structural abnormalities. By this time, your baby’s sex is often clear but not all hospitals will tell you. If you want to know, ask your midwife about hospital policy. The scan operator will be looking carefully at the following:

  • Face – a harelip may be detected now. n Spine – for any signs of spina bifida.
  • Head – to check its shape and look at the brain. Some severe brain problems will be visible at this stage.
  • Limbs – to check the bones are present and for any signs of club foot.
  • Heartbeat and structure of the heart – to look at size and shape, though any holes in the heart would probably not be spotted now as they would be so small.
  • Kidneys – to check they’re not obstructed. n Stomach – to check it and the position of the umbilical cord.
  • Bladder – to look for any abnormalities.
  • The operator will also check the position of the placenta and see how much amniotic fluid is there.

Additional scans

Doppler scan

A Doppler scan looks at the health of your placenta by measuring blood flow through the umbilical cord. It’s usually done during the anomaly scan. If your baby is smaller than expected; if you have a condition that might affect blood flow like diabetes; or if you have a history of pre-eclampsia, you may need extra Doppler scans.

Nuchal fold translucency scan

This usually occurs between 10-13 weeks to screen for signs of Down’s syndrome, although it’s not available everywhere. It measures the amount of fluid between two layers of skin behind your baby’s neck (this is usually higher in babies with Down’s syndrome). If you’re high risk, the only way to get a firm diagnosis is by amniocentesis, which carries a small risk of miscarriage. For advice, call the charity Antenatal Results and Choices on 020 7631 0285 or visit www.arc-uk.org. If a nuchal scan is not offered, it’s possible to have one done privately for around £100.

  • To find out more about Down’s syndrome, call the Down’s Syndrome Association on 0845 230 0372.

What the new 3D/4D scans show

A routine scan lets you see a 2D image of your baby, but some hospitals have facilities for 3D scanning. It’s best done at 26-32 weeks because the baby is the right size to be seen clearly. A recent development is 4D scans, which takes a 3D video of your baby. Pioneered by obstetrician Professor Stuart Campbell, it can record a foetus ‘walking’ in the womb and yawning from as early as 12 weeks. Opponents argue it may result in more abortions, as it’s possible to spot minor abnormalities like a cleft palate early on, but Professor Campbell says the new scans are an important tool. In fact, he believes 4D technology can improve the bond between parent and child. ‘Maybe in the future it will also help us understand and diagnose genetic diseases, even conditions like cerebral palsy, which puzzles the medical profession as to why it occurs,’ he says.

‘From a technological point of view, the new scans are fantastic, but the relevance to antenatal care is yet to be established,’ says Dr Rob Hicks. ‘They may help bonding, but it’s hard to tell. It’s up to you to decide whether to pay for one.’ A private 3D or 4D ultrasound scan can
cost anything up to £275, depending on the package you choose. Check out www.babybond.com or www.babypremier.co.uk for details.

FAQs

What if there are signs of a problem?

he sonographer will tell you if she can’t find a heartbeat and will refer you for a second scan. For any other problems, though, she may just decide to contact your midwife or your obstetrician with the results

Why might I be offered another scan?

The baby’s position, the amount of fluid in your bladder, the position of your intestine and the state of your womb as it expands and contracts all alter the picture and affect the accuracy of the scan. This can make it difficult for the sonographer to be completely certain about possible problems. However, if your scan gives real cause for concern, you may be offered another one a little later.

Can I request another scan?

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A request for further scans has to come from a midwife or doctor. If you’re concerned about anything and feel you want another scan, speak to your midwife.

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