12-week scan

You're approaching the end of your first trimester and, if you're lucky, might even be leaving morning sickness behind you and glowing with health like only a pregnant woman can. It's also time for your 12-week scan. Make sure you arrive at yours knowing exactly what to expect, so you get the most out of your appointment.

When will I have my first scan?
The NHS usually offers two scans during pregnancy - at around 12 weeks and 20 weeks. If you've had a miscarriage before, or you experience bleeding in the first weeks of pregnancy, the first scan may be brought forward to between six and 10 weeks. But if there are no concerns, then the 'dating scan' should take place between 11 and 13 weeks. The timing can vary depending on the area you live in, so it's best to check with your GP in advance. You will be referred to the nearest hospital where sonographers have the appropriate training.

What does an ultrasound feel like?
You'll be asked to lie on a bed so that a conductive jelly can be applied to your bump. A probe sending soundwaves into your womb is then passed backwards and forwards over your tummy. The sound is reflected back and creates a picture, which is shown on a monitor. Remember to drink lots of water before you have this scan, as a full bladder pushes your womb up to give a clearer picture. It is not possible to accurately determine the sex of your child at this stage, so if you want to know, you'll have to wait until your mid-term scan. This is a really special moment for both you and your partner, as seeing your baby for the first time makes your pregnancy suddenly real! Remember to take along some cash - it's possible to have pictures of your scan, but there may be a small charge.

What will the sonographer be looking for?
Argyro Syngelaki, sonographer at King's College Hospital, says, 'The 11-13 week scan is done for several reasons: to date the pregnancy accurately, to confirm multiple pregnancies and to ensure the baby is developing properly. We will be able to diagnose any foetal abnormalities by examining all the structures of the body. We will also determine the risk of Down's syndrome and other chromosomal abnormalities. We do this using ultrasound and a blood test.'

What tests will I be offered?
The nuchal fold translucency test is the most accurate way of screening for Down's syndrome and will be carried out during this scan. There are two layer of skin behind your baby's neck (the nuchal fold) and the amount of fluid accumulated there, which appears as a black space on the screen, is measured using ultrasound. Foetuses with higher levels of fluid tend to be more at risk of being born with Down's. The measurements can also identify major congenital heart problems. This test is usually offered alongside a blood test, which looks for the presence of certain hormones produced by the placenta. Favourable levels of these will reduce the risk of your baby having Down's. These results, along with your age and your baby's heart rate can then be used to assess the chances of your baby having a problem when born.

Argyro says, 'After the screening test, parents may choose to have a diagnostic test if they consider that the chance of the baby being affected is high. There are two tests, chorionic villus sampling (CVS) or amniocentesis. However, these tests are invasive and can result in miscarriage. There is about a 1% risk from either procedure.'

Both tests involve the insertion of a long thin needle into the abdomen. With amniocentesis, where you need to be at least 15 weeks pregnant, a small amount of the amniotic fluid surrounding your baby is removed, while with CVS, which can be carried out as early as 11 weeks, a similar method is used to obtain a tissue sample from your placenta. If you prefer, this tissue can also be collected via a catheter threaded up into the cervix.

For more advice, visit our scans and checks channel.

Babyexpert.com 27/02/2012 10:56:00
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1 comments on this
Silver member

21/08/2013 at 19:31

Please be aware that in Wales, they do not do the nuchal fold translucency test as part of the 12 wk scan, I found this out too late and ended up paying privately for a quad test which is the nearest test on offer post twelve weeks as opposed to putting yourself through an amniocentesis which carries risks in itself. Because it is not part of the NHS test in Wales your midwife may not explain this to you, if you are at higher risk of DS because of age etc like I was, please ask the question BEFORE 11 weeks so you can arrange it privately if you want to, as there is a window of opportunity
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