FIRST TRIMESTER
FOCUS ON
Scans
Dr Chiara Hunt AND Marina Fogle DISCUSS THE VARIOUS SCAN OPTIONS AVAIL ABLE THROUGHOUT YOUR PREGNANCY eeing your baby at any of your scans is an unforgettable moment. During your pregnancy, you’ll have two main scans: the 12-week check-up and the 20-week scan – both performed using ultrasound. Ultrasound scans have been used in pregnancy since the mid-1950s and have no known side effects for mother and baby. They’re a really good way of having a non-invasive yet detailed look inside the uterus at the developing fetus. It’s now widely accepted that due dates predicted from scans are the most accurate. Of course, if you’ve had IVF and know the precise date of implantation, you will know exactly. If you believe you know because ‘it could only have happened on one night’, remember that sperm can live for up to seven days, so fertilisation can occur on the day you have sex (if you happen to ovulate that day) or a few days later. It’s fairly common for your due date to be recalculated after your scan, and it might have changed by up to a week or so. The scan date is more accurate, but do bear in mind that your baby is likely to arrive anywhere between three weeks before and two weeks after that date. It’s important to remember that, although the scans are good, they don’t always detect every abnormality. A normal scan, although reassuring, doesn’t give a 100 per cent clean bill of health. For example, of the one per cent of babies born with a heart abnormality, about half of these are picked up at birth or later. The scans only look at the structure of the organs; they can’t give us much information about their function; this can be more
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carefully assessed after the baby is born. Although for many this is a happy experience, for an unlucky few the 12-week scan is when they’ll find out they’ve had a miscarriage, so it’s normal to feel both nervous and excited. And while you may have to follow new Covid-19 guidelines, you can be rest assured that you will have all your necessary scans.
THE 12-WEEK CHECK-UP (NUCHAL SCAN) The 12-week check-up is really important. Using a combination of ultrasound and a blood test, it determines the risk of the fetus having a chromosomal abnormality, such as Down’s Syndrome, as well as many other things, including genetic syndromes and structural abnormalities. The ultrasound scan checks the fetus is growing well, but another purpose is to look at the translucent, or clear, space in the tissue at the back of your fetus’s neck – hence, the name ‘nuchal scan’. The baby’s nasal bone is also measured. Babies with abnormalities tend to accumulate more fluid behind the neck and have absent nasal bones. Sometimes this scan is also called the ‘dating scan’, as it accurately predicts the due date more so than dating from your last period. In order for the tests to be accurate, the check-up must be done between 11 and 14 weeks. It doesn’t give you a diagnosis of any abnormalities, simply an idea of whether you are at high or low risk of certain conditions. If the risk is deemed high, you may be advised to have chorionic villus sampling (CVS) or amniocentesis tests; these are the only
EXTRA SCANS There are many other scans and tests available privately. Here are your options: • Fetal viability scans, at six to 10 weeks, will check that the embryo has implanted correctly and, from seven weeks, you’ll be able to hear a heartbeat. This scan is often done internally. Cost: approx £100. • 3D scans show still images of your baby in three dimensions. 4D scans show moving 3D images of your baby. Parents will see baby’s skin, rather than her insides. You may also be able to see the shape of your baby’s mouth and nose. The best time to have either of these is between 26-30 weeks. Cost: from £50. • There’s mounting pressure for late scans to be included routinely in NHS care, but currently, unless there are problems, your final scan would be at weeks. A late scan will check that the baby is growing nicely and that the placenta looks healthy and is working properly and will measure the amount of amniotic fluid. octors might also do a oppler scan to check the blood flow in the umbilical cord. Cost: approx £150.
