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Find out more about the 20-week screening scan (also called the anomaly scan), which looks for 11 different conditions in your baby. Find out how to get it, what happens during the test and when you get the results.
The 20-week scan is done to check if your baby could have a condition that affects their health and development.
Your baby will be checked for signs of 11 different conditions as part of the scan.
Some conditions can be seen more clearly than others, so the scan may not find everything. But screening is the best way to find any conditions, and help you and your doctors make the best decisions for you and your baby.
Your placenta and the blood flow in your uterus will also be checked.
A 20-week scan is always offered when you're pregnant. It's usually done when you're between 18 and 21 weeks pregnant.
Your midwife will tell you how to book the 20-week scan. How you book depends on which area of the country you are in.
You may:
You'll usually have the scan before you're 21 weeks pregnant, but you're able to have it up until you're 23 weeks pregnant in some cases.
You'll also be told if you need to have a full bladder before the scan.
If you've not had a 20-week scan and you're between 18 and 23 weeks pregnant, tell your midwife or GP.
It's your choice if you want to have a 20-week scan or not. The scan is the best way to find out if your baby has one of the 11 conditions, but not everyone wants this information. Talk to your midwife about your options.
If you decide not to have it but change your mind later, speak to your midwife or GP. They can tell you if you're still able to have the scan.
There are things you can do to prepare for your 20-week scan.
arrive for your appointment early
wear loose clothing that's easy to move to get to your tummy
take out a belly piercing, if you have one
bring your maternity notes with you, if you have paper notes
make sure you have a full bladder before the scan, if you've been told to
check with the hospital or clinic before your appointment if you'll need to pay for pictures of your baby
You can bring someone to the scan with you, but most hospitals do not allow children. Check with the clinic or hospital before your appointment.
Your 20-week scan is usually done at a local hospital, clinic or health centre by a trained healthcare professional.
The ultrasound scan usually takes around 30 minutes. There's no known risk to you, or your baby, from the scan.
The scan can sometimes take longer if your baby is moving around a lot or is not in the right position to get clear pictures.
If this happens, you may be asked to go for a walk or eat something before coming back after a short break so all the checks can be done.
If it's still difficult to get clear pictures of your baby, you'll be offered another appointment before you're 23 weeks pregnant.
The scan cannot find all conditions. If you have any symptoms you're worried about or something does not feel right, it's important to tell your midwife.
You'll be told the results of the 20-week scan after the healthcare professional has done all the checks.
Most people will be told their baby does not have any signs of a condition.
But some people may be told their baby has signs of one of the conditions being checked for.
You'll be told if there are signs your baby may have a health condition after the scan.
If the ultrasound scan finds something, you may be offered more scans and tests, such as amniocentesis or chorionic villus sampling.
You'll be referred to a specialist, who will tell you more about the tests to help you decide if you want to have them.
These tests will be able to tell you if your baby definitely has a health condition and what this means for you and your baby.
Find out more about what happens if antenatal screening tests find something and about having a baby that might be born with a condition.
Antenatal Results and Choices (ARC) has information about screening tests and how you might feel if you're told your baby has, or might have, a condition.
Their helpline is open Monday to Friday, 10am to 5.30pm.
Call 020 7713 7486.
It's important to continue taking any medication prescribed unless your GP/specialist specifically tells you to stop. Please visit our Existing Health Conditions page for more information, or visit 'Bumps' ('Best Use of Medicines in Pregnancy').
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