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First Trimester ultrasound scan & screening: 11 - 14 weeks

 

Your midwife will have offered you a First Trimester Screening Clinic Booklet, discussed what screening tests are offered including attendance at the First Trimester Screening Clinic (FTSC).

 

Why do I need an ultrasound scan?

We offer an ultrasound scan between 11 and 14 weeks of pregnancy to:

What will happen at my ultrasound scan appointment? 
Scans are carried out by specially trained doctors or sonographers.  Exeter is a teaching hospital and some scans may be performed by a trainee under supervision.

 

Please inform staff if you do not wish a trainee or student to be present.
The scan image will be best viewed in a room that is dimly lit.

 

You will first be asked to lie on a couch and raise your top to your chest and lower your skirt or trousers to your hips. Tissue paper will be tucked around your clothing to protect it from the ultrasound gel. (The gel makes sure there is good contact between the machine and your skin.)

The sonographer passes a hand-held device called a probe over your skin. It is this probe which sends out ultrasound waves and picks up the echo when they bounce back. The sonographer will carefully examine your baby. Scanning requires a lot of concentration, especially if your baby is active.

 

Having the scan does not hurt, but the sonographer may need to apply slight pressure to get the best views of the baby. A black and white picture of the baby will then be seen on the ultrasound screen. Most examination take about 20 minutes but occasionally you may be asked to wait longer to allow your baby to move into a more favourable position
FTSC ultrasound scan appointment in pictures 

 

Should I have the test for Down’s Syndrome?
Only you can decide that. Some women want to find out if their baby has Down’s syndrome and some do not.

Click here for the testing for Down's syndrome during pregnancy picture leaflet

 

How do you test for Down’s Syndrome?
We begin by offering all women a test that carries no risk of miscarriage. This type of test is called a screening test. Screening does not give a definitive answer, it does help to tell us which babies have an increased chance of having Down’s Syndrome. At the clinic you can choose to have the combined test for Down’s syndrome that involves an ultrasound scan and a blood test.

 

The scan establishes the size of your baby by measuring the Crown Rump Length ( CRL). If the CRL is between 45-84mm, we can offer a combined screening test. If the CRL is over 84mm, it is too late for combined screening but we may be able to offer you a second trimester blood test (quad test).

 

As part of the ultrasound, we will try to measure the Nuchal Translucency (NT) provided your baby is lying in a suitable position. The NT is a thin film of fluid under the skin at the back of the neck. Babies with Down’s syndrome often have an increase in fluid at the back of their neck.

 

After the scan, a blood sample is taken from the mother’s arm. The results of the blood test are combined with the CRL, NT, mother’s age, weight, smoking status and ethnicity to work out the chance of your baby having Downs Syndrome. Other details could be relevant in the calculation. Please tell us if you have had a previous pregnancy with Down’s syndrome or fertility treatment

 

How long does it take to get the results of my Down’s syndrome screening test?

 

The combined test is usually calculated within two working days.
The quad blood test takes approximately 1 week.

Test results with an increased chance of having Down’s are telephoned to the mother and so it is very important that we have a contact telephone number. Low chance results will be sent out in the post.

 

What happens if I have a increased chance result?
If the result of the screening test shows the chance of your baby having Down’s syndrome is greater than the Trust’s cut -off figure we will offer you a diagnostic test.

This carries no risk to your pregnancy but leaves some uncertainty until after you’re a baby is born.

This will give you a definite result but carries a small risk of miscarriage

There are two diagnostic tests for Down’s syndrome

You will be offered more information about these if you have an increased chance result.

 

What are the routine blood tests?
As an important part of your antenatal care you will be offered a number of blood tests. These help protect the health of you and your baby.

An important part of this test is to establish the level of haemoglobin (Hb) in your blood. If your Hb is low you are said to be anaemic and you may feel tired or dizzy. This is caused by a lack of iron in your blood and you may be prescribed iron tablets and advised to eat an iron rich diet.

It is important to know what blood group you are. Rhesus is the name given to a special protein. If you have this protein you are rhesus positive and if not you are rhesus negative. We now recommend that all rhesus negative women receive Anti-D during pregnancy.

This test is to ensure you are immune to rubella.

This is a sexually transmitted disease that can be passed from mother to baby.

Hepatitis B is a virus that causes inflammation and infection of the liver and may lead to permanent damage. It is possible to carry the virus in your blood without having any symptoms. Women who are carriers can pass the virus to their babies during birth.

You may be offered some additional blood tests depending on your ethnic background or medical history. These include Sickle cell disease, Thalassaemia and Hepatitis C.

Please see our First Trimester Screening Clinic Booklet for further information on all these blood tests

Call 111 when its less than urgent