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Tests and Screening in Pregnancy

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  • Antenatal Tests

    • During your pregnancy you will be offered a range of tests designed to check and assess the development and wellbeing of you and your baby.
    • These include; urine sample, height and weight, blood pressure and blood tests. These can all provide reassurance about the progression of your pregnancy as well as help identify any problems that you may be experiencing.
    • You do not need to have any of these tests, however it is important that you understand what the tests are for, so you are able to make an informed decision about your care. Your midwife will be able to answer any questions that you may have.
    • Here is a useful link to the NHS choices website regarding antenatal testing
    • Antenatal checks and tests - NHS (www.nhs.uk)
  • Ultrasound Scans

    • You will routinely be offered two scans, the dating scan at 8-12 weeks which will determine the baby's due date and the anomaly scan at about 20 weeks.
    • Ultrasound scans use sound waves to build a picture of the baby in the uterus. The scans are painless, have no side effects on mother and baby and can be carried out at any stage of pregnancy.
    • At the dating scan, the sonographer will check your baby's measurements and be able to give you your baby's estimated date of delivery (EDD). It will confirm a single baby or if you are carrying twins as well as the position of the placenta.
    • You will be asked to have a full bladder, this pushes your uterus up and gives a better picture of baby. Scans are medical procedures but many women see them as the highlight of the pregnancy.
    • The anomaly scan checks the physical development of your baby, although it can't pick up every condition. It will look in detail at the baby's bones, heart, brain, spinal cord, face, kidneys and abdomen, checking for 11 rare conditions.
  • Screening

    • Here is a useful video about screening
    • Testing for Downs syndrome, Patau and Edwards syndrome
    • Between 10 and 14 weeks you can have "the combined test".  You will be offered a blood test and at the dating ultrasound scan the fluid at the back of your baby's neck will be measured (known as the nuchal translucency). The information from these 2 tests is combined to work out the chance of your baby having Down's syndrome, Edwards' syndrome or Patau's syndrome.
    • If you are further along in your pregnancy you will be offered a blood test called the "quadruple test" usually between 14 and 20 weeks of pregnancy. The quadruple test is not quite as accurate as the combined test.
    • The results of the test cannot tell you if your baby definitely has Down's syndrome, Edwards' syndrome or Patau's syndrome, it will give you a risk ratio which will determine if you are high or low risk for a pregnancy with any of these conditions.
    • You can choose to have the screening test for all three conditions, or just for Down's syndrome, just for Edwards and Patau's syndrome or decline them all.
    • You will get two results, one for Down's syndrome and a joint one for Edwards' syndrome and Patau's syndrome.
    • If the test shows the risk of the baby having Down's syndrome, Edwards or Patau's syndrome is lower than the recommended national cut-off, this is known as having a 'low-risk' result, but it does not mean there is no risk.
    • If you have a high risk result, you will be offered a diagnostic test to find out for certain whether or not your baby has Down's syndrome, Edwards' syndrome or Patau's syndrome.
  • Diagnostic testing

    • Diagnostic tests for Down's syndrome will also look at chromosomes 18 and 13, so will also tell you whether or not your baby has Edwards' syndrome or Patau's syndrome. Similarly, diagnostic tests for Edwards' syndrome and Patau's syndrome will also look at chromosome 21 for Down's syndrome.
    • Video Screening tests for you and your baby: https://youtu.be/_afr5olIpTM
    • In a small portion of women who elect to have the diagnostic test approx. 1 out of 200 women (0.5%) will miscarry as a result of the test. It is up to you whether or not to have the further test.
    • There are two types of diagnostic tests:
    • Chorionic villus sampling
      • Chorionic villus sampling (CVS) is usually done from 11 to 14 weeks of pregnancy. A fine needle, usually put through the mother's abdomen, is used to take a tiny sample of tissue from the placenta. The cells from the tissue are then tested for Down's syndrome, Edwards' syndrome and Patau's syndrome.
    • Amniocentesis
      • Amniocentesis is usually done after 15 weeks of pregnancy. A fine needle is passed through the mother's abdomen into the uterus to collect a small sample of the fluid surrounding the baby. The fluid contains cells from the baby, which are tested for Down's syndrome, Edwards' syndrome and Patau's syndrome.
      • After finding out the results of the diagnostic testing a small number of women who have the diagnostic test will find out their baby has one of the conditions.
      • Prior to and following, any diagnostic testing you will counselled by one of the Obstetricians. They will be able to discuss with you the risks of the procedure as well as the outcome of the tests, and what your options would be going forward.

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