First Trimester Tests

Most women book with us for antenatal care during the first trimester. At your booking visit we will arrange a number of blood and other tests. We will also discuss second trimester tests that are available to screen for Down Syndrome. We have an ultrasound scanner in our clinic and can confirm that your due date is correct, check for baby's heart beat and confirm whether you are pregnant with one baby or with twins.

Your booking blood tests include:

A full blood count - This is to check for anaemia

Blood group and antibody screen - This is to check your blood group (A, B, O or AB) and rhesus group (positive or negative). Blood group antibodies that might interfere with cross matching blood for a transfusion or cause anaemia in a developing baby are also checked for.

Rubella serology - This is to check that you are immune to rubella (german measles). Most women have been vaccinated against rubella in their early teens but a few women will have little or no immunity.

Hepatitis B - This checks for infection or immunity to hepatitis B. Hepatitis B carriers can pass hepatitis onto their children and the babies of carriers are usually immunised shortly after birth.

VDRL - This screens for syphilis. This is now a rare disease but if detected treatment in pregnancy can prevent baby being infected.

HIV screening - HIV (the virus that causes AIDS) is still rare in pregnant women but carriers can infect their unborn child. Treatments are very effective in reducing this risk in women found to be carriers for HIV.

MSU (mid-stream urine) - A urine sample can check for unexpected urine infection or the presence of bacteria in your urine that increases your risk of kidney infections later in pregnancy.

Second Trimester Tests

Vaginal swabs - Infections such as Chlamydia, which often cause few or no symptoms, can be checked for in pregnancy though we usually wait until between 12 and 18 weeks to screen for this.

Anatomy scan - At 18 to 20 weeks of pregnancy most women have an anatomy scan. This is a detailed scan to check baby's brain, heart, spine and other important organs. The great majority of babies will be normal and couples find an anatomy scan very reassuring. Occasionally, an abnormality is detected and this can have important implications for your baby's care. For example, it may be necessary to arrange for baby to have a surgical procedure soon after birth. Some couples are very anxious that a severe abnormality will be found and a termination suggested. This is a very rare event and in most cases finding an abnormality can help paediatricians plan any treatment baby might need after it's born. It is also important to realize that not all problems and abnormalities will be detected.

It is often possible to tell if baby is a boy or girl but this is not the primary purpose of the scan. At best, the sonographer can only give you a strong idea about baby's gender. You may be offered a 4D ultrasound which produces very detailed pictures of baby but there is no particular medical reason to have a 4D scan.

Polycose test - this is done at about 26 to 28 weeks of pregnancy to check if you are at an increased risk of developing gestational diabetes. You will be given a sugary drink and an hour later some blood is taken. If your blood sugar is unexpectedly high you may need a further more detailed test called a Glucose Tolerance Test (GTT). For this test you will need to miss breakfast and then have blood taken before having a glucose drink and have more blood taken at one and then two hours later.

Gestational diabetes is associated with high blood sugars in pregnancy. Exposure to high sugar levels can result in baby becoming excessively large. Women who develop gestational diabetes are also at greater risk of developing diabetes in later life.

Blood group antibody screen, full blood count and ferritin levels - These are also checked at the same time as your polycose test to look for signs of anaemia and the development of antibodies to baby's blood group.

Third Trimester Tests

Ultrasound scans - If there is a concern that your baby is too small or large we will organise an ultrasound scan to check that your baby is growing appropriately. Most women will not need any ultrasound scans after their 18 week anatomy scan. A few women may need several scans to monitor all is well with baby. If you go past your due date then ultrasounds scans will be arranged to check that there is still plenty of fluid around baby.

Cartiotocographs (CTG) - Sometimes in late pregnancy it is important to check all is well with a CTG machine that monitors baby's heart beat and movement. This is particularly helpful if you are still pregnant after your due date or there are worries about baby's movements.

Blood tests - Don't worry - most women don't need any blood tests after their polycose test. Women who are rhesus negative or have blood group antibodies will usually have further tests at 34 weeks. Women with blood pressure problems or medical problems may need regular blood tests especially towards the end of their pregnancy.

Screening for Down Syndrome

Both ultrasound and blood based tests are available to screen for Down Syndrome. The results of these two types of tests can also be combined in an integrated test. All three tests give their result as a risk (for example 1in 500 or 1 in 2000). Many couples find their screening options confusing. We are here to help you understand the options that are available to you.

Couples who find out they are going to have a child with Down Syndrome will often decide to have a termination but for other couples, continuing with their pregnancy is the right decision. It is important that you consider what choices you might make yourself when embarking on any screening programme. We all feel our role at AOC is to support couples in their decision making and provide information to help them.

What is Down Syndrome? - A normal child has 23 pairs of chromosomes. A child with Down Syndrome has an extra twenty first chromosome (the condition is sometimes called Trisomy 21). This is the result of an abnormality arising at the moment of conception. Why it occurs is unknown. It becomes commoner with increasing maternal age. For example at 30 a woman has a one in 350 chance of carrying a baby with Down Syndrome when she has a screening scan at 11 to 14 week. At 40 this rises to one in 100. Children with Down Syndrome have a varying degree of intellectual disability. Some have other serious medical problems but many children with Down Syndrome will lead fulfilling lives. For more information look at the websites listed on our useful websites page.

The Nuchal Translucency Scan - This is arranged for between 11 and 14 weeks of pregnancy. The thickness of a layer of fluid under the skin at the back of baby's neck is measured. Babies with Down Syndrome tend to have a slightly thicker fluid layer than other babies possibly because of how lymph fluid is drained under their skin.

This measurement is combined with your age related risk to produce a personal risk for you. This is an ultrasound based test and is completely safe. No x-rays are used.

The scan can also recheck your due date, confirm a heart beat is present and occasionally pick up other abnormalities in baby.

Serum Test - This is a blood test done at 14 to 18 weeks of pregnancy. The concentrations of three hormones are measured. These levels tend to be slightly different in women carrying a baby with Down Syndrome. These results and your age are combined to give you a personal risk for carrying a baby with Down Syndrome.

Integrated Screening - The results of a nuchal translucency scan and serum test can be combined to produce a more accurate assessment of your personal risk of having a baby with Down Syndrome. The integrated test will pick up more babies with Down Syndrome and allow more women to avoid an amniocentesis than just the nuchal scan or serum test on their own.

Older women sometimes prefer to proceed straight to amniocentesis but it is important to realise that even women in their early forties will frequently find that their screening test results are sufficiently reassuring that they decide not to have an amniocentesis.

Amniocentesis - This test is usually done at between 15 and 17 weeks of pregnancy. A needle is passed through your abdominal wall into the fluid around baby - an ultrasound scan is used to guide the needle and make it a safe procedure for baby. Local anaesthetic can be used to make it a more comfortable procedure for you. A small amount of fluid is drawn off. Within this fluid are some of baby' s skins cells that can be cultured in the laboratory to check the chromosomes. It can take 10 to 14 days to get a result from this test. A more rapid test (called FISH) is available that can check for Down Syndrome within 24 to 48 hours is also available but at an additional cost - the doctor performing your amniocentesis can discuss this option with you.

Amniocentesis is a quick procedure taking about 10 to 15 minutes to set up and only a few minutes to do. You are welcome to bring your partner or a support person along and should plan to have a quiet 24 hours after the test. It does have a small risk of miscarriage. For every 150 women having an amniocentesis one woman will miscarry as a result of the procedure.

Chorionic Villus Sampling - This is similar to amniocentesis but it can be done a couple of weeks earlier in pregnancy. A small piece of tissue is obtained from baby’s placenta using a similar needle to the one used for an amniocentesis. Technically it is more difficult to do with possibly a slightly higher rate of miscarriage. It tends to be done in women with a particularly high risk of having a baby with a chromosomal abnormality.

For most couples, decision making around Down Syndrome screening is straightforward with all their results being very reassuring. All of us at AOC are aware that for some couples making these decisions is terribly difficult - we are very happy to talk to you by phone between appointments or arrange extra visits to clinic if you need more help in deciding what tests to have.

Useful sources of information - We can provide you with written information to help guide your decision making. Useful websites are also listed on our websites and information page.