Maternity Service
Saint Mary’s Hospital
Tests for you and your
baby during pregnancy
Contents
Page
What is this leaflet about?
3
Routine blood tests for the mother
4
•
Anaemia
4
•
Blood group
4
•
German measles (rubella)
4
•
Syphilis
4
•
Hepatitis B
4
•
HIV and AIDS
4
•
Thalasseamia and sickle cell anaemia
4
•
Dating scan
5
•
Anomaly scan
6
•
Downs Syndrome
7
•
Spina bifida
12
•
Twins or triplets
12
Information about other tests that may be relevant
to some pregnant women
13
•
Immunity to chickenpox
13
•
Glucose tolerance test
13
•
Amniocentesis
14
•
Chorionic Villus Sampling (CVS)
16
•
Comparing amniocentesis and CVS
17
A quick guide to testing in pregnancy
17
What if something is wrong with your pregnancy?
19
Useful contact numbers
19
2
What is this leaflet about?
Most women will have normal healthy pregnancies and the great majority of babies
will develop normally in the womb. During pregnancy women are offered a range
of tests which are designed to check whether the baby is developing normally and if
the pregnancy is going well. This leaflet has been produced to help pregnant women
and their families to decide whether or not to have the tests that are offered during
pregnancy. These tests help to discover some problems that may occur with the
pregnancy or the baby.
You can choose whether to have these tests or not. You may choose to have some
but not others. Before you have any tests it is important that you think carefully
about them. Think about how you would feel if the result was normal, but, more
importantly, think about how you would feel if the result was abnormal – what
would you do then?
All tests and investigations are optional.
What sorts of tests are there?
There are three types of tests – they are:
•
Routine blood tests for the mother
These check your general health.
•
Screening tests
These tell you whether you have an increased chance (risk) of your baby
being born with a condition such as Down’s syndrome or heart problems.
These can either be blood tests or ultrasound scans. They do not give you
any definite answers, they simply tell you how likely a problem is.
Screening tests are not foolproof. They can sometimes miss problems or find
unexpected ones.
•
Diagnostic tests
These tests are offered to women who have an increased risk of having a
baby with a problem. We may know that they are at increased risk because
of the result of a screening test, or because of a woman’s age or because of
previous problems.
Diagnostic tests give a definite answer as to whether a problem is present or
not. However, with diagnostic tests such as amniocentesis, there is a small
chance of causing a miscarriage to a healthy baby.
The first half of this booklet gives you information about the routine tests normally
offered in pregnancy. The second half covers, in more detail, some of the tests
offered to particular groups of pregnant women.
Your midwife, GP or the hospital staff are happy to talk to you about the tests and
answer any questions you may have. They will support you in whatever choice
you make.
3
Routine blood tests for the mother
A number of tests will be offered at your first contact with your community midwife
or at the hospital visit, and some of these will be repeated at later visits. They are all
done to assist in maintaining your health and well being during pregnancy. The
Department of Health recommends that all pregnant women are offered these tests.
These may include tests to see:
• Whether you are anaemic
If you are anaemic you will probably be given iron and folic acid tablets to take.
Anaemia makes you tired and less able to cope with losing blood at delivery.
• Whether your blood group is Rhesus positive or negative
A few women are Rhesus negative. Rhesus negative women occasionally develop
complications which make their baby anaemic and jaundiced. This complication
can be prevented by giving injections at certain times during the pregnancy. It is
therefore important to find out whether you are Rhesus negative. If you want to
know more about this your midwife can give you a leaflet which will explain it in
more detail.
• Whether you are immune to German measles (rubella)
If you get German measles early in pregnancy it can seriously damage your
unborn baby.
• Whether you are affected by Syphilis
It is important to detect this infection as soon as possible in pregnancy.
Treatment with antibiotics will cure the infection and prevent it from causing
long term problems in your baby.
• Whether you are affected by Hepatitis B
This is a virus which can cause liver disease. If you carry the hepatitis B virus it is
likely that you could pass it on to your baby at birth. The good news is that there
is a vaccine which can be given to your baby to protect him/her. If you are a
carrier of hepatitis B, we will let you know so that you and your family can have
the right follow up care.
• Whether you are affected by HIV
This virus can be passed from mother to baby during pregnancy. If the mother
carries the virus, treatment can be given to reduce the risk of her passing it on to
the baby. If you are affected by HIV, specialist care is available for you and your
baby. There will also be the opportunity for your partner and family to be tested.
• Whether you have Thalassaemia and sickle cell anaemia
Thalassaemia and sickle cell anaemia are two serious blood disorders that can be
inherited (run in the family). Although these blood disorders are more common
in people from Asia, Africa and the Mediterranean countries we offer testing for
these blood disorders to all women.
For a baby to have either thalassaemia or sickle cell anaemia it needs to inherit
two genes for the disorder, one from its mother and one from its father. A simple
blood test can show whether you have one of these genes. If we receive a result
which needs further investigation, we will refer you and the baby’s father to the
Thalassaemia and Sickle Cell Centre and they will send you an appointment.
4
How will I get the results?
You will usually receive all the results of the tests you have consented to at your
16 or 20 week visit or by letter. If they are abnormal you may be informed by
letter sooner.
Dating scan
All women who book for delivery at Saint Mary’s Hospital will be offered a dating
scan. You will be given information about the scan when you first meet your
midwife in the community and or at the booking visit. At these appointments you
will be given a leaflet ‘Having an Early Pregnancy scan’ which will explain how and
why the scan is done. The scan will be performed after your booking appointment
(usually between 8 and 14 weeks of pregnancy) when you have had time to read the
leaflet and decide if you wish to have it. If you have had a scan before attending for
the booking appointment and it showed that you were more than 8 weeks pregnant
then another scan is not usually offered.
How is the scan done?
You need a full bladder as this helps us get a better view. You will be asked to lie on
a bed. The person doing the scan will put some jelly on your tummy and then rub a
smooth probe (the scan ‘camera’) over your tummy, which relays images to a screen.
It does not hurt you and it does not harm your baby. It takes about 10 minutes.
Why is this scan done?
You can choose whether or not to have a scan, but these are the main reasons
why it can be useful:
•
To check the baby’s heartbeat. Some women unfortunately miscarry early
in the pregnancy without realising it. An early scan can reassure most women
that all is well.
•
To count the number of babies. Women with twins or triplets need to be
monitored more closely during their pregnancy. If you are having twins or
triplets it is better if we find out sooner rather than later.
•
To measure the baby to check when the baby is due. If you are
considering having the combined screening for Down’s syndrome, the dating
scan and the Nuchal translucency scan may be done at the same time. (see
page 9). If you decided that you did not want the test for Down’s Syndrome
then a dating scan only wold be done.
Although this first scan would not usually pick up problems with the
development of baby, they are sometimes noticed at this early stage.
If a problem was found your doctor would discuss it with you.
The scan may not be as clear if women have an increased Body Mass Index
(are overweight) or when the baby is in a certain position.
Can I buy a photograph?
You can buy a photograph of the scan. It costs £3 and you will need three £1 coins
for the machine.
Can I take a video/DVD?
No. This is not possible at Saint Mary’s Hospital.
5
Anomaly scan
You will be offered a scan between 18 weeks and 20 weeks plus 6 days into your
pregnancy. This scan is used to check whether your baby is developing normally, or
whether it has any obvious abnormality. You will be given information about the
scan when you first meet your midwife in the community and or at the booking visit.
At these appointments you will be given a leaflet ‘Having an 18 to 20+6 weeks Fetal
Anomaly scan’ which will explain how and why the scan is done. This is given early in
your pregnancy to give you time to read the leaflet and decide if you wish to
have it. If you decide not to have the fetal anomaly scan you will be offered a scan
at 32-34 weeks to check the baby’s growth and placental site. Sometimes obvious
abnormality may be detected even though we were not checking for it.
How is the scan done?
The scan is done in the same way as the dating scan. You will need to have a full
bladder to help us see things clearly. It takes about 20 minutes. Sometimes the scan
may need to be repeated if we can’t see everything clearly.
What happens if a problem is picked up?
Most babies look normal on the scan but sometimes a problem is picked up. If there
is a problem seen on the scan your doctor will explain this to you. The problems
identified on scan range from minor problems to very serious problems.
•
Many of the problems we identify on scan are relatively minor, and simply
need following up by further scans during the pregnancy and after delivery.
•
Sometimes further tests may be offered to get more information.
•
With some problems the scan helps you and your doctors to prepare for
the birth of a baby which may need special treatment after delivery.
•
Occasionally a very serious problem may be picked up on the scan. In this
situation some parents may feel that they would not want to continue with
the pregnancy and ending the pregnancy would be an option. Other parents
would choose to continue with the pregnancy. In this situation we would
want to ensure that you had all the information before you made
a decision about your pregnancy. You would not be rushed into making a
decision and we would support you fully in whatever you chose to do.
•
The scan may not be as clear if women have an increased Body Mass Index
(are overweight) or when the baby is in a certain position.
Who can I bring with me?
You can bring one person to the scan with you. It is important to remember that
this is an important test to check whether your baby is normal. It is important not to
distract the person performing the scan, so that they can concentrate on checking
your baby carefully.
Can I buy a photograph?
After your baby has been checked, you will be shown your baby on the screen and
you can buy a photograph of the scan. It costs £3 and you will need three £1 coins
for the machine.
Can I take a video/DVD?
No. This is not possible at Saint Mary’s Hospital.
6
Are all problems picked up?
No. Only seven out of ten problems are picked up on scan. This means that some
babies can be born with problems even when the scan appeared normal. These
include conditions such as Down’s syndrome, heart problems and problems in the
baby’s development that occur later on in pregnancy. Some problems are easier to
detect than others. The baby will not be seen as clearly in women who have an
increased Body Mass Index (overweight) or when the baby is in certain positions.
The table below shows how easy or difficult it is to pick up the different problems.
Problem
What the problem is
Chance of being seen
Spina bifida
Open spinal cord
90%
Anencephaly
Absence of the top of the head
99%
*Ventriculomegaly
Excess fluid within the brain
60%
*Major heart problems
25%
*Diaphragmatic hernia
A defect in the muscle which
separates the chest and abdomen
60%
Exomphalos/gastroschisis
Defects of the abdominal wall
90%
Major kidney problems
Missing or abnormal kidney
85%
Major limb abnormalities
Missing bones or very short limbs
90%
Cerebral Palsy
Spasticity
Never seen
Autism
Never seen
*Many cases present late in pregnancy or even after birth
Ref RCOG Routine Ultrasound Screening in Pregnancy Protocol, Standards and Training London 2000
What is Down’s Syndrome?
The word syndrome means a collection of characteristics. Although people with
Down’s Syndrome all have their own individual characteristics, they also have
physical features shared by others with Down’s Syndrome.
People with Down’s Syndrome also have learning difficulties. About half of all babies
born with Down’s Syndrome will have a heart problem or a problem with the bowel,
and more than half have significant hearing problems or problems with their sight.
Some of these babies will die very young, but many will have a
normal length of life.
In the UK about 600 babies are born with Down’s Syndrome each
year. It occurs in families from all social, cultural, religious and
racial backgrounds. However, the chance of having a baby with
Down’s Syndrome increases as a mother gets older.
7
This chart shows what chance women of different ages have of
giving birth to a baby with Down’s Syndrome
Age of the mother
Risk of Down’s Syndrome
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
1 in 1527
1 in 1507
1 in 1482
1 in 1448
1 in 1406
1 in 1352
1 in 1286
1 in 1206
1 in 1113
1 in 1008
1 in 895
1 in 776
1 in 659
1 in 547
1 in 446
1 in 356
1 in 280
1 in 218
1 in 167
1 in 128
1 in 97
1 in 73
1 in 55
1 in 41
1 in 30
1 in 23
Ref Cuckle et al, 1987
How does it occur?
Our bodies are made from millions of cells which are too small to be seen
with the naked eye. Every cell contains chromosomes, which carry the recipe,
or blueprint, for all the characteristics we inherit. Normally there are 46
chromosomes, but a baby with Down’s Syndrome has an extra chromosome,
making 47 in total. This results in a disruption to the growth of the developing baby.
Can I have a test to find out if my baby has Down’s syndrome?
There are several different tests available for Down’s Syndrome. The tests are offered
because some women would choose to have a termination (abortion) if they knew
that the baby they were carrying had Down’s Syndrome. Others may just wish to be
prepared for the birth of a baby with Down’s Syndrome. You will have your own
views on what you would wish to do.
Before you have a test it is important that you think carefully about it. Think
about how you would feel if the result was normal, but more importantly
think about how you would feel if the result was abnormal
– what would you do then?
8
Screening test for Down’s syndrome
The screening tests that we routinely offer at Saint Mary’s Hospital are the combined
test and Quadruple test.
• Combined test (Nuchal Translucency scan and a blood test)
A Nuchal Translucency scan measures the amount of fluid under the skin at the
back of the baby’s neck and the blood test measures the levels of two hormones
in your blood. We use this information together with your age and weight to
estimate the chance of your baby having Down’s syndrome. If the chance was
more than 1 in 150 we would say that this is an increased chance. If the chance
was less than 1 in 150 we would say that this is a low chance.
The test can be performed between 11 weeks and 2 days and 14 weeks and 1
day of pregnancy. We would aim to perform this test at about 12 weeks of
pregnancy. This test will be offered to you if you book for care early in
pregnancy. If the sonographer is unable to measure the fluid at the back of the
baby’s neck you will be offered an alternative test – the quadruple test which has
a similar detection rate for Down’s syndrome. This test does not screen for any
other chromosome linked conditions.
This test is also suitable for women with a twin pregnancy.
• Quadruple test (Blood test)
The blood test measures the levels of four hormones in your blood. We use this
information together with your age and weight to estimate the chance of your
baby having Down’s syndrome. If the chance is more than 1 in 150 we would say
that this is an increased chance. If the chance was less than 1 in 150 we would
say that this a low chance. The test can be performed between 14 weeks and 2
days and 20 weeks of pregnancy. We would aim to perform this test at about 16
weeks of pregnancy. This test is offered to women who book for care later in
pregnancy or for those where the sonographer has not been able to measure
the fluid at the back of the baby’s neck.
These blood tests does not tell you whether your baby definitely has Down’s
Syndrome. It simply tells you whether you are at increased chance or low chance
of having a baby with Down’s Syndrome. If you are at increased chance it does
not mean that your baby definitely has Down’s Syndrome – even in the increased
chance group the majority of babies are normal. If you are at low chance it does
not mean that your baby definitely does not have Down's Syndrome. There is a
small chance that your baby may still have Down's Syndrome.
9
What does 1 in 150
mean?
If 150 babies were born just
one of them would have
Down’s syndrome. The
other 149 would not have
Down’s Syndrome.
If your screening test showed that you were in the high risk group you would be
offered an amniocentesis or Chorion Villus Biopsy find out definitely (over 99%
accurate) whether your baby had Down’s Syndrome or not. Only you can decide
whether to have the amniocentesis test CVB. No one else can make that decision
for you. That is why you should think very carefully before you have the
screening test.
• Amniocentesis (explained more fully on pages 14-15)
An amniocentesis involves putting a needle into your tummy and taking some of
the fluid from around baby. This test would tell you definitely whether your baby
had Down’s Syndrome or not. Amniocentesis carries a small risk of miscarriage.
Some women who are already at higher risk, because they have had a previous
baby with Down’s Syndrome may feel that they need to have a definite answer
and are prepared to accept a small risk of miscarriage in order to find out. Such
women may choose not to have the screening test, first but proceed directly to
amniocentesis. If you feel this way please discuss it with your doctor or midwife.
• Chorion Villus Sampling (explained more fully on page 16)
Women at particularly high risk of having a baby with Down’s Syndrome may
choose to have chorion villus sampling. This test involves taking a small piece
of the placenta (afterbirth). Although the test can be done earlier in pregnancy
(from 11 weeks' gestation) than an amniocentesis, the risk of miscarriage
is higher.
In my last pregnancy the blood test was ok –
do I need to have it again?
Every pregnancy is different. Results from a previous pregnancy don’t apply to this
pregnancy. Also you are older now than you were last time so the risk of Down’s
Syndrome has increased.
10
Does the blood test check for anything else?
Although the tests are primarily tests for Down’s syndrome, a raised or low level
of some of the hormones can indicate the possibility of other problems in the
pregnancy. In the quadruple test we know that a high level of one of the hormones
(aFP) is seen in pregnancies where there may be a problem with the development of
the spine (spina bifida – see page 12), or the baby’s tummy wall. It can also be high if
there has been bleeding in the pregnancy. When we see a high level it alerts us to
check the growth of the baby later in the pregnancy. However, it can also be high in
some normal pregnancies. If the level of the chemicals were raised we would arrange
a detailed scan to check your baby’s spine and tummy wall.
If any of the hormone levels were high or low we would suggest repeating the scan
later in pregnancy to check the growth of the baby. This would be done in the
Placenta clinic.
Fetal Growth Restriction
Fetal growth restriction (FGR) occurs where the baby’s growth slows down in late
pregnancy and this means that the baby will be smaller than expected at birth. This
complication occurs in around 5-8% of pregnancies and can cause problems for the
baby during and after birth. It is therefore important that doctors and midwives
detect this problem as early as possible. The most common cause of FGR is a problem
with the placenta (afterbirth) which reduces the supply of nutrients necessary for
baby’s growth and development.
Research has shown that changes in some of the blood hormones measured in
the Down’s screening test can also alert doctors to the possibility of problems with
the placenta and FGR later in pregnancy. If these changes are present an extra
ultrasound scan at around 23 weeks of pregnancy will give doctors a better idea of
whether FGR is likely to occur and to plan your care appropriately. Therefore, if your
hormone levels indicate a possible risk, you will be invited to attend for a scan at 23
weeks of pregnancy at the Manchester Placenta Clinic. Saint Mary’s is one of the first
hospitals in the country to offer additional ultrasound scanning when these hormone
levels indicate a risk.
It is important to stress that these changes in hormone levels do not mean there is a
problem with the baby’s growth; only that the risk of growth restriction is increased.
Most women who have these hormone changes will have a normal pregnancy and a
normal sized baby.
How do I get the blood test done?
Discuss this with your midwife. She will arrange an appointment for the test
at the appropriate stage of your pregnancy.
How will I get the result?
Your midwife will ask you how you would want to be contacted if the test shows
that you are at increased risk of having a baby with Down’s Syndrome. The quickest
way is for us to phone you.
If the test shows that you are low risk we will write to you. The results take about
2 weeks.
Please think carefully! Remember that everyone’s circumstances and views are
different. Would the information from the test alter what you do in your pregnancy?
The test will be offered to you, but it is your own personal choice whether to have it
or not.
11
Spina bifida
Spina bifida is the name of a condition where there is an opening somewhere along
the length of the baby’s spine. In its worst form it causes paralysis of the lower limbs
and permanent incontinence of the bladder and bowels. It can also cause a build up
of fluid in the brain (hydrocephalus). Spina bifida occurs in one out of every
500 pregnancies.
Can I do anything to prevent my baby having spina bifida?
By taking the vitamin Folic acid you can reduce the chance of your baby having spina
bifida. Ideally you should take a 400 microgram tablet of folic acid every day for
three months before you get pregnant and for the first twelve weeks of your
pregnancy. You can buy the tablets from the chemist or supermarket or get a
prescription from your doctor.
You may be at greater risk if:
•
You have already had a pregnancy affected by spina bifida
•
You or your partner has spina bifida
•
You or your partner has a parent/brother/sister with spina bifida
•
You are taking tablets for epilepsy
•
You have Diabetes (Type 1 and 2)
If you fall into one of these groups, you will need to take a stronger 5
milligram tablet of folic acid which is only available by getting a prescription
from your doctor.
Are there any tests for spina bifida?
The best way of checking for spina bifida is the anomaly scan which offered between
18 weeks and 20 weeks plus 6 days of pregnancy.
The level of a chemical in the mother’s blood (aFP) (which is checked as part of
the Quadruple test for Down’s Syndrome) is raised in women whose baby has spina
bifida. However, it can also be raised for other reasons, for example, if a woman has
bled during pregnancy. If the level of aFP was raised the next step would be to
arrange a detailed scan to look at the spine, and the rest of
the baby.
Twins or triplets (multiple pregnancy)
Although most twins and triplets are normal, these pregnancies do require more
monitoring than usual.
If you have a twin pregnancy you will be offered the combined screening test
for Down’s syndrome. If you have a triplet pregnancy the combined screening is not
usually offered. You would be seen in a specific Multiple Pregnancy Clinic where your
doctor or Midwife will discuss your options with you.
In some multiple pregnancies there is an increased risk of abnormalities in the babies
and the scans can be more difficult to perform.
More scans will be offered during your pregnancy to check on the growth of the
babies and to check for complications.
Your midwife or doctor will be happy to talk to you about the implications and
possible problems of a multiple pregnancy.
12
Information about others tests that may be
relevant to some pregnant women
•
Immunity to Chickenpox
•
Glucose tolerance test to check how well your body deals with sugar
in pregnancy.
•
Amniocentesis
•
Chorionic Villus Biopsy (CVB)
Immunity to Chickenpox
Most adults are immune to chickenpox, either because they had it when they
were younger, or because they have been in contact with it so much that they
have built up their immunity. Chickenpox is therefore much less common in adults
than children.
However, if a pregnant woman gets chickenpox it can cause a severe pneumonia.
Effects on the unborn baby are rare.
If you happen to come into contact with someone with chickenpox during your
pregnancy you should let your midwife know immediately by telephoning Saint
Mary’s Hospital on 0161 276 6423. Please do not attend the antenatal clinic,
telephone the above number and ask to speak to a midwife.
A sample of your blood taking at your booking visit will be checked to see whether
you are immune to chickenpox or not. If you are already immune, then nothing
more needs to be done. However if you are not immune you may be offered some
treatment. The treatment may prevent you from developing chickenpox, or if you
still get chickenpox it would be milder.
Glucose Tolerance Test
Usually your body controls the levels of sugar in the blood. Sometimes in pregnancy
the control of the level of the sugar in the blood is not quite as good as it should be.
These women tend to get higher levels of sugar than normal and this is called
‘Gestational Diabetes’ (Gestational means related to pregnancy).
Certain groups of women (women from South Asia, Middle Eastern or Afro
Caribbean background) are more likely to develop gestational diabetes and women
with a family history of diabetes or who are obese. Your midwife or doctor will offer
you a Glucose Tolerance Test will see how your body handles
a measured amount of sugar.
13
What is involved in the test?
•
Have nothing to eat or drink (except water) from 10.30 pm the night before
the test.
•
Attend the Antenatal Clinic at the appointment time you have been given.
•
A blood sample will be taken to measure the level of sugar in your blood
when it is at its lowest (you’ve been starving all night).
•
You’ll then be given a measured amount of sugar in a drink (don’t eat or
drink anything else for the next two hours).
•
After two hours a second blood sample will be taken to see how your body
has dealt with the sugar you were given.
What will the results show?
•
If the test is normal nothing further needs to be done.
•
If the test shows high blood sugar levels you will be put in contact with the
Diabetes Specialist Midwives for advice.
What happens after I have had my baby?
•
As this problem is related to pregnancy your blood sugar usually goes back to
normal when the pregnancy is over.
•
Women who are diagnosed with gestational diabetes are offered a glucose
tolerance test six weeks after delivery of a baby. This is to confirm that your
blood sugar has returned to normal.
•
It is important to adhere to healthy lifestyle changes, for example diet, and
maintain a normal weight and exercise as you are at increased risk of
developing diabetes in later years.
•
You are advised to see your GP yearly to have a blood test to detect early
onset of diabetes.
•
If you get pregnant again it is likely that you will develop gestational
diabetes in a future pregnancy.
Amniocentesis
When the baby is in the womb it is surrounded by amniotic fluid. This fluid contains
cells that have the same chromosomes as your baby. This means that we can use a
small amount of this fluid if we want to check the chromosomes of the baby.
How is the amniocentesis done?
An amniocentesis is done by passing a fine needle through the mother’s abdominal
wall into the fluid around your baby. We watch the needle carefully on ultrasound
scan all the time to ensure that it is correctly positioned in the fluid. We then take
15-20 mls (three to four teaspoonfuls) of fluid and send it to the laboratory. The
procedure only lasts for a few minutes. Very occasionally we do not get enough fluid
at the first attempt and the needle needs to be inserted again.
14
Does it hurt?
You feel a prick as the needle goes through the skin. This is similar to the prick you
feel when having a blood test. Once the needle is inside there is some vague
discomfort, but not pain, and it only lasts for a minute or two.
What should I do after an amniocentesis?
For the first day or two you may have some crampy pain, like mild period pain. You
may find it helpful to take paracetamol – it is safe to take Paracetamol has been
used routinely during all stages of pregnancy for pain relief. Overall it does not
seem to have any harmful effects on the baby. We advise you to take things easy for
the first day or two, take a couple of days off work and avoid doing the housework.
If you have a lot of pain, any bleeding or if you lose any fluid you should contact
your local hospital.
Although we use sterile equipment and antiseptics during the test there is always a
small risk of introducing infection. If you develop flu like symptoms or get a smelly
vaginal discharge within three weeks of the test you should see your family doctor
(GP), or the doctor at your local hospital.
When will I get the results?
The three most common chromosome problems, including Down’s syndrome, will be
checked for in 2-3 working days. We will contact you when this first part of the test
is available. The lab then continues to check the other chromosomes and it takes
approximately two weeks to get the final result on all the chromosomes. We will
discuss with you how you would like to be informed of the result. Many women like
to be telephoned with the result as this is the quickest way of getting the results.
Will the procedure need to be repeated?
If we only get a very small sample, or if the sample is blood stained the result will
take longer. Occasionally the cells from the sample fail to grow in the laboratory.
This is rare, but if it does happen the test would have to be repeated.
How accurate is the test?
The test is very accurate – over 99%. However, it is not 100% accurate.
What are the risks associated with the test?
There is a small risk of miscarriage associated with the test. The risk of miscarriage
for any pregnant woman at this stage of pregnancy is about 0.5%. By doing an
amniocentesis test we increase the risk of miscarriage by a further 0.5%, giving an
overall risk of miscarriage after the test of 1%. Unfortunately, if a woman miscarries
there is no way of knowing whether this was due to the test or whether it would
have happened anyway, even if she hadn’t had the test.
Studies have suggested that if an amniocentesis is carried out before 14 weeks of
pregnancy there is an increased risk of miscarriage. To avoid this risk we do not
perform the amniocentesis test before 15 weeks of pregnancy.
15
Chorion Villus Sampling (CVS)
Both the baby and the placenta (afterbirth) develop from the same cell and so the
chromosomes present in the cells of the placenta are the same as those of the baby.
This means that we can use a small piece of tissue from the placenta (a chorion villus
sample) if we want to check the chromosomes of the baby.
How is the CVS done?
There are two ways in which samples can be obtained:
1 Usually the CVS is done by passing a fine needle through the mother’s abdominal
wall into the placenta. We watch the needle carefully on ultrasound scan all the
time to ensure that it is correctly positioned in the placenta. The needle is then
moved backwards and forwards to break off a tiny piece of placental tissue. The
procedure only lasts for a few minutes. Sometimes we do not get an adequate
sample at the first attempt and the needle needs to be inserted again.
2 Occasionally the CVS is done by passing a fine flexible tube through the cervix
(neck of the womb) into the placenta. Exactly the same sample is obtained. For
some women this method is more appropriate than the first.
Does it hurt?
You will feel some discomfort. However the test only lasts a few minutes and most
women cope quite easily.
What should I do after a CVS?
For the first day or two you may have some crampy pain, like mild period pain. You
may find it helpful to take paracetamol. Paracetamol has been used routinely during
all stages of pregnancy for pain relief. Overall it does not seem to have any harmful
effects on the baby. If the test has been done through the cervix you will probably
have a little vaginal bleeding. We advise you to take things easy for the first day or
two, take a couple of days off work and avoid doing the housework. If you have a
lot of pain or bleeding you should contact your local hospital.
When will I get the results?
Most of the chromosome tests take approximately 2 weeks and rapid testing takes 2
– 3 working days. We will discuss with you how you would like to be informed of the
result. Many women like to be telephoned with the result as this is the quickest way
of getting the results.
How accurate is the test?
The test is very accurate – over 99%. However, the test is not 100% accurate.
Will the test need to be repeated?
Occasionally we get an inconclusive result, or the cells from the sample fail to
grow in the laboratory. This is rare, but if it does happen the test would have to be
repeated.
What are the risks associated with the test?
There is a small risk of miscarriage associated with the test. The risk of miscarriage
for any pregnant woman at this stage of pregnancy (12 weeks) is about 2%. By
doing a CVB test we increase this risk by a further 1%. Unfortunately, if a woman
miscarries there is no way of knowing whether this was due to the test or whether it
would have happened anyway. Some studies have suggested that if a CVS test is
carried out before 10 weeks of pregnancy there is a small risk of abnormalities to the
baby’s hands and feet. To avoid this risk we do not perform the test before 11 weeks
of pregnancy.
16
Comparing amniocentesis and Chorionic Villus
Sampling (CVS)
Test
Amniocentesis
Chorionic Villus
Sampling
When
Miscarriage risk
Result
1%
Rapid test 2-3 days
Approximately
2 weeks
2-3%
Rapid test 2-3 days
Approximately
2 weeks
15 weeks onwards
11 weeks onwards
Amniocentesis
Chorion Villus Biopsy
Fluid is taken from around the baby
A small biopsy (sample) of the
placental tissue is taken
Ultrasound
transducer
placenta
17
A quick guide to testing in pregnancy
Test
Dating
scan
Combined
screening
Quadruple
test
Type
Looks for When Results
Checks dates,
baby’s
heartbeat,
Screening
8-14
identifies twins
and
weeks
and
diagnostic
some serious
abnormalities
Screening
Screening
Down’s
syndrome
Immediate
5 days (letter
11-14
within 2 weeks
weeks
of test)
Down’s
syndrome
15-20
weeks
Spina bifida
15-20
weeks
5 days
How is the
Advantages Disadvantages
test done
Ultrasound
scan
Takes 10
minutes
Safe and
usually
reassuring
Abnormal scan
may lead to
further testing
Early in
pregnancy,
High risk result
Nuchal
Translucency quick, suitable
will need
(NT) scan and for twins. No
diagnostic for
blood test
miscarriage
definite answer
risk
Blood test
Quick No
miscarriage
risk
Not suitable for
twins. High risk
result will need
diagnostic test for
definite answer
Blood test
Quick No
miscarriage
risk
Not specific. High
risk results will
need follow up
with detailed scan
AFP
Quadruple
test only
Screening
Chorionic
villus
sampling
A fine needle is
guided by scan
through the
Definite
mother’s
answer Nearly
Same as
11
Miscarriage risk
Approximately abdominal wall
Diagnostic
100% accurate
to take some
amniocentesis weeks
of 2-3%
2 weeks
of the tissue Results early in
pregnancy
from the
afterbirth
(placenta)
5 days
A fine needle is
Chromosome
guided by scan
Definite
abnormalities
through the
15
answer nearly
such
mother’s
Miscarriage risk
weeks Approximately
as Down’s
Amniocentesis Diagnostic
abdominal wall 100% accurate
of 1%
and
2 weeks
to take some Results early in
syndrome and
over
of the fluid
pregnancy
other genetic
from around
conditions
the baby
Only picks up
approx
70% of
Abnormalities
Screening
Ultrasound
18-21
Anomaly
abnormalities.
in the way
Immediate
and
Safe
scan Takes 20
weeks
scan
Abnormal scan
baby has
minutes
diagnostic
may lead to
developed
further testing
18
What if something is wrong with
your pregnancy?
Although most babies being tested will be found to be normal, there will be some
pregnancies where the baby is found to have a serious problem.
Parents will have several options. Some will decide to proceed with the pregnancy
and prepare for the birth of their baby. Others will make the difficult decision that
the best option for them and their family is to terminate the pregnancy.
Should you and your partner make this difficult decision to end the pregnancy, the
way the procedure is carried out will depend on how far through the pregnancy you
are. Your obstetrician will be able to give you more details about this and will
support you throughout this difficult time, whatever your decision may be. It is more
important to think about how you would feel if a problem is detected before having
any of the tests. If you would like more information before you decide whether to
proceed with the testing, please ask your midwife or doctor.
Supervisors of Midwives
All midwives are supported by a Supervisor of Midwives whose aim is to ensure the
safety and wellbeing of you and and your baby. If you have any issues regarding
your pregnancy or maternity care you can contact a supervisor of midwives at any
time, day or night at: Tel: 0161 276 1234 (ask for bleep number 6060).
Useful contact numbers
Antenatal clinic
0161 276 6423
Delivery suite
0161 276 6556
Midwifery Day Unit
0161 276 6404
Further information on scans
www.preg.info/scan
Miscarriage Association
01924 200 799
TAMBA
0800 138 0509
Down’s Syndrome Association
08452 300 372
Cleft Lip and Palate Association
0207 833 4883
Sickle Cell/Thalassaemia advice
0161 274 3322
Antenatal Results and Choices (ARC)
0207 631 0285
19
No Smoking Policy
The NHS has a responsibility for the nation’s health.
Protect yourself, patients, visitors and staff by adhering to our no smoking
policy. Smoking is not permitted within any of our hospital buildings or
grounds.
The Manchester Stop Smoking Service can be contacted on
Tel: (0161) 205 5998 (www.stopsmokingmanchester.co.uk).
Translation and Interpretation Service
Do you have difficulty speaking or understanding English?
☎ 0161 276 6202/6342
Maternity Service
Saint Mary's Hospital
Oxford Road
Manchester
M13 9WL
www.cmft.nhs.uk
TIG 62/03 Produced November 2011 Review Date November 2013 (SF Taylor CM3281)