Diagnostic tests - amnio and CVS
Amniocentesis and CVS are two diagnostic tests that will usually be offered to women during the third and fourth months of pregnancy if there is some concern there may be something wrong with the baby. This may be because a Down’s syndrome screening test has suggested the baby is at higher risk, or because ultrasound screening has detected signs that may indicate a chromosome abnormality.
Both tests are used to look for chromosomal conditions such as Down's, Patau's and Edwards' syndromes. Amnios and CVS provide a definite diagnosis, which screening alone cannot, though parents may have to wait days and sometimes weeks to get back every result from the test. Both procedures carry a small risk of causing a miscarriage. The overall risk of you having a miscarriage after CVS is about 1 to 2%. In other words, about one or two in every 100 women who have CVS will miscarry. For amniocentesis, the rate is about one in 100. These figures vary slightly from hospital to hospital.” (Screening Tests for You and Your Baby - Public Health England July 2017)
The CVS test, which is usually done from about 10-13 weeks, involves taking a tiny sample of tissue from the placenta. Amnios, usually done around 15-18 weeks, involve taking a small sample of amniotic fluid, the protective fluid round the baby. (For more detailed information see 'Resources' and also 'Antenatal Screening' for more personal experiences of amnios and CVS as well as information about AFP and blood tests.)
Women expressed a range of views about these tests; some felt that they needed to know more about what was wrong with the baby, others were more cautious about the tests and found it hard to make an informed decision about the tests in the time available.
- Age at interview:
- Pregnancy ended in 2002. No. of children at time of interview' 2 + . Ages of children' 7, 4. Occupations' Mother - mother, Father - management consultant. Marital status' married. Ethnic background' White British.
I was a bit worried about it, because they're sort of putting a large needle into your stomach, which you know was a bit alarming. But I think, to be quite honest, by that stage I was in such a shock, and anything could have happened, you know it felt like anything was possible on that day. Then I don't know, I think when you've been given such bad news that you're not expecting to hear all sense of judging things, a normal way of judging things, goes out the window, in that particular time and on that particular day.
And it felt like the goal posts had moved. I mean I hadn't wanted to have an amnio in the course of a normal pregnancy, and that's why I'd gone for the nuchal scan to sort of try and get more information. We'd done that, we'd got more information - and there were problems - so the goal posts had moved really. It wasn't a normal pregnancy any more.
And I am the sort of person I think - I'm sure lots have said this but I don't know if everybody is exactly the same - I'm the sort of person who needs to know, I'd rather know. So there was no way I wasn't having that CVS. And it did feel a bit like, 'oh gosh' you know, but she seemed very experienced, the consultant that did it, and I felt very confident in her that she knew what she was doing, and I sort of thought, 'Well, I'm prepared to take the risk. I'm prepared to take the risk. If it will cause a miscarriage, we need to know what's going on here, and this is the only way we're going to find out for sure'.
Most women willingly followed the advice of health professionals about which test was most appropriate for their baby's problems. Many women felt the tests were well worth having and said that they were reassured by seeing the baby on the scan as they had the test, and how health professionals tried to put them at ease during the procedure itself.
- Age at interview:
- Pregnancy ended in 1999. No of children at interview' 2 + . Ages of other children' 4, 1. Occupations' Mother - Engineering procurement buyer. Father - Project manager. Marital status' married. Ethnic background' White British [Scottish].
What was the amnio like, can you describe that for me?
It was absolutely fine. It didn't hurt at all. It was just they put some gel on you - well they scan you first of all to see where the baby is and because they don't want to touch the baby obviously, with the needle - and they're looking for a bit of the amniotic fluid that they can get into without touching the baby.
So they just scan you and put some gel on your tummy, like antiseptic sort of, antiseptic, what's the word I'm looking for? Anaesthetic gel, and put a needle in. It wasn't sore at all, I mean, I thought, it was like 'Oh, this horse needle going in', but it really wasn't sore at all, not for me anyway.
And you, and they tell you about all these different rates that people have for amnios because it is, I think, up to, for up to a month afterwards you have to sort of be careful, and you might lose the pregnancy through that. So that's another, that's another thing you have to think about, that was another consideration.
We were going for an amnio and the threat of a miscarriage after that is very real as well but I think what swung it for us was that we were dealing with a life-threatening condition. I mean, if it had been something like Down's of spina bifida or these other ones that are along a spectrum, I don't know what we would have done. But it was the fact that we were dealing with something that the baby was going die, we took the risk of having the amnio but it wasn't sore, wasn't sore at all.
Sometimes one test was more appropriate for the baby than another - for example a woman who was expecting non-identical twins had a CVS so that samples were taken from the placentas of both her babies to test which of them had Down's syndrome.
- Age at interview:
- Pregnancy ended in 1995. No. of children at time of interview. 3 + . Ages of other children' 12, 12 and 9. Occupations' Mother - nurse, Father - insurance broker. Marital status' married. Ethnic background' White British.
But the whole gamut of ideas' anyway the next day I, we went up to the [city] teaching hospital and we saw the consultant there, who was absolutely out of this world, he was absolutely superb. And he said that he also did find that, he wondered if both babies had Down's syndrome or probably something similar and what he suggested we did was have a CVS taken from both placentas.
Because I was expecting twins obviously they were, they were non-identical, and we didn't know they were a boy and a girl at that time, but I think he could probably tell. And so he took a CVS, a sample of the placenta from each baby. And he, they couldn't actually manage to do the CVS, so they had to do it again. So it was really uncomfortable and it was, as well as being totally bogged down mind-wise, it was actually very uncomfortable as well. And he then said basically, 'What you now do is wait. You wait for probably up to two weeks. We'll get the results back to you as soon as we possibly can'. As I say he was absolutely lovely.
And the next two weeks were, oh, absolutely horrendous. It's difficult thinking about it even now really. We just, you know, well, I basically, I think I sat on the sofa for two weeks, because after having had the CVS they said, 'There's a slightly increased risk of miscarriage'. So I was very scared about that. And I just waited. And I was on my own at home when the phone rang, and it was, I think it was a midwife or one of the counsellors that, at the hospital. And she said, 'Are you on your own?' And I said, 'Yes, I am'. I said, 'But I just need to know'. I didn't want to wait for anyone else to get there. And she said, 'It's a boy and a girl'.
And the midwife said, 'You're expecting a boy and a girl, and the boy has got Down's syndrome, the little girl's fine'. So on one hand it was the most immense relief that our little girl was fine, but we were devastated. And I think I phoned my husband at work, and I think he was very like me, he just wanted to know. And I felt very mean telling him over the phone, but I had no choice because again he wanted to know.
Many women felt reassured about having the test because they knew (or found out) that the test would be done by an experienced consultant or in a teaching hospital where they felt that clinicians would have had plenty of practice.
- Age at interview:
- Pregnancies ended in 1996 and 1999. No. of children at time of interview' 2. Ages of children' 8, 2. Occupations' Mother - mother, formerly civil servant, Father - economist. Marital status' married. Ethnic background' White British.
And I have every test under the sun. I had, I've had the three amnios, and I would always have an amnio again because once you've had them, all the things you read in books about how they're great big needles and about how potentially dangerous they are, I didn't worry about that in our local hospital, which is a very good teaching hospital, a very big hospital because I know how skilled they are, how many they do a year, they do a great number. And I think a lot of the statistics are based on smaller hospitals where the staff have less experience, and that's where the possible problems can occur. But I'm not particularly prone to miscarriage because even with these babies that were in a real state I never miscarried, I never even bled with any of them. So I've always gone for amnio.
A few women said they had found it difficult to make a decision about the tests because of concerns about the risk of miscarriage - several women had been told that an amnio carried a slightly lower risk than the CVS. (Research indicates that on average about 1% of women who undergo amnio or CVS miscarry and that there is now very little difference in terms of risk between CVS and amnio - see Screening Tests for You and Your Baby - Public Health England July 2017).
Although most women didn't like the idea of having a test that many described as 'invasive', most women took the view that and it was worth having 'a few minutes of discomfort' to find out what was wrong with the baby. However, several women were surprised that the test was more painful than they had been led to expect.
- Age at interview:
- Pregnancy ended in 1998. No of children 2 + . Ages of children at interview' 7, 4. Occupations' Mother - classroom assistant, Father - Pottery worker. Marital status' married. Ethnic background' White British.
I was nervous about having the amniocentesis, and I was also nervous because I read and I was told by the consultant, that there is a slight risk of miscarriage following the amniocentesis test. And one of my worries that I would have the amniocentesis test the baby would be fine but I would miscarry, and I felt that if that had happened I would blame myself because nothing was wrong and that I'd have gone for my peace of mind and I had caused this to happen.
The amniocentesis test is so I still wanted it even though that risk had been explained to me. I felt that that slight chance was a risk that I needed to take.
The test itself, it was uncomfortable and it was slightly painful, it's not the worst pain I've ever had. But, it was explained to me all the way through by the consultant, what he would do, and he encouraged me to, and my husband, to look at the screen. And he said, he was doing that to make sure that we knew that he was performing the test safely and that the baby wasn't being harmed by the needle. And he encouraged us to look at it.
Once he'd done the test, he just told us that it would be sent away, and the results would come back, and he left the room. There was no other explanation. We were basically left to get ourselves together and go home.
- Age at interview:
- Pregnancy ended in 2002. No of children 3 + . Ages of other children at interview' 7, 3 and 9 months. Occupation' Mother - mother, formerly TEFL teacher, Father' IT consultant. Marital status' married. Ethnic background' White British.
Well I had the amnio at the first appointment at the big hospital. And it was one of those things where they say, 'This is a slight discomfort' was how they described it [smiles]. I wouldn't describe it like that.
And they pushed the results through quickly so that they'd have them ready.
How would you describe the amnio, in your own words, could you tell me about that?
Well the amniocentesis its like having a red hot poker put into your stomach it is unbelievable, unbelievable, because the other thing you have to do is stay still, you have to stay completely still, and they obviously watch on a scanning machine while they're, to make sure they get it, the needle in to the right place.
And as I say they describe it as 'mild discomfort' it's rather more than 'mild discomfort' in my books.
I don't think the amniocentesis took more than a few minutes. But the, because of the lack of amniotic fluid he had already said, he might 'I might have to do this again, if I don't get a pocket straight away I'll have to go in again,' and I was, and this was while he was doing it, because it hurt so much, I was just praying that he was going to get some. And he did.
Waiting for results from amnios and CVS
Waiting for the test results was always an anxious time for parents, and several women talked about finding it difficult to carry on 'as normal' for the sake of their other children. It usually takes 2-3 weeks to get the full results from amnios and CVS tests. However, most centres offer quick results within 3 working days, using the QF-PCR test (which provide a rapid diagnosis of the most common chromosome abnormalities including Down's syndrome, Edwards' and Patau's syndrome). Sometimes parents didn't understand that the baby was being tested for more than Down's syndrome, and so were extremely upset when later test results from the amnio showed the baby had a different chromosome anomaly such as Edwards' syndrome.
- Age at interview:
- Pregnancy ended in 2003. No of children at interview' 2 + . Ages of other children at interview' 4, 2 months. Occupations' Mother - formerly local government officer, Father - retired from army. Marital status' married. Ethnic background' White British
I think, to start with they came back with, there's one result comes back quite quickly from the amnio, so I think three or four days later the result came back for Down's Syndrome, and it was clear, everything was okay.
I think that came on a Friday afternoon again, ironically, and we sort of spent the weekend with a think false hope, because we just thought, 'Well if that's okay.' that was the main one, because no one had really told us about the other things they were checking for. And it was always the focus was always on Down's Syndrome, and spina bifida.
So I think it kind of gave us hope that well probably things are okay - if that main one is okay, things might be okay. Then, I think it was a couple of weeks later it took about two weeks for the full results to come back. And we were just waiting for this phone call from the hospital. And normally it would be a midwife in the scanning department who would just phone and say, 'Things are okay'. And it was the consultant herself who made the phone call.
And I remember it was lunchtime here when I answered the phone, and she said who it was, and I knew immediately that there was a problem with the baby, because I just thought that she didn't make routine phone calls to tell you that things were okay.
And I immediately said to her, 'Oh but the Down's syndrome result came back and it's clear'. And she said, 'Yes, but it's picked up another genetic abnormality with the baby'. And she asked for my husband and I to go into hospital as soon as we could. So we knew because of the sort of, immediate thing she wanted to see us, that something was, was badly wrong.
We made arrangements for our other little boy, and we went straight in that afternoon so within a couple of hours we knew, that the baby had Edwards' syndrome. And we were told that it was 'incompatible with life', that was the phrase that was used by the doctors.
Most women appreciated being visited personally by the midwife and having the news broken to them in person, though several said that they realised the minute they opened the door and saw the midwife that the results confirmed the baby's problems.
Some women asked if they could be told the test result as soon as possible which meant they had received the news over the phone. Several were on their own at home when they were contacted and told the test result but had had no one to turn to for comfort. One woman described hearing the news of her baby's Down's syndrome over the phone was 'a little bit like being hit over the head with a very large and heavy brick' and said how she had turned to her young son for comfort. Another woman had been given the news on the phone and found she couldn't cope with her young child and felt she needed to ask a neighbour for help.
- Age at interview:
- Pregnancy ended in 1999. No. of children at time of interview' 2 + . Ages of other children' 11, 2. Occupations' Mother - nurse, Father - policeman. Marital status' married. Ethnic background' White British.
What was extremely difficult was that I started crying and [daughter] started crying because she didn't know what was wrong, and I couldn't tell her and [my husband] was at work, he's an hour and a half away in [city]. And I just didn't know what to do really so I phoned my friend across the road, she wasn't in, so her husband couldn't understand me, and he thought maybe I was having a miscarriage, but I mean he's quite sensible, he's a policeman you know quite level-headed. And he came over and took [my daughter] and took her down to my friend's and my friend came up. So he cooked tea for the children that night.
I think what I mean they, they asked me 'How can we improve what we're doing?' and I said, 'The worst bit was picking up the phone,' I said, 'It would have been.' And then when I saw my GP, although she told me actually that 'Your doctor already knows and he's really upset.' And I thought he's only up the road, why didn't he come? I'd have much rather he'd knocked at the door really, but thinking about it there is no easy way, what do you do?
Well it can be done in lots of different ways.
Yes. I don't know whether it would have been easier if he'd phoned up and said 'Would you come up to the surgery?' or, I'd have still been stuck at that particular time.
Several women said they would have preferred to have had the news of the test results given to them in person, but realised that it was not always possible. Midwives can give the results of the test to people at home, at the antenatal clinic, over the phone or in a letter, this should be discussed with the woman beforehand.
Non Invasive Prenatal Test (NIPT) is another screening test that can be used to detect Down's syndrome. It is a non-invasive test using a maternal blood sample to test free-cell fetal DNA. During pregnancy, fragments of DNA from the placenta called free-cell fetal DNA circulate in the mother’s blood steam. These DNA fragments (CFFDNA) can be genetically tested along with the mother’s blood to show if there is an increase in the number of abnormal chromosomes. This screening test is not currently offered by the NHS, however some NHS Trusts have piloted the test and a number of maternity units do offer testing privately. The sample has to be sent outside the UK for analysis so the results take about two weeks to come back. The cost of the test varies between clinics (£350 to £550). Large scale studies show that the test has a detection rate of over 99% (ARC July 2017) and also tests for some other common chromosomal anomalies; Edwards syndrome (trisomy 18), Patau syndrome (trisomy 13) and Turner syndrome. It can be performed from 10 weeks of pregnancy and unlike amniocentesis and CVS has no risk of miscarriage. However if the NIPT gives a positive result, an amniocentesis is required for confirmation. For more information see our pregnancy resources. None of the people we interviewed had had this test.
Last reviewed July 2017.
Last updated July 2017.