Pregnancy screening tests

Antenatal appointments | Tests and scans | Miscarriage

Antenatal tests

The scans and tests available to pregnant women are a mixed blessing. Yes, they're an amazing insight into your unborn baby's health and wellbeing, but they can also ratchet up your stress levels to unpleasant heights.

If any of the non-invasive antenatal scans or blood tests indicate a higher than expected risk of your baby having or developing certain conditions, you may be offered diagnostic screening tests. These are known as invasive tests as they involve taking tissue or fluid samples from your body.

Chorionic villus sampling

Your age, any family history of inherited disorders or previous pregnancies where your baby had problems will influence whether or not your doctor or midwife recommends you have CVS. The decision - like all pregnancy screening - is up to you.

How is CVS done?

CVS takes place at about 10 to 13 weeks and involves inserting a thin needle through the abdomen into the womb or passing a small tube into the vagina and cervix to get cells  - chorionic tissue - for testing from the developing placenta. These cells have exactly the same genetic code as the baby and so any problem that shows up in these will also affect the baby.

The person doing the CVS will use ultrasound to guide the needle safely into the womb. The whole procedure takes about ten minutes.

"I had a CVS, it was uncomfortable rather than painful, and alarming to see the needle on the ultrasound, being jiggled about. I had some bruising and a bit of a sore feeling for a week or so. Bear in mind that you won't 'need' a CVS, it's your baby and your decision." geekgrrl

The results are usually available within two weeks, although some hospitals now offer faster results.

What is CVS for?

CVS can detect chromosomal disorders, for example Down's syndrome, inherited disorders such as cystic fibrosis, muscular dystrophy, thalassaemia and sickle cell anaemia, metabolic disorders such as phenylketonuria, and other conditions, such as Fragile X syndrome.

It doesn't test for physical problems such as spina bifida.

What are the risks from CVS?

CVS isn't risk-free: the NHS says that in between 0.5% and 2% of cases the procedure results in miscarriage. For some people, the risk of miscarriage is enough to put them off taking the test. It is never an easy decision.

"My sister-in-law had CVS and miscarried a few days later," says one Mumsnetter. "She bitterly regrets it, especially as the results came back clear."

But others feel the need to know is important for them and their family.

"I think it's the process that makes you nervous," says one mum, "but it only lasts ten minutes at the most. It is well worth the slight discomfort just to know your babies are OK."

Whatever you decide, it's a difficult step to take. If you decide to go for CVS, try to take someone with you, both for moral support and to make sure you get home OK.

"We were given a one in 13 chance of Down's syndrome, and a risk of a heart defect. We had to wait a week for the CVS test as I was bleeding internally and another week for results. It was the longest two weeks of my life. Our CVS results came back clear. Our daughter is perfectly healthy." Porridgebrain

Amniocentesis

An amnio indicates the likelihood of your baby developing certain chromosomal conditions, such as Down's syndrome, Edward's syndrome and Patau's syndrome - all conditions where a baby has an extra chromosome. It's the most commonly offered diagnostic test, according to the NHS.

How is an amnio done?

Amniocentesis is usually done between 15 and 19 weeks and involves inserting a needle into the womb through your abdomen to take a sample of amniotic fluid.

"The amnio itself wasn't too bad - the needle didn't hurt, and withdrawing the fluid was a weird and slightly uncomfortable pulling sensation, but tbh the most painful thing was dp squeezing my hand too hard." whinegums

"I watched the screen whilst doc was doing it and my DS (I was 16 weeks pregnant) moved as far away from the needle as possible and then really curled into the foetal position. It was a bit surreal to be honest." shabster

The results take two to three weeks, although tests for a specific chromosome are much quicker (you may have to pay for these). If the waiting is torture, get on Mumsnet and talk to other women who've been through the same thing.

You can find out the sex of your baby after an amnio, which is a bonus for some, but make sure you tell medical staff if you don't want to know.

What are the risks from an amnio?

Like CVS, there is a small risk of miscarriage - for every 100 women tested, one or two will miscarry. If you were to miscarry due to the test, this would happen within the next five days.

Your age, medical history, family history and the results of any antenatal scans and blood tests will determine whether or not you're recommended to have an amnio. Again, like CVS, that decision is up to you. And a very difficult decision it is too, for many women.

"I wanted a diagnostic test that would tell me 'yes' or 'no'. I understood all the risks and I honestly don't know what I would have done if the results had not been normal. I did what was right for me and my husband, and you must do what is right for you." Christie

"I was a nervous wreck," admits one mum. "I viewed myself as a racehorse with three big hurdles to get over: the test itself, the risk of miscarriage, and then getting the result."

It's not a 100% failsafe test - an amnio can't test for every condition, or disease, and can't guarantee your baby will be born completely healthy. It's possible to have a 'normal' result and then for your baby to be born with a chromosomal condition.

All of which makes it an agonising decision. Obviously, it's important to think beforehand about what you'll do if the results aren't good. If you wouldn't terminate a pregnancy, is there any point in risking miscarriage, however small that risk is?

"I know a lot of people say they would not terminate a the pregnancy if they were having a baby with an abnormality so there is no point having an amnio, but it is also useful, if the baby does have an abnormality, to prepare for the birth and arrange any necessary care the baby might need immediately after birth." WestCountryLass

Research to develop a non-invasive, prenatal blood test that will detect chromosomal disorders is ongoing. So, in future, anxiety about possible miscarriage may be removed from antenatal screening, but the dilemma about the results won't.

After the tests

"Do make sure you have 3-4 days of resting afterwards. You'll probably get a bit of cramping so just try to relax." Sassafrass

Call your midwife if any of these symptoms occur:

• Bleeding that's more than 'spotting'
• Fluid loss
• Feeling shivery
• Feeling as if you're having contractions

Antenatal screening can be a testing time in more ways than one: share your worries with other Mumsnetters, and your family.

"Let everyone know that actually, you are important and, yes, life does go on, but right now the priority is for a happy, healthy mummy and baby. I have been lucky with quite a sympathetic husband, and my mum has been great, but I have still had to remind them every now and again, that hang on, I'm struggling here and I need some help." HappyNewMum2Be 

Antenatal appointments | Tests and scans | Miscarriage