CVS and Amniocentesis tests

[Orb]

Helly everyone, I'm unsure what are the similarities and differences between CVS and amniocentesis tests. I think that they are taken at slightly different points in early pregnancy using a similar method? Do they test for the same things and is one test more accurate than the other test? Has anybody had either/both of these tests? I'd be interested in hearing any good, bad or ugly stories, thanks.

One is done earlier than the other and has quicker results. Neither can test for the majority of disabilities like cerebral palsy (more common than Down's syndrome) and to be honest and very very blunt as a mother of two SN children (one with CP, one with ASD, neither of which can be tested for) and a disabled person myself, both are to 'cull' disabled babies.
I've never had any testing done in any of my 4 pregnancies because I accept how my child is.
Just my opinion.

both are to 'cull' disabled babies

Well, that view assumes that the parents will abort when told the foetus has a problem. Some parents would not abort and would instead use the information as a means of preparing for the arrival.

there is that. But I'd be scared of the m/c risk with both tests. Dont know if they carry any other problems.

CVS is done earlier in pregnancy (from about 12 weeks), it samples the villi of the placenta. Amniocentesis is done after 14-16 weeks and takes a sample of the amniotic fluid.

In the early days it was thought that CVS had a slightly higher miscarriage rate than amnio - partly because it is done earlier in pregnancy when more pregnancies are lost naturally. There isn't much difference between the loss rates now, I believe the often quoted rate is 1% but that is hugely variable - if you go somewhere where they do loads (Kings/FMC etc) the loss rate is a fraction of a %. If CVS is done too late it can lead to malformations of the digits, this is a recognised issue and CVS isn't offered late enough for this to be a problem anymore.

Generally results from a CVS come back faster than from an amnio (they can test the cells directly rather than having to culture them) - the quickest results are from FISH which you can get back in 1-2 days but is only preliminary - i.e. they test only the most commonly affected chromosomes sex chromosome & 21, 13 & 18. It takes a few days longer to get the full report.

Both test for abnormalities of chromosome numbers (aneuploidies) and if you have existing problems with translocations etc they can test for those specifically but that wouldn't be done routinely. Amniocentesis can also test levels of AFP which is elevated in open neural tube defects.

I had a CVS when scans suggested my baby was at greatly increased (1 in 16) risk of Trisomy 18 (Edward's Syndrome). Luckily the results were normal and the pregnancy continued pretty normally.

I had CVS done when I was pregnant with DD2. I had the test as she was given a 30% chance of having Trisomy 18.

The negative results of the CVS allowed me to spend the rest of my pregnancy worrying only about the condition my daughter was born with (she was given a 50/50 chance of surviving that). It kept me sane and also helped us to prepare our five year old for DD2's arrival.

DD2 is now looking forward to her third Christmas.

Orb, I wish you all the best if you are having to make difficult decisions at the moment.

Patsy x

Hi Orb

I think by posting this question on the SN board will give you different responses than posting in the general Pregnancy section. I was offered amnio at 19 week preg. for a 1 in 90 chance of a baby with Downs Syndrome. I decided that as I wouldn't terminate at that late stage in pregnancy I wouldn't go ahead (even though the hosp offered next day results as they'd cocked up the statistics initially on the triple test)
DD3 was born with DS. I don't feel that knowing in pregnancy would have been much help, it would have probably been a very fearful time. The reality of life with a child with DS is not only manageable, but life enhancing. I have done things and met people who I would not have met had DD3 been NT. And of course there's DD3 herself who is who she is. I can't imagine her, and wouldn't want her to be any different.

All the best with your fact finding x