It's a month or so old but I just noticed this news story http://news.bbc.co.uk/1/hi/health/4634593.stm
There are some inaccuracies in the report but the general gist is right - basically if a woman has an amniocentesis or a chorionic villus sampling (both of which put the baby at risk of miscarriage) because she has had a high risk from blood tests and/or nuchal ultrasound, the national guidelines may be reviewed so that they will only have a quick cheap test for Down's, Patau and Edward's syndromes.
At the moment (in most of the London area but not nationwide-yet) the NHS will pay for both the quick test (to see if baby has Down syndrome or not) and the long term culture test (full karyotype) which looks at all the other chromosomes in detail to pick up other abnormalities. These are much rarer than DS but they do happen.
(Some parts of the country still only offer the full test on the NHS and patients can pay privately if they want a 'rapid' result too).
My personal thoughts are that if I chose to put a pg at risk of miscarriage by providing a sample, I would like as much information as possible about the baby's chromosomes.
Just thought I'd better mention, if severe abnormalities are seen on scan the full test would be offered....but the quote in the news report about most of the potential 'missed' chromsome abnormalities will be picked up by abnormalities seen on ultrasound scan is 'dodgy' IMHO, and also that scan occurs at 20+ weeks, so if a woman has already had a CVS due to a nuchal test at say 12 weeks, and had a normal result from the rapid test, she would have to have another invasive test ie. amnio, if abnormalities were picked up at her 20 week scan.
(Bit of a rant I know, but this is something I care about!)
I agree that that the later an investigation is carried out, the riskier it is. And I agree that if a woman is going to risk miscarrying from an investigation the information that can potentially be gained has to be substantial.