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The integrated test will detect 8 to 9 out of ten pregnancies with Down’s Syndrome (The triple tests detects 6 out of 10).

A positive integrated test is not diagnostic. It just gives the mother a chance to decide on whether to have a definitive diagnostic test i.e. a CVS or amniocentesis.

About 10% of those with a ‘positive’ integrated tests will be found to have a baby with Down’s syndrome. This means 9 out of 10 pregnancies with a positive integrated test result will have babies that are not actually affected.

The strength of the integrated test lies in the fact that it hardly misses an affected pregnancy detecting almost 90% of them.

A failed Integrated Test

About 1 in 10 of pregnancies where the baby has Down’s syndrome will be missed by the ‘Integrated Test’. This means, it is still possible to have a baby affected by Down’s syndrome even after a negative test. However, the chances of this happening are markedly reduced when this test is used compared to the older tests discussed above.

What is crucial here is that, to benefit from this clearly superior screening test, a mother needs to book early for her antenatal care. This is because the first phase needs to be performed in the first trimester i.e. before 13 completed weeks of gestation.

Miscarriage following amniocentesis

Approximately 1 in 200 mothers who undergo amniocentesis will miscarry as a consequence. This is about 0.5%.

Latest studies indicate that procedure-related miscarriage rate may actually be a lot lower than this. An authoritative study concluded in 2006 quoted a figure of 0.06%, which is almost 10 times lower than the traditionally quoted figure.

Be that as it may be, the sad fact is, some babies will be lost as a result of the procedure. What is more, some of these babies lost do not have chromosomal defects. It is up to the mother and her partner to decide whether the risk is worth taking.

Once diagnosis of Down’s syndrome is confirmed...

It is again up to the parents to decide what to do. In fact, this is an area that should be sorted out well before even the amniocentesis has taken place. Many parents of affected fetuses opt for termination of pregnancy. Others opt to continue with the pregnancy and value the fore-warning which prepares them to look after a handicapped child.

Screening for Down’s syndrome in a Twin Pregnancy

There are some unique problems here. If the screening blood test is performed before the twin nature of the pregnancy is recognized, as is occasionally the case, the results will almost certainly be misleading.

Such an error is recognized when an ultrasound scan is performed, which will establish the status. A scan is usually the next test in case of any abnormal result. The results are usually recalculated in the light of the new information to take into account the presence of more than one fetus in the womb.

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