Are there any risks?

There are risks involved with the CVS test, although complications are rare.

• Miscarriage

Research shows that there is a slightly higher risk of miscarriage when a CVS test is performed but studies have proven to be inconclusive and some suggest there is no significant difference between the risk of miscarriage between those who have the test and those who do not. The Royal College of Obstetricians and Gynaecologists asserts that the risk of miscarriage following the CVS test is around 2 percent.

• Infection

There is a risk of infection, as with all surgical procedures. The risk of serious infection is extremely low and is thought to be around 1 in 1,000. Infections can be caused by bacteria entering the body via the instruments.

• Test failure

In some cases, the test fails to get the sample it needs either because too few cells have been collected or because the sample was contaminated by the mother’s cells; if this happens, the test will be repeated. It is estimated that around 2-5 percent of tests have to be repeated.

• Rhesus sensitisation

This occurs as a result of the baby and mother’s blood mixing if they have different blood types; for example, if the baby is rhesus-positive and the mother is rhesus-negative. Rhesus sensitisation causes the mother’s body to create antibodies to attack the baby’s blood which has entered the mother’s bloodstream. This condition must be treated with an injection of anti-D immunoglobulin, otherwise it may develop into rhesus disease.