Diagnostic tests                                                                             Midwife Claire Parry

There are various diagnostic tests available during pregnancy.

Some are offered depending on your age. Older mothers are more likely to have babies with problems. Some will be offered as the result of a high risk screening test.

Diagnostic tests are reliable ways of giving you information about the health of your baby. It will give you a definite false or positive result.

There are two tests that are most commonly used.

Chorionic Villus Sampling (CVS) can be used any time

after the tenth week of pregnancy. It is the collecting of placental tissue under very controlled conditions.

It is carried out one of two ways. Firstly, it can be done vaginally through the cervix. While the abdomen is being scanned, a catheter is passed through the cervix and  the tissue required is aspirated through it.

Secondly, the tissue can be taken through the abdomen. This time using a needle and a scan will again be in progress at the time.

The tissue is sent to a lab and you will get an initial result which is a chromosome count within 24-48

hours.The cells are then sent for culture and you will get a confirmed result within 14-21 days.

Amniocentesis is the collection of the amniotic fluid from around the baby. It is achieved by the insertion of a fine needle through the abdomen under the guidance of an ultrasound scan.

It is usually carried out after the 15^th week of pregnancy. The fluid contains cells that have been shed by the foetus from various places such as the skin and lungs. These are analysed to give the results.

As with CVS, you will receive initial results and then confirmed

results. The procedure carries a miscarriage rate of 1%. For every 100 amniocentesis tests, one pregnancy will be lost.

Amniocentesis is more commonly available as more obstetricians are trained to use it. However, both tests provide reliable results.

If you are considering accepting one of these tests, then you will be offered counselling before and after the procedure. The results of the test could mean that you and your partner have a difficult decision to make and you need to be supported through that.