Q: I AM pregnant for the first time and am worried about my baby's health. I have a recurrent nightmare that my baby is deformed. I am in my early 40s. I would like to know all the tests I can have to ensure my baby is OK.
I am 10 weeks pregnant now. Can you please outline the importance and risks of the various tests. After many discussions with my doctor, my husband and I are confused and frightened. Dr Rose writes: There are several tests which can be done to assess the health of your baby. Which ones you decide to have depend on the stage of your pregnancy, the presence of certain medical risk factors such as a family history of mental retardation, neural tube defects, genetic abnormalities and other hereditary diseases.
CVS, chorionic villi sampling, is usually done between eight to 10 weeks, by the insertion of a flexible catheter through the vagina and cervix to the site of foetal implantation. This procedure is done using ultra-sound guidance. A sample of the villi is drawn into a syringe and sent for analysis, which takes from 10 days to two weeks.
The DNA is extracted from the cultured cells and sent for molecular genetic analysis. The major advantage of this procedure is that it is done at a relatively early stage of pregnancy so that definitive results regarding genetic abnormalities are known early. Elective abortions for fatal genetic abnormalities may be carried out while the woman is still in the first trimester. The procedure carries a miscarriage rate of around one to two per cent.
There is a slight possibility that the results will not be conclusive. In this case an amniocentesis, which is performed at a later stage of pregnancy, may be recommended.
Amniocentesis is usually done between 14 and 18 weeks by insertion of a needle into the abdominal wall under the guidance of ultra-sound. The fluid and cells are extracted and sent for culture and analysis, which takes 10 days to two weeks. This is the most accurate and sensitive method of detecting foetal chromosomal abnormalities. However, by the time the results are obtained, the woman is already well into her second trimester and this makes any contemplation of an abortion difficult and dangerous.
The most common complication arising from the procedure is a slight amniotic fluid leak and haemorrhage. This occurs in one to two per cent of such examinations. The leak, or haemorrhage, usually stops after a period of bed rest. The risk of foetal loss is estimated at around 0.5 per cent.
