The importance of pre-screening

Many expectant mothers are familiar with just one aspect of the pre-screening process — the ultrasounds they are required to do at intervals during pregnancy. But there are many other prenatal tests available, tests that might help prepare you for some of the challenges your baby may have at birth.

Prenatal screenings are done for a variety of reasons and at various stages of a woman’s pregnancy. They could be done to test for inherited diseases, to detect foetal abnormalities or risks, to monitor the progress of the pregnancy, and to determine the baby’s readiness for birth.

The need to screen is usually determined by a number of factors. One of the most crucial factors is the age of the mother.

Once the mother is over 35, then she should be screened. If she has had a previous history of a baby that is abnormal, or has any abnormalities herself, then she should be screened.

The first screening can be done as early as between nine to 11 weeks. At this point, nuchal translucency screening can be done to determine whether your baby is at risk for Down’s Syndrome. An amniothentisis could then be done between 14 to 16 weeks to diagnose chromosomal abnormalities and foetal infections.

There are still debates as to whether babies should be pre-screened for other abnormalities, especially those that cannot be corrected from within the womb, while others laud the ever-changing technologies that are making prenatal screening much more possible.

Some people screen as a way of planning to care for the child when the child is delivered. Others just don’t want to know.

Down’s Syndrome is usually the disorder most commonly detected through pre-screening. However, a mother could be screened to determine whether she has cystic fibrosis, HIV/AIDS, gestational diabetes, anaemia, chromosomal disorders and check for potential incompatibility in blood types. Doctors, however, are yet to come up with a routine test that can detect neurodevelopment disorders such as autism from within the womb.

For structural abnormalities, the doctors would do an anomaly scan, where the radiologist would look from the head, straight down to the toes, looking for any abnormalities — whether the skull bone is complete [and] whether or not both eyes are there. They look at the heart to make sure that it has four chambers and if the valves are working correctly, that the abdomen is complete, that all the fingers and toes are there.

The anomaly scan is usually done between 18 to 20 weeks while an ultrasound usually takes place between 18 to 22 weeks. In addition to the blood test, this method is used to check for congenital abnormalities that are related to genetics.

The anomaly scan also helps doctors decide whether or not the baby will be able to be delivered vaginally. Mothers may need to have a plastic surgeon or the paediatric surgeon on standby depending on what the anomaly is.