The prenatal diagnostics available at Mount Elizabeth Hospital range from early trimester screening to mid-trimester serum screening for Down syndrome. When the foetus is suspected of having a birth defect, growth restriction, or when the pregnancy is high risk due to the mother’s physical condition and age, we are fully equipped to diagnose and monitor the situation. We use high quality 2D foetal imaging, growth surveillance and biophysical foetal assessment, as well as foetal blood sampling or amniotic fluid aspiration to detect any infection or inherited disorders.
Our prenatal diagnostics services include:
Foetal anomaly scan
An ultrasound scan at around 18 - 20 weeks to check for foetal congenital anomalies, this is sometimes called the mid-pregnancy scan. At this stage, the foetus is large enough and the major organ systems are also adequately formed to be inspected. During the scan, the baby will be checked on the following:
- Shape of the head and the brain structures
- Correct alignment of the spine and that the skin covers the spine
- Long bones of the limbs, heands and feet, fingers and toes.
- Cleft lip
- Size and symmetry of the heart chambers, heart valves and the orientation of the great blood vessels
- Kidneys and bladder
In addition, the position of the placenta and the sufficiency of amniotic fluid are also checked. This thorough examination of the foetal structures pick up major abnormal feature so that early action can be taken.
Also known as Amniotic Fluid Test (AFT), this is mainly performed to diagnose chromosomal abnormality. Common abnormalities include Down syndrome, Edwards syndrome and Turner syndrome. AFT is also performed to detect sex of the foetus, foetal lung maturity and foetal infection.
When doing AFT a small amount of local anaesthetic is first administered to relieve the pain felt during the insertion of the needle. Using the guidance of ultrasound, the needle is inserted through the mother’s abdomen, through the uterus wall and into the amniotic sac away. The needle will be placed safely away from the foetus and about 20ml of amniotic fluid is extracted.
For prenatal genetic diagnosis, the foetal cells in amniotic fluid sample will be cultured, fixed and stained, and the chromosomal make-up will be examined under the microscope. For diagnosing in-utero foetal infection, the amniotic fluid will be cultured for any growth of micro-organism.
Chorionic villus sampling
Chorionic villus sampling is a prenatal test usually done between 10 - 12 weeks of pregnancy, when a small sample of placental tissue (chorionic villus) is removed for analysis. The test can be performed in two ways, either through the cervix or through the abdomen. The advantage of chorionic villus sampling is that the result may be obtained earlier and further action, if necessary, can be taken quickly.
Foetal blood sampling
Foetal blood samply (FBS) is usually done between 20 - 23 weeks of pregnancy. During the procedure blood is drawn from the umbilical cord of the foetus. Similar to the AFT and CVS, a small hollow needle is inserted through the abdomen and uterus into the umbilical cord. FBS is generally conducted to detect for chromosomal disorders, genetic diseases and viral infections.