Prenatal diagnosis
There are many reasons behind the ever-decreasing size of families and economic and social factors probably play the biggest role.
One of the results of this lower birth rate is the expectation of parents that the children they do choose to have are healthy, both physically and mentally.
With the advances in medical technologies, a doctor can now diagnose conditions affecting babies while they are still in the womb. And although many birth defects cannot be prevented, proper treatment can be planned for mother and baby.
PRENATAL DIAGNOSIS CAN BE |PERFORMED BY THE FOLLOWING METHODS:
ULTRASOUND
Ultrasound helps an obstetrician to see the baby in the womb and it has now become a widely accepted and safe tool. Ultrasound can be used at any stage of the pregnancy and is able to help detect birth defects, including abnormalities of the baby’s face and neck (such as a cleft lip), heart valve disease, abnormalities of the head and spinal cord (such as hydrocephalus and spina bifida), gastrointestinal abnormalities (such as stenosis of the oesophagus, abdominal wall defects), urinary tract abnormalities (such as renal agenesis and hydronephrosis), and structural abnormalities (such as short arms-legs, or clubfoot). Recently, a modern 4D ultrasound technology has been developed to create motion pictures of the foetus as well.
MATERNAL SERUM SCREENING TEST
Foetal proteins excreted in the mother’s blood can be measured from a blood test taken from the mother between 16-18 weeks of pregnancy. This test can detect foetal chromosome abnormalities such as Down Syndrome in the foetus of pregnant mothers younger than 35 years old. The mother’s blood can be examined for levels of Maternal Serum Alpha – Fetoprotein (MSAFP). A high level of MSAFP means that the baby has spina bifida and there is a sac affecting the spinal column. A low level of MSAFP could indicate Down Syndrome. A Triple Test is used to measure the levels of MSAFP, Human Chorionic Gonodotropin (HCG) and Estriol (E3). This test is used to screen for Down syndrome babies in the womb.
PREIMPLANTATION GENETIC DIAGNOSIS: PGD
PGD is a technique used to identify genetic defects in embryos before pregnancy. It is a process of removing a cell from an in vitro fertilisation embryo for biomolecular analysis prior to transferring screened embryos to the uterine cavity. This technique is used to diagnose chromosomal abnormalities, like Down syndrome, and genetic disorders, like thalassaemia. PGD is used for couples at risk of having a child with a genetic disease.
AMNIOCENTESIS
Amniocentesis is a medical procedure mostly used to detect chromosomal abnormalities in the foetus, like Down syndrome, and genetic disorders, like thalassaemia. The procedure involves drawing amniotic fluid through the mother’s stomach under continuous ultrasound monitoring and control. Approximately 15-20 ml of amniotic fluid is removed for laboratory testing and the results usually take about 3-4 weeks. Amniocentesis is performed when the mother is between 16-18 weeks pregnant. The common indicators for amniocentesis to be performed are:
-Mother who are 35 years or older at delivery
-A previous child with chromosomal abnormalities
-Father/mother or blood relatives with chromosomal abnormalities
-History of recurrent miscarriage
-Abnormal results of mother’s blood test
-Foetal malformations identified from ultrasound
CORDOCENTESIS
With this procedure, a needle is inserted into the umbilical cord to retrieve foetal blood through the mother’s stomach. The procedure is carried out under ultrasound monitoring and control. The blood sample is then sent to a laboratory to check for chromosomal abnormalities, like Down Syndrome, and to diagnose genetic diseases, like thalassaemia, as well as congenital infections, such as Rubella and Toxoplasma, which cause defects or even death for the foetus in the womb. Cordocentesis is performed when the mother is 18 weeks pregnant or more, and has the same diagnostic indications as amniocentesis.
Prenatal Diagnosis is an option for couples at risk of having a child with a disease and enables them to know if the foetus is affected so that treatment can be planned in advance.
DR THEWIN DEJTHEVAPORN is an OB/GYN and Maternal Foetal Medicine Specialist with Samitivej Sukhumvit Hospital’s Women’s Health Centre. |Call (02) 711 8555-6.
