In this week’s health talk, The Pioneer’s SHIKHA DUGGAL Discusses in detail about prenatal genetic testing as she converses with some experts in the field.
Pregnancy is a time of great anticipation and, sometimes, anxiety. You might worry that your baby will have health problems. While most babies are born healthy, it’s important to understand your options for obtaining details about your baby’s health. So for this week’s Health Talk, we plummet into something called prenatal genetic testing!
“Prenatal genetic testing refers to a variety of medical tests and procedures performed during pregnancy to assess the genetic health of the developing fetus.These tests can identify the presence of genetic disorders or chromosomal abnormalities. Genetic disorders are conditions caused by changes or mutations in a person’s DNA.These changes can lead to health problems, developmental issues, or other medical conditions.
Examples include Down syndrome, cystic fibrosis, and sickle cell anaemia,” informed Dr. M. Rajini, an obstetrician and gynaecologist from Care Hospitals, Banjara Hills.
First-trimester screening is a specific type of prenatal genetic testing conducted during the early stages of pregnancy, typically between weeks 11 and 14. It combines a blood test and an ultrasound to assess the risk of chromosomal abnormalities such as Down syndrome and trisomy 18. “The results of prenatal screening tests are usually reported as a probability or risk assessment.
First-trimester screening is a specific type of prenatal genetic testing conducted during the early stages of pregnancy, typically between weeks 11 and 14. It combines a blood test and an ultrasound to assess the risk of chromosomal abnormalities such as Down syndrome and trisomy 18. “The results of prenatal screening tests are usually reported as a probability or risk assessment.
A low-risk result typically means a lower likelihood of the foetus having a genetic disorder, while a high-risk result indicates a higher probability. Follow-up diagnostic tests may be recommended for high-risk results to confirm or rule out the condition. The accuracy of prenatal genetic screening tests can vary depending on the specific test used and the gestational age at which it’s performed.
Generally, they provide a good screening tool to assess the risk of genetic disorders, but they are not diagnostic. Diagnostic tests like amniocentesis or chorionic villus sampling are more accurate for confirming or ruling out genetic conditions. It’s important to discuss the accuracy and implications of these tests with a healthcare provider during pregnancy,” added the medical expert.
These tests can help parents-to-be and healthcare providers make informed decisions about the pregnancy and prepare for the potential health needs of the child. Prenatal genetic testing includes two types of tests: screening tests and diagnostic tests. Common prenatal genetic tests include ultrasound examinations, blood tests, and invasive tests like amniocentesis or chorionic villus sampling (CVS).
“Genetic disorders are conditions that result from abnormalities in an individual’s DNA, typically caused by mutations or changes in specific genes or chromosomes. These disorders can be inherited from one’s parents or occur spontaneously. NIPT is highly accurate for detecting common chromosomal abnormalities like Down syndrome. It typically has a sensitivity of over 99% and a low false-positive rate.
Another one combines a blood test and an ultrasound. It can accurately identify a significant proportion of pregnancies at increased risk for certain chromosomal abnormalities, but it may also have false-positive results. Quad Marker or Triple Marker Screening are prenatal blood tests that are less accurate than NIPT but can still provide valuable information about the risk of certain genetic conditions.Remember that while screening tests can indicate an increased risk, they do not provide a definitive diagnosis.
If screening suggests an increased risk, further diagnostic testing like amniocentesis or chorionic villus sampling is recommended for confirmation. The accuracy of diagnostic tests is much higher as they directly examine the foetus’s genetic material. Always consult with a healthcare provider to understand the specific accuracy and implications of the screening tests used,” enlightened Dr. Shravya Tallapureddy, a senior consultant at Ferty 9 Fertility Center. Nowadays, routine first-trimester screening has become the norm since the age of expectant mothers is also increasing. There is no right or wrong answer when it comes to prenatal genetic testing!
Prenatal screening tests provide various results that are used to assess the risk of chromosomal abnormalities in the developing fetus. A screen-positive result indicates that the screening test has identified a higher-than-average risk of a specific genetic or chromosomal condition in the fetus. It’s important to note that a screen-positive result does not provide a definitive diagnosis. It signifies an increased likelihood of risk, but further testing is typically needed to confirm whether the condition is actually present.
In the case of a screen-positive result, healthcare providers often recommend follow-up diagnostic tests or amniocentesis to obtain more definitive information about the baby’s genetic status. A screen-negative result indicates that the screening test has not identified a higher-than-average risk of the specific genetic or chromosomal condition being screened for. While a screen-negative result is reassuring, it does not guarantee that the foetus is free from all genetic or chromosomal abnormalities.
These tests have limitations and might not detect every possible condition. Expectant parents should discuss the implications of a screen-negative result with their healthcare provider, as further testing or monitoring may still be recommended based on other factors, such as family history or other risk factors.
“A screen-positive result does not necessarily mean the baby has a genetic condition, and a screen-negative result does not guarantee a completely healthy pregnancy. Expectant parents should have thorough discussions with their healthcare providers to understand the results, their implications, and the available options for further testing or interventions. In addition, the decision to pursue further testing or interventions should be based on individual circumstances, preferences, and informed choices made in consultation with health professionals,” explained Dr. Sowmya Sampura Maddipati, a high-risk pregnancy specialist.
