For Patients
Understanding Genetic Tests
A Simple Guide for Everyone
Genes are like instruction manuals in every cell of our body.
Genetic tests help doctors read these instructions to understand, diagnose, treat, and prevent many health conditions.
Accurate
Scientifically validated testing
Advanced
State-of-the-art technology
Expert Guidance
Genetic counselling at every step
Better Outcomes
Informed decisions for healthier lives
Prenatal Genetic Tests Explained in Details
Non-Invasive Prenatal Testing (NIPT)
What Is It? A blood test performed on the mother that analyses small fragments of the baby's DNA circulating in maternal blood.
When Is It Performed?
- From 10 weeks of pregnancy onwards
What Is Analysed?
- Cell-free fetal DNA (cffDNA) in maternal blood plasma
Sensitivity
- Greater than 99% for common chromosomal conditions screened
Key Points
- Safe and non-invasive
- Requires only a maternal blood sample
Nuchal Translucency Scan (NT Scan)
What Is It? An ultrasound scan that measures the fluid-filled space at the back of the baby's neck during early pregnancy.
When Is It Performed?
- 11 weeks to 13 weeks + 6 days of pregnancy
Where Is It Done?
- Fetal Medicine Specialist Experienced - trained Sonologist
Sensitivity
- 70–75% when performed alone
Key Points
- Safe and non-invasive
Dual Marker Test
What Is It? A maternal blood test performed together with the NT scan during the first trimester.
When Is It Performed?
- 11 weeks to 13 weeks + 6 days of pregnancy
What Is Measured?
- Free β-hCG
- PAPP-A (Pregnancy-Associated Plasma Protein A)
Sensitivity
- 85–90% when combined with the NT scan
Key Points
- First-trimester screening test
Anomaly Scan (Detailed Ultrasound)
What Is It? A detailed ultrasound that evaluates the baby's growth, organs, and structural development.
When Is It Performed?
- 18–22 weeks of pregnancy
Where Is It Done?
- During an ultrasound examination by a trained sonologist
What Does It Detect?
- Structural anomalies in the baby
Key Points
- Safe and non-invasive
- Important for fetal well-being
Chorionic Villus Sampling (CVS)
What Is It? An invasive procedure in which a small sample of placental tissue is collected for genetic analysis.
When Is It Performed?
- 11–13 weeks of pregnancy
Where Is the Sample Obtained From?
- The placenta (chorionic villi) under ultrasound guidance
Diagnostic Accuracy
- Greater than 99% for the conditions being specifically tested
Key Points
- Provides an early diagnosis
Follow-up
- Followed by genetic testing prescribed by your clinician or genetic Counselor
Amniocentesis
What Is It? An invasive procedure in which a small amount of amniotic fluid surrounding the baby is collected for testing.
When Is It Performed?
- 15–20 weeks of pregnancy
Where Is the Sample Obtained From?
- The amniotic fluid around the baby under ultrasound guidance
Diagnostic Accuracy
- Greater than 99% for the conditions being specifically tested
Key Points
- Provides highly accurate diagnostic information
Follow-up
- Followed by genetic testing prescribed by your clinician or genetic Counselor
Quadruple Marker Test
What Is It? A second-trimester blood test that measures four substances produced during pregnancy.
When Is It Performed?
- 15–22 weeks of pregnancy, ideally between 16–18 weeks
What Is Measured?
- AFP (Alpha-Fetoprotein)
- Total hCG
- uE3 (Unconjugated Estriol)
- Inhibin A
Sensitivity
- 75–80%
Key Points
- Useful when first-trimester screening was not performed
Screening vs Diagnostic Tests
Screening
Tests
(Estimate Risk)
- NIPT
- NT Scan
- Dual Marker Test
- Anomaly Scan
- Quadruple Marker Test
These tests estimate the chance of a condition being present.
Diagnostic
Tests
(Provide Definitive Answer)
- CVS
- Amniocentesis
These tests determine whether a condition is actually present.
Followed by genetic testing prescribed by your clinician.
Prenatal Testing Timeline
Important to Know
- Screening tests estimate risk; they do not diagnose a condition.
- Diagnostic tests provide a definitive answer for the conditions being specifically analysed.
- The choice of prenatal testing should always be made after discussion with your healthcare provider or genetic counsellor.