ಗರ್ಭಾವಸ್ಥೆಯ ಲ್ಯಾಬ್ ಪರೀಕ್ಷೆಗಳು
Aneuploidy Screening (Down Syndrome Screening) in Pregnancy
Assesses the risk of chromosomal conditions including Down syndrome
ಇದು ಏನನ್ನು ಅಳೆಯುತ್ತದೆ?
Aneuploidy screening assesses the probability that your baby has a chromosomal abnormality — most importantly Down syndrome (Trisomy 21, an extra copy of chromosome 21), Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome). These conditions occur when an egg or sperm carries an extra chromosome, resulting in 47 chromosomes instead of 46 in every cell of the baby. Screening tests estimate the probability using a combination of biochemical markers in your blood and ultrasound measurements — they do not give a definitive answer but identify who needs further testing.
ಇದನ್ನು ಯಾವಾಗ ಸೂಚಿಸಲಾಗುತ್ತದೆ?
First trimester combined screen: NT scan + Double Marker blood test at 11–14 weeks. Second trimester Triple Marker (AFP, hCG, unconjugated estriol) or Quad Marker (adds Inhibin A): 15–20 weeks. NIPT (Non-Invasive Prenatal Testing / cell-free DNA): from 10 weeks onwards — can be offered as a primary screen or following a high-risk conventional screen. Invasive testing (amniocentesis or CVS): offered when screening is high risk or when definitive chromosomal diagnosis is needed regardless of screening.
ಗರ್ಭಾವಸ್ಥೆಯಲ್ಲಿ ಸಾಮಾನ್ಯ ವ್ಯಾಪ್ತಿಗಳು
ಅಸಹಜ ಫಲಿತಾಂಶದ ಅರ್ಥವೇನು?
A high-risk screening result means the calculated probability of a chromosomal condition exceeds a threshold — it does NOT mean your baby has the condition. For example, a result of 1:50 means 1 in 50 babies with that result has Down syndrome — but 49 out of 50 do not. Screening has both false positives (high-risk result but baby is normal) and false negatives (low-risk result but baby is affected). A high-risk result is an indication to discuss further options: NIPT (if not already done) for very high accuracy, or invasive testing (CVS at 11–14 weeks, or amniocentesis at 15–20 weeks) for a definitive chromosomal diagnosis. Invasive tests carry a small procedure-related miscarriage risk (approximately 0.5–1%).
ದಕ್ಷಿಣ ಭಾರತದ ಮಹಿಳೆಯರಿಗೆ ಇದರ ಅರ್ಥವೇನು
The risk of chromosomal conditions increases with maternal age — from about 1:1000 at age 25 to 1:100 at age 40. Down syndrome screening is offered to all pregnant women, not only those above 35. In government hospitals across Karnataka, Tamil Nadu, Andhra Pradesh, and Kerala, first trimester screening is increasingly available. NIPT is available at private laboratories and typically costs ₹15,000–₹25,000; it is not yet universally covered by insurance. Government hospitals in some states offer free Triple Marker testing. Genetic counselling is strongly recommended before and after any screening or diagnostic test.
ಪದೇ ಪದೇ ಕೇಳಲಾಗುವ ಪ್ರಶ್ನೆಗಳು
What is the difference between a screening test and a diagnostic test?
A screening test estimates probability — it sorts women into low-risk and high-risk groups but does not give a definitive answer. Examples: NT scan, Double Marker, Triple Marker, NIPT. A diagnostic test gives a definitive chromosomal answer by examining actual chromosomal material from the baby. Examples: amniocentesis (sampling amniotic fluid) and CVS (chorionic villus sampling from the placenta). Diagnostic tests carry a small procedure risk; screening tests are risk-free.
My screening came back high risk. What should I do?
First: do not panic. A high-risk result does not mean your baby has the condition — the majority of high-risk screening results are false positives. Seek genetic counselling urgently. Your options include: NIPT (if not already done) — very high accuracy, non-invasive, but takes 10–14 days; or invasive testing (CVS or amniocentesis) for a definitive answer. Your doctor will help you weigh the options based on your specific risk figure, gestational age, and personal situation.
Is NIPT better than the NT scan + blood test?
NIPT has higher sensitivity (> 99%) and lower false-positive rate (< 0.1%) for Trisomy 21 compared to the combined first trimester screen (~90% sensitivity, 5% false-positive rate). However, NIPT is significantly more expensive, does not replace the NT scan (which also detects structural abnormalities and is not replaced by blood testing), and a positive NIPT still requires confirmatory invasive testing before any irreversible decision. Many guidelines now recommend NIPT as the most accurate non-invasive screening option if cost is acceptable.
I am 28 years old. Do I need Down syndrome screening?
Yes. Down syndrome occurs at all maternal ages — approximately 80% of Down syndrome births are to mothers under 35 because younger women have more pregnancies overall. Age alone is not a sufficient criterion to skip or mandate screening. Current guidelines recommend that all pregnant women, regardless of age, be offered information about chromosomal screening so they can make an informed choice.
What happens if Down syndrome is confirmed?
If invasive testing confirms Trisomy 21, you will be referred to a genetic counsellor and fetal medicine specialist for detailed counselling about the spectrum of outcomes in Down syndrome (most people with Down syndrome live full, meaningful lives), associated medical conditions to watch for (heart defects in 40-50%, which can be treated), and support resources. The decision about how to proceed with the pregnancy is entirely personal and you will be supported whatever you decide.