Down Syndrome

What Is Down Syndrome?

Down Syndrome, also known as Trisomy 21, occurs when a baby has an additional copy of chromosome 21. It can affect physical development, learning, and certain aspects of health. The condition occurs in pregnancies across different age groups and cannot be diagnosed from ultrasound alone.

Down Syndrome and Pregnancy

During pregnancy, screening can estimate the chance that a fetus has Down Syndrome. Screening does not provide a definite diagnosis. A higher-risk screening result may be followed by genetic counselling, detailed ultrasound assessment, and, when appropriate, diagnostic testing.

First-Trimester Screening for Down Syndrome

First-trimester screening commonly includes an ultrasound examination with measurement of nuchal translucency (NT), together with maternal factors and, depending on the screening method, blood markers such as free beta-hCG and PAPP-A. This information can be combined to estimate the chance of common chromosomal conditions including Trisomy 21.

Nuchal Translucency (NT) Scan

Nuchal translucency is a measurement of fluid at the back of the fetal neck obtained during a specific first-trimester ultrasound examination. An increased NT can be associated with chromosomal conditions such as Down Syndrome, as well as certain structural or cardiac abnormalities. However, an increased NT does not by itself mean that the baby has Down Syndrome.

NIPT for Down Syndrome

Non-Invasive Prenatal Testing (NIPT), also called NIPS or cell-free DNA screening, analyses placental DNA fragments found in the mother's blood. It is widely used to screen for common chromosomal conditions, including Trisomy 21. NIPT is a screening test and a high-risk result generally requires confirmation through an appropriate diagnostic test.

How Accurate Is NIPT for Down Syndrome?

NIPT has a high screening performance for Trisomy 21, but it is not a diagnostic test. Results can occasionally be affected by factors related to the placenta, pregnancy, maternal health, or laboratory testing. Your fetal medicine specialist can explain what a particular result means in the context of your ultrasound and pregnancy history.

Combined First-Trimester Screening

Combined screening may use maternal age, ultrasound findings including NT measurement, and maternal blood markers. The information is used to calculate an individualized risk for chromosomal conditions such as Down Syndrome, Trisomy 18, and Trisomy 13.

Ultrasound Markers of Down Syndrome

Detailed ultrasound may identify certain findings that are associated with an increased chance of chromosomal abnormalities. These may include increased NT or particular structural findings and ultrasound markers. Such findings are interpreted together with the overall clinical and genetic assessment rather than being considered a diagnosis on their own.

Can Ultrasound Diagnose Down Syndrome?

Ultrasound cannot definitively diagnose Down Syndrome. Some fetuses with Down Syndrome may have ultrasound findings, while others may have no obvious abnormality on routine scanning. When screening or ultrasound indicates an increased chance, additional genetic evaluation may be recommended.

Diagnostic Testing for Down Syndrome

Diagnostic testing can determine whether the fetus has a chromosomal abnormality. Depending on the pregnancy stage and clinical situation, tests such as chorionic villus sampling (CVS) or amniocentesis may be considered. These procedures obtain fetal or placental material for chromosome analysis and are different from screening tests.

What If Screening Shows a High Chance?

A high-risk screening result does not automatically mean that the baby has Down Syndrome. The next step may include a detailed ultrasound, review of the screening result, genetic counselling, and discussion of diagnostic testing. The appropriate approach depends on the individual pregnancy and the family's preferences.

What If NIPT Shows a Low Chance?

A low-chance NIPT result substantially reduces the likelihood of the chromosomal conditions included in the test, but it does not rule out every genetic or structural condition. Routine pregnancy care and recommended ultrasound examinations remain important.

Down Syndrome Screening in Twin Pregnancy

Chromosomal screening is also possible in twin pregnancies, although the approach and interpretation can differ from singleton pregnancies. Cell-free DNA screening may be used in appropriate twin pregnancies, together with specialist ultrasound assessment and individualized counselling.

Why Is Early Screening Important?

Early screening gives parents information about the chance of common chromosomal conditions during pregnancy. When an increased chance is identified, there may be time for further assessment, diagnostic testing where appropriate, and informed counselling about the pregnancy.

Down Syndrome and Detailed Fetal Ultrasound

A detailed fetal ultrasound is an important part of prenatal assessment. It evaluates fetal anatomy, growth, placenta, amniotic fluid, and other relevant structures. Ultrasound findings are considered alongside screening and genetic information when assessing the overall pregnancy.

Genetic Counselling for Down Syndrome

Genetic counselling can help parents understand screening results, available diagnostic tests, possible outcomes, and the limitations of each test. Counselling is particularly useful when an ultrasound finding or screening result suggests an increased chance of a chromosomal condition.

Down Syndrome Screening in Jalandhar

At Promise Fetal Medicine & Pregnancy Scan Centre in Jalandhar, fetal medicine assessment can include first-trimester ultrasound, nuchal translucency assessment, prenatal screening review, NIPT counselling, detailed fetal ultrasound, and guidance regarding further genetic evaluation when required.

Book a Down Syndrome Screening Consultation

If you are looking for Down Syndrome screening during pregnancy, a fetal medicine consultation can help you understand which screening or diagnostic options may be appropriate for your pregnancy. Early assessment and individualized counselling can provide clear information to support informed pregnancy care.