Edwards Syndrome (Trisomy 18)
Edwards Syndrome, also known as Trisomy 18, is a chromosomal condition caused by an additional copy of chromosome 18. Prenatal screening, detailed ultrasound and appropriate genetic testing can help identify pregnancies with an increased chance of Trisomy 18 and provide parents with clear information about further evaluation.
Edwards Syndrome is a genetic condition caused by an extra copy of chromosome 18. It is also called Trisomy 18. The additional chromosome can affect the development of multiple organs and body systems during pregnancy.
Trisomy 18 may be suspected during pregnancy when prenatal screening or ultrasound identifies findings associated with a chromosomal abnormality. A screening result indicates an increased or decreased chance and does not by itself confirm that the fetus has Edwards Syndrome.
First-trimester assessment can include an ultrasound examination, nuchal translucency measurement, maternal factors and blood-based screening. Combined first-trimester screening may use maternal age and history together with ultrasound and biochemical markers such as free beta-hCG and PAPP-A to estimate the chance of common chromosomal conditions including Trisomy 18.
Nuchal translucency, or NT, is the measurement of fluid at the back of the fetal neck during a specialized first-trimester ultrasound. An increased NT can be associated with chromosomal conditions, including Trisomy 18, as well as structural and cardiac abnormalities. An increased NT does not by itself establish a diagnosis of Edwards Syndrome.
Non-Invasive Prenatal Testing, also called NIPT, NIPS or cell-free DNA screening, uses a maternal blood sample to analyse DNA fragments originating mainly from the placenta. Cell-free DNA screening can assess the chance of common chromosomal conditions, including Trisomy 18.
NIPT is a highly effective screening method for common fetal aneuploidies, including Trisomy 18. A high-risk result means that the chance of Trisomy 18 is increased, but it is not the same as a confirmed diagnosis. Further ultrasound assessment and diagnostic testing may be recommended.
Detailed ultrasound may identify several structural findings associated with Trisomy 18. These can involve the brain, face, heart, limbs, kidneys, abdomen and fetal growth. The combination and severity of findings can vary from one pregnancy to another.
Some fetuses with Trisomy 18 may have abnormalities involving brain development. Ultrasound can assess the fetal brain and other central nervous system structures and may identify findings that increase suspicion of a chromosomal condition.
Ultrasound examination may identify certain facial or craniofacial differences in pregnancies affected by Trisomy 18. These findings are assessed together with the rest of the fetal anatomy rather than being considered diagnostic on their own.
Congenital heart abnormalities are frequently associated with Trisomy 18. A detailed assessment of the fetal heart is therefore an important part of evaluation when Trisomy 18 is suspected. Depending on the findings, a dedicated fetal echocardiography may also be recommended.
Certain limb and skeletal abnormalities can occur in fetuses with Trisomy 18. Detailed ultrasound evaluates the long bones, hands, feet and overall fetal structure to identify findings that may contribute to the clinical assessment.
Ultrasound can also assess the fetal kidneys, bladder, stomach, abdominal wall and other abdominal structures. Abnormal findings in these areas may occur in pregnancies affected by Trisomy 18 and can help guide further fetal assessment.
Fetal growth may be affected in pregnancies with Trisomy 18. Serial ultrasound examinations can be used when clinically appropriate to monitor fetal growth, amniotic fluid and other aspects of pregnancy wellbeing.
Ultrasound can identify structural findings that increase the suspicion of Trisomy 18, but ultrasound alone cannot definitively diagnose a chromosomal condition. Conversely, a normal ultrasound cannot completely exclude every chromosomal or genetic condition.
Diagnostic genetic testing can determine whether the fetus has a chromosomal abnormality such as Trisomy 18. Depending on the gestational age and clinical circumstances, chorionic villus sampling (CVS) or amniocentesis may be considered after appropriate counselling.
Chorionic villus sampling involves obtaining a small sample of placental tissue for genetic analysis. CVS can provide diagnostic information about chromosomal conditions such as Trisomy 18. The procedure is generally performed under ultrasound guidance and is discussed individually with the parents.
Amniocentesis involves obtaining a small amount of amniotic fluid for genetic testing. The fetal cells present in the sample can be analysed for chromosomal abnormalities, including Trisomy 18. The timing and suitability of amniocentesis depend on the individual pregnancy.
A high-risk NIPT result for Trisomy 18 does not automatically confirm Edwards Syndrome. The result should be reviewed with a fetal medicine specialist or genetic counsellor. Detailed ultrasound and diagnostic testing can be discussed to establish whether the chromosomal condition is present.
A low-risk NIPT result substantially reduces the chance of the screened chromosomal conditions, including Trisomy 18. However, NIPT does not screen for every genetic or structural condition, so recommended ultrasound examinations and routine pregnancy care remain important.
The second-trimester detailed anomaly scan evaluates fetal anatomy including the brain, face, spine, heart, abdomen, kidneys, limbs, placenta and amniotic fluid. This examination remains important even when prenatal screening has already been performed because ultrasound can identify structural abnormalities that may not be detected through chromosome screening alone.
When Trisomy 18 is suspected or a cardiac abnormality is identified, detailed evaluation of the fetal heart may be recommended. Fetal echocardiography provides a more focused assessment of cardiac anatomy and function and can contribute to pregnancy counselling and planning.
Trisomy 18 screening can also be performed in twin pregnancies, although screening methods and interpretation may differ from singleton pregnancies. Ultrasound assessment of each fetus is important, particularly when there are differences in growth or structural findings between the twins.
Genetic counselling helps parents understand the difference between screening and diagnostic testing, the significance of ultrasound findings, available testing options and the limitations of each test. Counselling can be especially valuable when prenatal screening or ultrasound indicates an increased chance of Trisomy 18.
When diagnostic testing confirms Trisomy 18, parents can receive individualized counselling regarding the fetal findings, pregnancy monitoring, available medical support and pregnancy care options. Management depends on the gestational age, ultrasound findings, overall pregnancy circumstances and the family's informed preferences.
Early fetal medicine assessment can help identify concerning ultrasound findings and provide timely access to appropriate screening, diagnostic testing and specialist counselling. A structured evaluation helps parents understand the available information and make informed decisions about pregnancy care.
At Promise Fetal Medicine & Pregnancy Scan Centre in Jalandhar, prenatal assessment for suspected Trisomy 18 may include first-trimester ultrasound, nuchal translucency assessment, NIPT counselling, detailed fetal anomaly scanning, fetal heart assessment and guidance regarding appropriate diagnostic genetic testing.
If you have received a high-risk screening result, an abnormal ultrasound finding or another report suggesting Trisomy 18, a fetal medicine consultation can help you understand the findings and available next steps. Specialist assessment can provide individualized information and support throughout the pregnancy.
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Edwards syndrome, also known as Trisomy 18, is a chromosomal condition caused by an extra copy of chromosome 18. It can affect the development of multiple organs and body systems and may be associated with significant pregnancy and newborn complications. During pregnancy, screening options such as NIPT (Cell-Free DNA), first-trimester screening, and ultrasound can help assess the likelihood of Trisomy 18. At Promise Fetal Medicine & Pregnancy Scan Centre in Jalandhar, detailed fetal assessment and appropriate prenatal screening can help identify pregnancies that may require further evaluation. Screening results indicate risk and do not by themselves confirm Edwards syndrome; diagnostic testing may be advised when appropriate.
Director and Chief Fetal Medicine Specialist
Baby's Journey Through Pregnancy
