Antenatal Risk Assessment

First & Second Trimester Antenatal Risk Assessment

Also known as OSCAR (One-Stop Clinic For Assessment of Risk for Fetal Anomalies), this screening test can help detect possibilities of fetal anomaly, in particular Down Syndrome.

Diagnostic tests such as amniocentesis or chorionic villus sampling are the only way to be certain of chromosome abnormalities. However, these tests are associated with a risk of miscarriage. Fortunately, there are screening tests available to help determine the chance of the fetus having specific chromosomal abnormalities like Trisomy 21 (Down Syndrome), Trisomy 18 (Edward’s Syndrome) and Trisomy 13 (Patau Syndrome). Knowing this, couples can then better decide whether they wish to proceed with more invasive diagnostic tests.

First Trimester Screening (FTS)

FTS combines maternal blood testing with an ultrasound evaluation of the fetus. This is performed between 11 - 14 weeks of pregnancy and the detection rate for chromosomal abnormalities is 90%.

  • The ultrasound scan measures Nuchal Translucency (NT) which is a collection of fluid under the skin behind the baby’s neck in the first trimester of pregnancy. Down Syndrome babies tend to have a thicker than average NT. Results from this scan, the blood test and the mother’s age will determine the chances of chromosome abnormality.
  • In addition to this, an ultrasound assessment of the nasal bone at 11 - 14 weeks improves the accuracy of screening for Down Syndrome. The absence of a fetal nasal bone, along with a thickened NT, is associated with a higher chance of having a baby with Down Syndrome.
First Trimester Screening (FTS)

Normal nasal bone and nuchal translucency
(Low risk of Down Syndrome)

First Trimester Screening (FTS)

Normal nasal bone and nuchal translucency
(Low risk of Down Syndrome)

Second Trimester Screening

Maternal serum screening is a blood test conducted between 15 - 20 weeks of pregnancy to aid in the risk assessment of Down Syndrome. The blood test measures the amount of human chorionic gonadotrophin (hCG) and alpha-fetoprotein (AFP) which are produced by the fetus and the placenta. These results are combined with the mother’s age to calculate the chance of having a baby with Down Syndrome.

Non-Invasive Prenatal Testing (NIPT)

NIPT is a new test to screen for genetic conditions such as Down Syndrome and other specific genetic disorders. There is no risk to the mother and fetus as it involves analyzing a sample of the mother’s blood for cell-free fetal DNA.

We understand your concerns and are committed to supporting you every step of the way.
Our Specialist
Dr Regina Zuzarte-Ng

MBBS (Singapore), MMed (O&G) (Singapore), FRCOG (UK), FAMS (Singapore)

Dr Regina is skilled in the management of prenatal care and gynaecological conditions. A mother to two, she understands the needs of women intimately and incorporates that into her practice.

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