One Stop Clinic for Assessment of Risk for Down’s syndrome (OSCAR) is a screening method performed at 11-14 weeks of gestation. The following parameters are obtained to calculate the risks of having a Down’s baby for each individual woman:
● The woman’s age
● Her serum level of pregnancy-associated plasma protein-A (PAPP-A)
● Her serum level of free beta human chorionic gonadotropin (free-beta hCG)
● Thickness of the baby’s neck-fold (nuchal translucency thickness)


Advantages of OSCAR:
● High detection rate (90%);
● Ultrasound examination is safe to the baby;
● Suitable for women of any age;
● It can be performed in early gestation and hence there is plenty of time to make decision should the results be positive;
● If the baby is confirmed to be affected, there is still enough time to consider all management options;
● If a termination of pregnancy is chosen for an abnormal baby, it carries less risks to the women when performed in early gestation.


“Positive” OR “Increased risk” results:
Do not mean that the baby is abnormal. It only means that further invasive tests, such as amniocentesis or CVS, need to be considered to confirm whether the baby is normal or has Down's syndrome.

“Negative” OR “Low risk” results:
Only indicate that the risk that the baby has Down's syndrome as compared to that of pregnant women aged 35 is low. However, it does not completely eliminate the possibility that the foetus may have Down's syndrome or other chromosomal abnormalities. This test is not a test for intelligence or structural abnormalities.