OSCAR stands for "One-Stop
Clinic for Assessment of
Risk". This is the latest prenatal screening program for Down's Syndrome, introduced
from Fetal Medicine
Foundation of United Kingom. The screening program is performed during 11-13 (+6d)
weeks of gestation, and consists of the measurements of
Nuchal Translucency, maternal serum level of
Pregnancy Associated Plasma Protein-A (PAPP-A), and free beta-human Chorionic
Gonadotropin (free beta-hCG). The chance of having a Down fetus is computed
using the above information. This screening test is safe with a detection rate
- Firstly, ultrasound scanning is performed to confirm the gestational age
and fetal size. The nuchal translucency is also measured.
- Blood is then taken from the pregnant woman for PAPP-A and free-beta hCG
assay. The result will be available after an hour.
- A software issued by
Foundation will be used to compute the chance of Down's syndrome. The test
is regarded as positive if the computed chance is higher than 1:180 for T21,
1:150 for T13 & T18; otherwise
it is negative.
- About 7% of all women undergoing the screening will have a positive result
(high risk). Further invasive procedures such as chorionic
villus sampling or amniocentesis will be
required to confirm whether the fetus is having Down's syndrome. We recommend chorionic villus
sampling as it can be performed before 14 weeks, and have the same risk of
amniocentesis (1% abortion rate).
- A negative screening test indicate that the chance of having a Down fetus
is very low, though it cannot be totally excluded. Invasive procedures
are not indicated.
Comparing OSCAR and other screening programs
Currently in most of the public and private obstetrtic sectors in Hong Kong,
Down's Syndrome is screened by maternal age or second trimester biochemical
tests (maternal serum levels of alpha-fetal protein and total hCG). The
detection rate is only 30% and 70% respectively. Moreover, the
biochemical screening cannot be performed until after 16 weeks. Result can only
be available few days later. On the other hand, OSCAR can be done before 14
weeks, and the result can be generated in an hour. Its detection rate is the
highest among all. The detail scientific report of OSCAR can be viewed from
How can I join OSCAR?
You can contact us by phone 2632-6412 /2632-4219 or make an appointment via