A pregnant female, 38 years old, had a child with Down's syndrome. How do you assess the risk of Down's syndrome in the present pregnancy:
Material alpha-feto protein
Material HCG
USG
Chorionic villous biopsy
In patients with previous history of Down syndrome
“The risk of recurrence is greater than the risk of genetic diagnosis and these patients should be advised to seek genetic counselling and to have a genetic diagnosis.”
Fernando Arias 3/e, p 27
Therefore amniocentesis /Chorionic villous biopsy should be done.