Question

Maternal serum screens claim to have a false positive rate of only 5%. This seems confusing, since the vast majority of women who score positive are not actually carrying a baby with Down’s Syndrome. Explain this apparent contradiction.

Answer 1

Maternal serum screens claim to have a false positive rate of only 5%. This seems confusing, since the vast majority of women who score positive are not actually carrying a baby with Down’s Syndrome. Explain this apparent contradiction.

Even with a false positive rate of only 5%, it has been observed that a vast majority of women are found to be positive about these women do not carry a child having Down’s syndrome. This is because these tests screen positive only for the trusting at chromosome number 18. Only when these tests are combined with the screen for Down syndrome, the baby would be actually carrying Down’s syndrome. Or else, when only trisomy 18 is checked, there is a huge chance that the baby might not turn out to be carrying down’s syndrome.