How accurate is triple afp test for down syndrome?

About 70 percent: Triple screening test which includes AFP (alfa feto protein) level detects approximately 70 percent of fetuses affected by down syndrome.

Not very.: The triple screen will detect about 70% of mothers carrying babies with down syndrome, but it is only a screening test and does not diagnose down syndrome. There are many false positive tests ("abnormal" tests in women who are carrying babies that do not have down syndrome). A newer blood test for fetal dna in the mother's blood can actually diagnose Down syndrome in women who are at higher risk.