[indian]

Often asked in USMLE is the triple test which is an maternal serum analysis carried at around the second trimester to screen for chromosomal abnormalities in the fetus.
It's called triple because it measures the following:

• Alfa Feto Protein
• Estriol
• beta hCG

You have to know how to interpret the results

in Edward Syndrome all levels are low
in Down Syndrome AFP and Estriol are low but bet hCG is high

 

[indian]

Most US states have added a fourth test to the panel which is inhibin A
It's no longer called the triple screen, it's now called Quad Screen