First off a huge congratulations on your pregnancy!

I too am 27 weeks pregnant with my second set of twins.  We opted for an amnio and also had the FISH results in which we learned that we are having a boy and a girl.  I had my amnio at 16 weeks and at 18 weeks I had all the results.  The chromosone results came back within the week.  The CAH results however came back one week later.  Since Cornell likes to grow the cultures an extra three days in their lab, we didn’t find out until exactly forteen days after the amnio. 

This is why I don’t understand why your CAH results are taking twenty days to receive.  Is it because you did a CVS and the culture is different? 

Hoping your having a wonderful and healthy pregnancy, and don’t forget to keep us updated on your progress!