My understanding is that a DNA test will tell you exactly whether or not a child has CAH and what type.  Neither my husband nor myself ever had the DNA testing done, even though our first 2 children were born with SWCAH.  My first born was diagnosed through a newborn screen-he was a full term baby.  My second child was diagnosed in utero at 16 weeks gestation via an amniocentesis and she too was diagnosed as SWCAH.  My third child was also tested in utero via an amnio and tested negative, and after he was born I insisted on another DNA test to rule it out.  I was told DNA testing is the most definite and accurate way to determine if a child is CAH and which type because they can look at the mutations if any exist.

Another thing I was told at one point by my genetic counselor is that a child can be born with CAH even if neither parent is a carrier.  She called this a spontaneous mutation, meaning the newborn child is the first  on either side of the family tree  to exhibit the mutation. 

Anyway, hope this helps.  My bet would be on the DNA testing as soon as baby Ryan is ready.  But I agree that it would be better in this situation to medicate and then find out he does not have it, than to NOT medicate and risk him having a crisis if he does have it.  Best wishes and best of luck.

Nicole