Sorry, I feel really dumb here, but what is the ct and BAL?
My kids didnt really have any invasive tests at all, and I think it depends on your clinic how they structure things. Some clinics do bronchoscopies as a matter of course, but my kids have never had them done, and personally I probably wouldnt allow it without a good reason.
On the other hand, other parents will tell you that a bronch picked up pseudomonas before it was evident, and preventative treatment was given sooner raather then later.