“There is atelectasis present at the lung bases.”

How bad is the atelectasis? Is it something to worry about?

This report is just a radiologist thinking out loud.  Saying something like “mild dependent atelectasis” at least gives the  idea that it’s an insignificant finding. (I may argue an insignificant finding shouldn’t be mentioned.)

If there is “significant” atelectasis, describe the degree as subsegmental, segmental, lobar etc., and try to identify the cause (passive, compressive, obstructive, cicatricial).