You could do something like:

DECLARE @operation as Varchar(10);

DECLARE @Count as int;

SET @operation = 'Inserted';

SELECT @Count = COUNT(*) FROM DELETED;

if @Count > 0

BEGIN

SET @operation = 'Deleted';

SELECT @Count = COUNT(*) FROM INSERTED;

IF @Count > 0

SET @operation = 'Updated'

END

HTH,

Rob