Hi Frederic,
As a general rule, it is difficult to say that a problem or disease is “specific” to a particular channel. As Armin suggested, it very much depends on the context, namely, signs and symptoms associated, anamnesis data, case history, information gathered by pulses and tongue observation and the overall energetic situation of the patient. There should be other “reasons” to go for one channel treatment or another. Sometimes you might feel that the work does not really start with a channel that relates directly to the issue at stake and that you have to work on other superficial layers before addressing the main concern directly. The possibilities are limitless.
Having said that, if you decide to go for a Bladder Divergent treatment, it might be a good idea to do guasha insisting in the area of Huatojiaji points to release the tension built-up over the years, if that is to be found.