stricture and supra pubic catheter

[chuffen]

My uncle, who is 81 and living in England, developed a urethral stricture approximately one year ago.  The U.K. doctors could not pass a catheter into the urethra, so they decided to put a supra pubic catheter in place.  Surgery was deemed inappropriate, for reasons that were never shared with my uncle or me.  

Over the last year, the catheter has been being replaced every eight to ten weeks.  He has a valve that he opens when he feels the need to urinate, and he drains this valve into a toilet.  He prefers not to carry around a leg bag, as he is quite active as a scholar, attending academic conferences on the Continent, etc.  

The problem is this: he experiences a great deal of pain as his bladder fills, and when he opens the valve, the pain becomes very severe.  It diminishes as the bladder empties.  The doctors have tested his urine several times for infection, and declare he is infection free.  

Meanwhile, he has developed a bad, itching skin rash (distant from the catheter site), as well as thick, discolored, elephant like skin on his legs below the knees.  The doctors are treating these conditions with benadryl and with topical cremes.  It's not clear whether these skin conditions are related to the catheter or the pain, but they are treating them as if they were separate medical problems.

From my vantage in the U.S., I think that some kind of reconstructive surgery would be better than a permanent catheter, but the National Health doctors disagree.  So, the catheter remains.  Is there any explanation of why it should be so painful?

Thank you for your help with this.