Even after 5 yrs, he can have strictures at the anal opening leading to the pouch entrance. Hence, if strictures present (which is scar tissue, narrowing of anal opening, dilation may be advised to "breakup" that scar tissue/ strictures", and dilation at the GI's office? It may be enuf to help improve him emptying/ voiding his pouch quicker. Questions to ask ur GI? (I regularly have to have this done.)
Good luck!