Hi, The most common delayed complication is restenosis during followup, although only some develops that. You need not worry about transplantation now- he had undergone surgery without delay, relieving obstruction and hence allowing kidneys to function normally. Just keep him under regular followup so as to detect any stenosis without delay. Also report to doctor if he develops fever & crying on micturition, suggesting urine infection that needs early treatment with antibiotics. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Muhammed Aslam TK, Pediatrician