Talk to Nephrologist on Shrinkage In Left Kidney

Aslam alikum.. I hope you are doing well. Sir I want to ask about my cousin. He is 13 years old. He is facing some kidney problem. His left kidney vein is shrinked due to which he was facing difficulty in urine. When we know his disease doctors said that he have this problem since he was born. some doctors recommed operation while some other not. They said his age is less.. During operation may be some other problems may rise . the worst problem is now his second kidney get swallowed and sometimes he get severe fever also. what do you recommend. please let me know if you can help Thanks