Hello, A dilated renal pelvis due to Ureteropelvic junction obstruction is called hydronephrosis or pelvicaliectasis. The blockage may be due to anatomic reason, such as a blood vessel to the kidney crossing over the top of the ureter at the ureteropelvic junction, or it may be due to a narrowed and nonfunctioning segment of the ureter. The definitive treatment is surgery and there are several surgical options based on the kind of obstruction. You should talk to your surgeon who will assess the obstruction before deciding the kind of surgery. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Prabhash Verma, General & Family Physician