Separation of the renal collecting system above 0.7cm is significant, and the diagnosis can be confirmed if it exceeds 1cm. The renal collecting system mainly refers to the renal calyx and renal pelvis, which cannot be completely distinguished in ultrasound, and are a lumpy area collectively referred to as the renal collecting system. Separation of the renal collecting system suggests hydronephrosis of the right kidney, and there is also the possibility of a tumor. Long-term renal collecting system separation will lead to thinning of renal cortex, renal function decline, and finally develop into chronic renal failure or even uremia. Therefore, clinically, the separation of the collecting system is generally regarded as more than 0.7cm as clinically significant, and more than 1cm is of greater clinical significance. With the separation of the collecting system, we must actively search for the causes, such as urinary stones, tumors, prostate hyperplasia, or renal pelvis, ureteral junction stenosis, etc., and then do the next step according to the cause.