A dilated renal pelvis usually indicates the presence of hydronephrosis. In the case of hydronephrosis, the main cause is the presence of urinary tract obstruction. Common causes of hydronephrosis include ureteral stenosis, ureteral calculi, prostatic hyperplasia, etc. Generally, if the hydronephrosis is unilateral, the obstruction should be removed in time, for example, for hydronephrosis caused by ureteral stenosis, end-to-end ureteral stenosis anastomosis can be performed. For hydronephrosis caused by ureteral stones, surgery is usually needed to remove the stones and relieve the obstruction in order to relieve the hydronephrosis. For prostatic hyperplasia, it often causes vesicoureteral reflux, resulting in bilateral dilatation of the renal pelvis, or bilateral hydronephrosis. In this case, transurethral resection of the prostate gland is usually required to remove the obstruction and allow unobstructed urination in order to relieve the hydronephrosis.