Hydronephrosis is mostly caused by obstructive diseases of the upper urinary tract. Common diseases include upper urinary tract stones, tumors of the urinary system, congenital stricture of the ureteropelvic junction, ureter behind the vena cava, ureterocele, urinary tuberculosis, scar stenosis caused by trauma or inflammation, central or peripheral neuropathy, etc. In addition, when the adjacent organ diseases oppress or invade the ureter, it will also cause hydronephrosis, such as colon cancer, pelvic tumor, retroperitoneal fibrosis and other diseases. Long term obstructive diseases of the lower urinary tract can also lead to hydronephrosis, such as benign prostatic hyperplasia, neurogenic bladder and other diseases. If the obstruction is not relieved in time, long-term hydronephrosis, increased intrarenal pressure, atrophy of renal parenchyma, and dysfunction will cause renal failure on the hydronephrosis side.
