The so-called hydronephrosis often occurs due to some factor blocking the urinary system, causing urine to not be excreted normally. The most common cause is urinary system stones, but it can also be due to issues like tumors or benign prostatic hyperplasia.

The treatment for stones depends on the size of the stone. Stones smaller than 5 millimeters in diameter can often pass naturally. If the stone is 7 to 15 millimeters in diameter, extracorporeal shock wave lithotripsy is typically used. If stones in the lower mid-ureter do not respond well to medication, retrograde removal under cystoscopy can also be performed.

For some patients who have had a long-standing obstruction, renal function may already be impaired. If the obstruction cannot be relieved, surgeries such as creating a urinary diversion can be performed. This includes procedures like bladder fistulation, pyelostomy, or percutaneous ureterostomy, among others.