Left hydronephrosis accompanied by ureteral dilatation what is the meaning

Ureteral obstruction is usually caused by left hydronephrosis.

Normally, urine is discharged through the kidneys, then flows through the ureter and stored in the bladder. When it accumulates to a certain amount, it will be discharged from the urethra. However, when urine is not discharged properly due to various reasons, such as ureteral inflammation, stones or tumors, urine will accumulate at the proximal end of the lesion, resulting in ureteral dilatation. Over time, the accumulated urine gradually increases, which can further cause renal pelvis dilatation and form hydronephrosis.