What does left renal calyceal hydronephrosis mean?

Calyceal hydronephrosis is also called hydronephrosis, because obstruction of the urinary system causes the renal pelvis and calyces to dilate and then retain urine. It is collectively called hydronephrosis because the accumulation of urine in the kidneys increases the pressure, causing the renal pelvis and kidneys to enlarge and the renal parenchyma to shrink. Therefore, it shows the condition of hydronephrosis, which can be divided into congenital and acquired causes of congenital obstruction, mainly including staged non-function, intrinsic ureteral stricture, ureteral torsion, adhesion, vascular compression, high ureteral opening, etc. Acquired obstruction is mainly due to inflammation or ischemic scars leading to local fixation, vesico-ureteral reflux leading to ureteral distortion, coupled with periureteral fibrosis, as well as renal pelvis and ureteral tumor polyps leading to obstruction.