Pyonephrosis vs. Hydronephrosis — What's the Difference?

Pyonephrosis (Greek pyon "pus" + nephros "kidney") is an infection of the kidneys' collecting system. Pus collects in the renal pelvis and causes distension of the kidney.

Hydronephrosis describes hydrostatic dilation of the renal pelvis and calyces as a result of obstruction to urine flow downstream. Alternatively, hydroureter describes the dilation of the ureter, and hydronephroureter describes the dilation of the entire upper urinary tract (both the renal pelvicalyceal system and the ureter).

An infection of the renal collecting system, in which pus collects in the renal pelvis and causes distension of the kidney.

The dilation of the pelvis and calyces of one or both kidneys because of the accumulation of urine resulting from obstruction of urine outflow.

(pathology) distension of the kidneys due to obstruction in the flow of urine

An accumulation of urine in the pelvis of the kidney, occasioned by obstruction in the urinary passages.

Accumulation of urine in the kidney because of an obstruction in the ureter