| Hydronephrosis | |
|---|---|
 | |
| Renal ultrasonography of hydronephrosis caused by a left ureteral stone | |
| Specialty | Urology, nephrology  |
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).