A distention of the renal pelvis due to urine collecting in the kidney is

The correct answer is hydronephrosis. Distention means being enlarged or swollen due to internal pressure. In this case, the internal pressure would be urine collecting in the kidney. This occurs when the urine is unable to drain from the kidney to the bladder due to an obstruction. Contrary to common belief, hydronephrosis is not a disease itself, but is instead is the result of a disease.