Which condition can lead to hydronephrosis if not addressed?

Hydronephrosis, which is the dilation of the renal pelvis and calyces due to urine buildup, can occur when there is an obstruction in the urinary tract. Ureteral stricture refers to a narrowing of the ureter, which can impede the normal flow of urine from the kidney to the bladder. If urine cannot pass through the stricture, it backs up into the kidney, leading to hydronephrosis.

In contrast, chronic renal failure does not directly cause hydronephrosis but rather leads to a gradual decline in kidney function rather than obstruction. Polyuria, which is characterized by excessive urine production, generally does not lead to hydronephrosis as it doesn't produce an obstruction—rather, it might indicate an underlying condition affecting urine concentration. Mild dehydration, while it may lead to concentrated urine, is not typically associated with obstruction and therefore does not cause hydronephrosis.

Thus, the condition that is relevant to the development of hydronephrosis through obstruction is ureteral stricture, making it the correct choice in this context.