What Causes Hydronephrosis?
Hydronephrosis is not a disease in and of itself. Instead, it can be caused by a number of internal and external conditions that affect the kidney and the kidney urinary collecting system.
One of the most common causes is a condition is called acute unilateral obstructive uropathy. This is a sudden development of an obstacle in one of your ureters (the tubes that connect your kidneys to your bladder). The most common cause for this blockage is a kidney stone, but scarring and blood clots can also cause acute unilateral obstructive uropathy. A blocked ureter can cause urine to go back up into the kidney, which causes swelling. This backflow of urine is called vesicoureteric reflux.