Hydronephrosis is a medical condition characterized by a distention of the kidney caused by a buildup of urine which cannot be evacuated through the bladder. This condition can become quite dangerous, and it can also cause a variety of health problems, including long-term atrophy of the kidney as a result of the stretching caused by hydronephrosis. There are a number of causes for this condition, along with an assortment of treatment approaches.

Urine will back up into the kidneys if there is an obstruction in the urinary tract. This can be caused by a structural abnormality, compression of the urinary tract, or by movement of the kidney which causes a kink to develop, much like the kink in a hose. Obstructions such as tumors and kidney stones are also a common cause of hydronephrosis. Whatever the cause, urine will slowly start to pool in the kidney, eventually causing it to distend with the pressure of the fluid inside.

This condition can be characterized as unilateral, meaning that one kidney is involved, or bilateral, in which case both kidneys are affected. Bilateral hydronephrosis tends to cause more severe symptoms, which include decreased urination, pain, and tenderness in the abdomen. In extreme cases, the kidney may be so swollen that it is palpable on a physical examination.

In acute hydronephrosis, the blockage and swelling occur quickly, causing a rapid onset of symptoms. Chronic hydronephrosis takes longer to develop into a serious problem, and it can be caused by a partial blockage which simply slow drainage from the kidney, rather than bringing it to a halt. Both require medical attention so that the blockage can be identified and corrected.

Medical imaging such as ultrasound can often reveal a hydronephrosis situation, and the doctor may also use urine samples and bloodwork to test kidney function. Catheterization and more invasive procedures may be performed in an attempt to determine the cause and to clear the blockage. In some cases, surgery may be required to correct the problem which caused the hydronephrosis, while in other instances, it may be possible to remove the blockage with less invasive techniques.

If something like a tumor is causing the hydronephrosis, additional treatments may be needed to prevent recurrence. The kidneys may also need supportive therapy if the condition has been allowed to remain untreated for a prolonged period, with treatments like dialysis being used to give the kidneys a chance to recover.