Hydronephrosis is a condition in which your urine (pee) can't drain from the kidney to the bladder due to a blockage or obstruction. Often, the obstruction causes kidney swelling, which may affect one or both kidneys.
If left untreated, hydronephrosis can lead to decreased kidney function and possible permanent kidney damage.
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Hydronephrosis occurs when a kidney swells and can't drain urine (pee) to the bladder as it normally does. This swelling is usually from a blockage or obstruction.
Over time, if left untreated, the backup of urine can affect kidney function and even cause permanent kidney damage in extreme cases.
Hydronephrosis usually affects only one kidney but may involve both.
Hydronephrosis affects about 1% of babies and 1% of adults.
Hydronephrosis isn't a primary disease. It's considered a secondary condition because it results from an underlying structural condition. Its cause can be internal and external conditions that affect the kidney and the urinary collecting system (UCS).
A common cause of hydronephrosis is acute unilateral obstructive uropathy, the sudden onset of an obstruction in one of the ureters — the tubes that connect your kidneys to your bladder. Kidney stones commonly cause this blockage, but scar tissue and blood clots can also cause it.
A ureter blockage may cause urine to backflow into the kidney, causing swelling. This condition is known as vesicoureteral reflux (VUR).
Additional causes of an obstruction include:
You may be at risk of hydronephrosis if you have certain underlying conditions.
These conditions may include:
A urinary tract infection (UTI) is the most common complication of hydronephrosis.
Signs of a UTI include:
If you have signs of a UTI, schedule an appointment with your doctor to talk about your symptoms.
If you don't treat a UTI, it can lead to more serious conditions, including:
In the urinary tract, urine normally flows through with little pressure. But if a ureter is blocked, urine can build up pressure and cause the kidney to enlarge. The engorged kidney may become so large that it presses on other organs.
At first, hydronephrosis may cause only mild symptoms like:
Other potentially severe symptoms are:
Your doctor will take your medical history and do a physical exam, but they'll need to order tests to diagnose hydronephrosis.
Tests used to diagnose hydronephrosis include:
It’s important to get treatment as soon as possible to avoid any permanent damage to the kidneys. Severe hydronephrosis can lead to kidney failure, which may then require dialysis or a kidney transplant.
Most people recover from hydronephrosis with prompt treatment.
The key goal of treatment for hydronephrosis is to prevent any further swelling of the kidney.
Common treatment options include:
In severe cases of hydronephrosis due to a blockage, extra urine may need to be drained using either a catheter or a special tube called a nephrostomy.
Last reviewed by a UPMC medical professional on 2024-09-05.
