Now Scheduling Virtual Visits!
Yelp & Google Modal code


Hydronephrosis at a glance

  • Hydronephrosis describes when one or both kidneys become swollen from backed-up urine.
  • Hydronephrosis is fairly common, affecting 1 in 100 people.
  • Usually it is not serious, although it can have very serious effects in some people.
  • Several conditions of the urinary tract can cause hydronephrosis and physicians treat the underlying condition that causes hydronephrosis.

What is hydronephrosis?

Hydronephrosis is the condition of a kidney becoming swollen, caused when urine cannot drain from the kidney to the bladder, as it normally should.

Hydronephrosis can occur in one kidney (unilateral hydronephrosis) or both kidneys. It is not uncommon, occurring in 1 in 100 adults at some time in their lives. It also occurs fairly frequently in infants either before birth (prenatal hydronephrosis) or after (postnatal).

Causes of hydronephrosis

Hydronephrosis happens when there is an obstruction or blockage in the urinary system. The blockage can be in the kidney (which filters blood and converts waste to urine), the bladder (the organ that stores urine), or the ureter (the tube that transports urine from the kidney to the bladder). It also can occur when something happens to cause urine to flow backward from the bladder back into the kidney.

Hydronephrosis is not an illness in and of itself. Rather, it usually is a symptom of an illness or another underlying factor that causes hydronephrosis. Hydronephrosis can result from any of the following conditions:

Symptoms of hydronephrosis

Symptoms of hydronephrosis vary in severity depending on how long a person has had the condition. As fluid buildup increases, symptoms are likely to become more severe.

Initially, people might notice they are urinating more often. Some people also feel an increased urge to urinate.

The main symptom of hydronephrosis is pain in the side and back (called flank pain), as well as groin and/or abdomen pain.

Other symptoms may include:

  • UTI
  • Increased urge to urinate or increased frequency of urination
  • Pain during urination
  • Incomplete urination
  • Incontinence
  • Queasiness or vomiting
  • Abdominal mass (a lump and/or heaviness in the abdomen)
  • Fever.

Diagnosis of hydronephrosis

To diagnose hydronephrosis, a physician asks about a person’s symptoms and medical history. The doctor may feel (palpate) the patient’s back, side and abdomen and may be able to feel that the kidney is swollen.

Often hydronephrosis is diagnosed with an ultrasound test. This test uses sound waves to create an image of internal organs, such as the kidney. The ultrasound scan can tell the doctor whether the kidney is shaped unusually, whether obstructions are visible and whether unusual fluid is present.

If additional information is required, a doctor may order tests such as:

  • X-ray
  • Computed tomography (CT) scan of the abdomen and kidneys
  • Magnetic resonance imaging (MRI) scan of the abdomen
  • Cystoscopy (a lighted camera on a small tube, which allows a physician to see inside the bladder and the urethra)
  • Urinalysis and/or blood tests to check for kidney function
  • Tests for blood in urine, which can indicate a kidney stone or other issue
  • Isotope renography (kidney scan).

Treatment of hydronephrosis

The treatment for hydronephrosis will depend on what has caused the kidney swelling. Some cases are resolved fairly simply. For instance, a UTI may be treated with antibiotics. If a kidney stone or other urinary stone is causing a blockage, the kidney stone may pass by itself, or may require other removal to eliminate the blockage.

Other conditions might be more complex and may require additional treatment. These treatments may include:

  • Catheter drainage of excess urine: This procedure drains the bladder and can also give doctors a sense of whether there is a blockage in the bladder.
  • Insertion of a ureteral stent: The doctor may insert a tube that widens the ureter so that urine can drain into the bladder.
  • Placement of a nephrostomy tube: This allows urine to drain through the back, into a drainage bag.
  • Antibiotic treatment: This may be used to control infection and can be a long-term treatment to control repeated urinary tract infections.
  • Surgical treatment: Some obstructions, such as a blood clot, scar tissue or tumor, need to be removed with surgery. In some cases, the surgeon may remove the damaged portion of the ureter and then reconnect the healthy portion. This procedure can correct urine flow so that the urinary system works normally.

Anyone with signs of possible hydronephrosis should see a doctor. Untreated UTIs or other infections can cause more serious conditions, such as kidney infection (pyelonephritis) or systemic infection such as sepsis (blood poisoning).

It is especially important to seek treatment quickly if the person has only one kidney or such immune system disorders as HIV or diabetes. These individuals are at risk of requiring dialysis or a kidney transplant if hydronephrosis permanently damages the remaining kidney.