What is Hydronephrosis?


Hydronephrosis is a urinary tract defect, which involves swelling of one or both kidneys. This occurs when urine cannot flow out of the kidneys, due to blockage somewhere in the urinary tract.

The blockage that causes hydronephrosis is usually caused by a flap of tissue near to the posterior urethral valves (where urine empties from the bladder). Other causes may include kidney stones, enlarged prostate gland and pregnancy.  These can all cause blockage and obstruction of the flow of urine, causing urine to back up in the kidneys.  As a consequence, urinary tract infection (UTI) is usually associated with hydronephrosis.

Symptoms of Hydronephrosis

Symptoms may include:


  • Pain in the back, flank and/ or groin area;

  • Blood in the Urine;

  • Burning urine;

  • Cloudy urine;

  • Fever and general discomfort.


Treatment involves relieving the obstruction or correcting the defect that might be causing urine to back up in the kidneys.  The use of stents or catheters may be required and, if there is infection, antibiotics may be prescribed.  While many mild cases of hydronephrosis are resolved without surgery, severe cases of this kidney disease require surgical intervention. In severe cases, some kidney damage may remain.