Hydronephrosis (swelling of the kidneys)

Hydronephrosis (swelling of the kidneys)

Hydronephrosis is the swelling of a kidney due to expansion caused by accumulation of urine. It happens either when there is a blockage (obstruction), reflux of urine upwards from the bladder or residual swelling which still persists after the obstruction has been removed.

Hydronephrosis can occur in one or both kidneys.

Hydronephrosis may or may not cause symptoms. The symptoms will depend on the cause. You may have pain, either in the side and back (known as flank pain), abdomen or groin, depending on the cause.

Other symptoms may include pain during urination, other problems with urination (increased urge or frequency, incomplete urination, incontinence), nausea and fever. These symptoms depend on the cause and severity of urinary blockage.



Hydronephrosis is usually caused by another underlying illness or risk factor. Causes of hydronephrosis include, but are not limited to, the following illnesses or risk factors:

  • Urinary stones blocking the outflow from the kidney
  • Congenital blockage (a defect that is present at birth)
  • Blood clot
  • Fungal ball
  • Scarring of tissue (from injury or previous surgery)
  • Tumor or cancer (bladder, cervical, colon, pelvic or prostate cancer)
  • Enlarged prostate (noncancerous)
  • Pregnancy


Hydronephrosis is usually confirmed with ultrasound.

Confirmation of the diagnosis of the underlying cause may be required with x-rays, computerized tomography (CT) and magnetic resonance imaging (MRI).

Diagnosis may also require cystoscopy with retrograde endourological procedures, which uses a long tube with a light and camera at the end (cystoscope) that allows the doctor to look inside the bladder and urethra, and the ureter.

Blood and urine tests may also be required to check the kidney function.



Treatment of hydronephrosis is the treatment of the underlying disease or cause, such as a kidney stone, tumor or infection.

If a blocked ureter is causing your condition, your doctor might need to do any of the following:

  • insert a ureteral stent, which is a tube that allows the ureter to drain into the bladder
  • insert a nephrostomy tube, which allows the blocked urine to drain through the back
  • prescribe antibiotics to control infection

Your doctor might have to remove the obstruction with surgery. If something like scar tissue or a blood clot is causing the blockage, your doctor might remove the affected area completely. They can then reconnect the healthy ends of your ureter to restore normal urine flow.

If the cause of your hydronephrosis is a kidney stone, you may need surgery to remove it. To do this, your doctor might perform endoscopic surgery, which involves using tiny instruments to perform the procedure. This drastically reduces your healing and recovery time.

Your doctor might also prescribe you antibiotics. This will help ensure you don’t develop a kidney infection.

In cases of severe blockage and hydronephrosis, excess urine may need to be removed using either a catheter to drain urine from the bladder or a special tube called a nephrostomy that drains urine from the kidney. Treatment need to be done as soon as possible in order to avoid any permanent damage to the kidneys.

Infected obstruction with hydronephrosis is a urological emergency and should be dealt with the earliest possible.

Severe cases of urinary blockage and hydronephrosis can damage the kidneys and lead to kidney failure. If kidney failure occurs, treatment will be needed with either dialysis or a kidney transplant. However, most people can recover from hydronephrosis if treated early and promptly.