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About Your Diagnosis

Hydronephrosis is defined as the distention or the expansion of the kidney resulting from a blockage preventing the urine from flowing out of the body. The blockage can occur anywhere along the urinary tract in men and women. Urine is the result of the kidney filtering the blood. As the blood passes through the kidney, tiny blood vessels called glomeruli act as filters of the blood. Urine is the filtered fluid crossing the glomeruli. The newly produced urine passes through small winding tubes in the kidney called convoluted tubules and collects in small ducts before it passes into the part of the kidney called the pelvis. From the pelvis, the urine flows into the urinary bladder through two long tubes called the ureters. Once inside the bladder, the urine must pass through the urethra. In men, the urethra is long and passes through the prostate gland and penis where the urine leaves the body. In women, the urethra is short (1 inches long) and opens just below the clitoris. Hydronephrosis can occur if there is a blockage along any part of the urinary tract.

In children, urinary tract obstruction is due to anatomic abnormalities such as narrowing or pinching (stricture) of the urethra and narrowing at the opening of the tubes passing into the bladder (ureters).

In adults, kidney stones, prostate enlargement, and prostate cancer are common causes leading to hydronephrosis. Other causes include cancers of the bladder, uterus, ovary, and colon, which can block the urinary tract and cause hydronephrosis.

Hydronephrosis can be cured, but this depends on the specific cause. Hydronephrosis can be detected by an ultrasound or by a computed tomography (CT) scan. In some cases a special radiograph (x-ray) called an intravenous pyelogram (IVP) can detect hydronephrosis.

Living With Your Diagnosis

Symptoms depend on the underlying cause. For example, in patients with kidney stones, the main complaint is blood in the urine along with severe flank pain that radiates into the groin. Patients with prostate cancer or an enlarged prostate will complain of difficulty urinating, nighttime urination, urgency, frequency, and incomplete emptying of the bladder. Patients with colon cancer may notice blood in the stools or change in bowel movements. Ovarian cancer, bladder cancer, and uterine cancer all have different modes of presentation (ask your physician for the Patient Teaching Guide about each specific disease).

Complications of urinary tract obstruction and hydronephrosis include urinary infections, hypertension, kidney failure, and dehydration.


Once the diagnosis of hydronephrosis is established, the treatment depends on the specific cause. If the obstruction is sudden, as can be seen in patients with enlarged prostate glands, a catheter is advanced through the urethra into the bladder to relieve the obstruction. This gives temporary and instant relief of the symptoms until more definitive therapy can be administered. Thereafter the decision about using medicines or having surgery to remove the prostate tissue can be made between you and your physician.

In patients with kidney stones, treatment will be guided by the physician and a urologist (a surgeon specializing in disease of the genital and urinary tract). Treatment can include pain control, hydration, and antibiotics along with either shock wave treatment, called lithotripsy, or surgery to remove the stone.

The goal of treatment is to relieve the obstruction. The prognosis that the kidney returns back to normal depends on how long the blockage has been there, if there are coexisting problems such as infections, stones, or hypertension, and how severe the obstruction is.

The DOs
  • Understand that hydronephrosis is not a disease but is the end result of many different diseases.
  • Realize that the longer the hydronephrosis remains untreated, the more kidney function is lost.
  • Seek advice from a urologist if hydronephrosis is detected.
The DON'Ts
  • Don't forget that hydronephrosis can occur in children as well as in adults.
  • Don't miss follow-up appointments with your physician. Depending on the cause of the hydronephrosis, your physician may recommend repeat ultrasounds to monitor the kidney size.
  • Don't be afraid to ask for second opinions or specialty consultation.
When to Call Your Doctor
  • If you have any abdominal pain or flank pain.
  • If you notice blood in the urine or stool.
  • If you notice a drop in your urine output.
  • If you cannot urinate.
  • If you have any urinary symptoms mentioned above.
For More Information
National Kidney Foundation
30 East 33rd Street
New York, NY 10016
American Cancer Society
1599 Clifton Road, N.E.
Atlanta, GA 30329


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