Hydronephrosis is a condition that typically occurs when one kidney becomes swollen due to the failure of normal drainage of urine from the kid...

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What is Hydronephrosis?

Hydronephrosis is a condition that typically occurs when one kidney becomes swollen due to the failure of normal drainage of urine from the kidney to the bladder. This swelling most commonly affects only one kidney, but both can be involved. Hydronephrosis is not a disease but a structural condition. It is a result of a blockage of or obstruction in the urinary tract. While this condition occurs in about 1 in 100 adults, it’s also fairly common in babies. According to the Boston Children’s Hospital, hydronephrosis affects about one in every 500 people (BHC).

What Causes Hydronephrosis?

Hydronephrosis is not a disease in and of itself. Instead, it can be caused by a number of internal and external conditions that affect the kidney and the kidney urinary collecting system.

One of the most common causes is a condition is called acute unilateral obstructive uropathy. This is a sudden development of an obstacle in one of your ureters (the tubes that connect your kidneys to your bladder). The most common cause for this blockage is a kidney stone, but scarring and blood clots can also cause acute unilateral obstructive uropathy. A blocked ureter can cause urine to go back up into the kidney, which causes swelling. This backflow of urine is called vesicoureteric reflux.

Other causes of blockage may include:

  • a kink in the urteropelvic junction (where the ureter meets the pelvis of the kidney)
  • tumors in or near the ureter
  • narrowing of the ureter from an injury or birth defect

What Are the Symptoms?

In the normal human body, urine flows through the urinary tract with minimal pressure. If there is an obstruction in the urinary tract, pressure can build up. Once urine has built up for an extended period of time, your kidney can start to become enlarged. Your kidney may become so engorged with urine that it starts to press on nearby organs. If left untreated for too long this pressure can cause your kidneys to lose function permanently.

The symptoms you have depend on how long you’ve had the obstruction. If you have hydronephrosis you could have mild symptoms like urinating more frequently and an increase in the urge to urinate. Other potentially severe symptoms you may experience are:

  • pain in the abdomen or flank
  • nausea and vomiting
  • pain when urinating
  • frequency of urination
  • urgency of urination
  • urinary tract infection (UTI)
  • fever

When the flow of urine is interrupted, your chances of getting a urinary tract infection (UTI) increase. This is why UTIs are one of the most common symptoms of hydronephrosis. Some signs of a UTI include:

  • cloudy urine
  • painful urination
  • weak urine stream
  • back pain
  • fever

If you see signs of hydronephrosis, schedule an appointment with your doctor to talk about the symptoms you’re experiencing. It is important to remember that untreated UTIs may lead to more serious conditions such as pyelonephritis (infection of the kidney) and sepsis (infection in the bloodstream or blood poisoning).

Diagnoses of Hydronephrosis

Making sure that you’re diagnosed as early as possible is extremely important. If your condition is left untreated for too long your kidneys could be permanently damaged. Your doctor will likely begin his or her questioning by getting an overall assessment of your health status and then focus on any urinary symptoms you might have. On physical examination, your doctor may be able to feel your enlarged kidney by palpating the abdomen and flank area.

Your doctor may use a catheter to drain some of the urine from your bladder. If he or she is able to release a large amount of urine in this way it could mean that your obstruction is in your bladder or your urethra. The urethra is a tube that carries urine from your bladder to the outside of your body. Your doctor may also want to perform an ultrasound or computed tomography (CT) scan to have a closer look at the extent of the swelling and to possibly locate the area of the blockage. Both of these procedures let your doctor view an image of the inside of your body.

Treatment Options for Hydronephrosis

Treatment for hydronephrosis is primarily focused on getting rid of whatever is obstructing the flow of urine. The treatment option your doctor chooses for you will depend on the cause of your obstruction.

If your condition is caused by a blocked ureter, the following procedures might be performed:

  • Insertion of a ureteral stent (tube that allows the ureter to drain into the bladder)
  • Insertion of a nephrostomy tube (allows the blocked urine to drain through the back)
  • Antibiotics to control infection

It is possible that the doctor could remove the obstruction with surgery. If the blockage is caused by something like scar tissue or a blood clot, the affected area may be removed completely. Your surgeon can then reconnect the healthy ends of your ureter to restore normal urine flow.

If the cause of your hydronephrosis is a kidney stone, surgery may be needed to remove it. Your kidney stone might be removed with endoscopic surgery, which uses tiny instruments to perform the procedure. This allows your doctor to make smaller incisions, drastically reducing your healing and recovery time. Your doctor might prescribe you a trial of low-dose of antibiotics. This will help ensure you don’t develop a kidney infection.

Written by: Carmella Wint
Edited by:
Medically Reviewed by: Brenda B. Spriggs, MD, MPH, FACP
Published: Aug 7, 2012
Published By: Healthline Networks, Inc.
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