Understanding hydronephrosis

When a person has swelling of a kidney due to a build-up of urine this is known as hydronephrosis. This condition which can affect one or both kidneys and can happen at any age is when urine is unable to drain from the kidneys.  Generally this occurs from a blockage in the tubes (ureters) that drain urine from the kidneys.  An anatomical defect is another possibility preventing urine to drain properly.

Symptoms of hydronephrosis

Not everyone who develops hydronephrosis will have symptoms but when they do occur, here are some possible signs of it:

·      Pain in the side and back (flank pain) that may travel to the lower abdomen or groin

·      Urinary problems, such as pain with urination or feeling an urgent or frequent need to urinate

·      Nausea and vomiting

·      Fever

·      Failure to thrive seen in infants who have hydronephrosis

Causes of hydronephrosis

In a normal functioning kidney, the urinary tract’s job is to remove wastes and fluid from the body.  There are four parts to the urinary tract: the kidneys, the ureters, the bladder, and the urethra. Urine is formed when the kidneys filter blood and remove excess waste materials and fluid. As urine is made, it travels down a narrow tube called the ureter into the bladder.  Overtime, the bladder slowly fills up with urine, which empties from the body through another small tube called the urethra. Hydronephrosis occurs when there is either a blockage or of the outflow of urine or reverse flow of urine already in the bladder causing the renal pelvis to become enlarged.

A couple of common causes of hydronephrosis include:

·      Partial blockage in the urinary tract – Urinary tract blockages form where the kidney meets the ureter, at a point called the uerteropelvic junction. Blockages may also occur where the ureter meets the bladder at what’s called the uretervesical junction.

·      Vesicoureteral reflux – This happens when urine flows backward through the ureter from the bladder up into the kidney. Normally, urine flows only one way in the ureter. Urine flowing the wrong way makes it difficult for the kidney to empty properly and causes the kidney to swell.

Other possible but less common causes of hydronephrosis could be kidney stones, a tumor in the abdomen or pelvis, and problems with nerves that lead to the bladder.

Diagnosing hydronephrosis

Anyone who is experiencing signs of hydronephrosis needs to be evaluated by their doctor.  To determine if person has this condition, the following tests may be done:

·      A blood test to evaluate kidney function

·      A urine test checking for signs of infection or urinary stones that could cause a blockage

·      An ultrasound imaging exam to allow the doctor to view the kidneys, bladder, and other urinary structures to identify potential problems

·      A voiding cystourethrogram.  This is an X-ray exam using special dye to outline the kidneys, ureters, bladder, and urethra, capturing views both before and after urination.

Hydronephrosis treatment

Treatment will be based on the underlying cause of hydronephrosis. Occasionally surgery is necessary but hydronephrosis can also resolve on its own. If a person has a mild to moderate case of hydronephrosis, either a wait-and-see approach may be taken and or preventive antibiotic therapy may be given to lower the risk of a urinary tract infection.  In more severe cases of hydronephrosis, then surgery will be done to remove the blockage or fix the reflux. 

To not treat hydronephrosis runs the risk of permanent kidney damage if it is severe. Kidney failure rarely occurs and in most cases, the condition resolves successfully.