Hydronephrosisis a condition linkedwith impaired urine outflow. It is usually well-treatable but without adequate therapy it may cause serious complications including life-long impairment of kidney function. In normal situation, blood fluid is filtered in kidney (pair abdominal organ) into renal pelvis, which is a funnel-shaped tissue in contact with kidney tissue. Out of the pelvis, the urine flows through ureter into the urinary bladder and then through urethra out of the body.


If the outflow of urine is for any reason disrupted, the urine accumulates and may return back to ureter towards the pelvis and the kidney and damage the kidney tissue by locally elevated pressure. One or both kidneys may be affected; it depends on the location of obstruction. The most common cause is a urinary stone blocking the ureter. Less commonly, the problem can happen in ureter cancer, bladder cancer, strictures of urethra, enlarged prostate and prostate cancer. In childhood, hydronephrosis may occur in untreated severe forms of so-called vesicoureteral reflux (VUR).


Schema -
hydronephrosis while ureter is closed by urinary stone



Unilateral hydronephrosis may be no visibly symptomatic. The urine accumulation, however, increases risk of urinary tract infections including kidney infection. If the obstruction is caused by a urinary stone, the patient usually suffers from renal colic pain. Prolonged pressure of the fluid on renal tissue may result in complete loss of its function. If there is bilateral hydronephrosis, the patient may begin to suffer from symptoms of acute kidney failure. Therefore, bilateral hydronephrosis is more dangerous, but on the other hand more easily to diagnose as the patient does not urinate. When only one kidney is affected, the patient urinates seemingly normally as the urine flows out of the healthy kidney.


The best diagnostic measure is ultrasound of the abdomen that confirms not only the hydronephrosis with dilated kidney pelvis, but it can also evaluate the degree of damage done to the kidney according to the width of compressed kidney tissue. Urinary stones can be sometimes visualized by the ultrasound or by simple abdominal X-ray. The urologists usually perform a cystoscopy by using an endoscopic tubular device to check the urinary tract and eventually eliminate the obstruction.


Hydronephrosis should be dealt with by urologists, who try to remove the obstacle and ensure correct urinary outflow. Problems with urethra (usually caused by enlarged prostate) may be solved by catheterization, urinary stones may be removed endoscopically and ureters unstopped by special tubular stents (hollow tube-like devices). If it is not possible to solve the situation, it is possible to put a thick needle into the renal pelvis to allow the urine to flow away and ensure the drainage (so-called nehprostomy).


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Contact: jiri.stefanek@seznam.cz
 Sources: basic text sources