Definition Hydronephrosis of the Kidney

Hydronephrosis of the KidneyHydronephrosis of the Kidney – a circumstance in which the renal pelvis, the portion of the kidney that collects urine for passage from the kidney via the ureter, dilates and enlarges.

Hydronephrosis results from conditions of the kidney that slow or block the flow of urine, causing urine to back up into or pool in the renal pelvis.

Such conditions may include obstructive nephrolithiasis (kidney stones that block the ureter), neurogenic bladder (in which the bladder fails to respond to the normal neurosensory signals that regulate urination and becomes overly full), and Vesicoureteral Reflux (urine washes back into the ureters from the bladder).

Unilateral hydronephrosis, which affects only one kidney, is the more common presentation. Bilateral hydronephrosis, which affects both kidneys, often indicates congenital anomaly of kidney or ureteral structure though may develop as a consequence of conditions such as hypertension (high blood pressure), diabetes and benign prostatic hyperplasia (bph) that constricts the urethra and slows the flow of urine during urination.


The symptoms of hydronephrosis may include

  • abdominal or back pain
  • dysuria (discomfort or burning with urination)
  • urinary frequency
  • urinary urgency
  • signs of infection such as fever and cloudy or bloody urine

Diagnosis and Treatment

Some people may have no symptoms, with the hydronephrosis showing up during evaluation of other medical concerns or in pregnancy. The diagnostic path begins with urinalysis and blood tests to evaluate kidney function and usually includes an abdominal X-Ray, ultrasound, computed tomography (ct) scan, intravenous pyelogram (ivp), or magnetic resonance imaging (mri) examination to visualize the kidneys.

Treatment targets the underlying disease process to restore the free flow of urine. Untreated hydronephrosis results in permanent damage to the kidney that may lead to renal failure.

See also hematuriahorseshoe kidney; nephritis; nocturiaurinary tract infection (uti).

How did you like this article?

Page last reviewed:

About Us