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Hydronephrosis / Obstruction

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Hydronephrosis is a condition in which there is swelling in the urine-collecting structures of one or both kidneys. This swelling is a result of an obstruction of urine flow from the kidney. This can result in the impairment of normal kidney functions and should be addressed immediately. Treatment will depend on the cause and severity of the obstruction.


  • Flank pain
  • Abdominal mass
  • Nausea and vomiting
  • Urinary tract infection
  • Fever
  • Painful urination (dysuria)
  • Increased urinary frequency
  • Increased urinary urgency


  • Blockage of the urinary system present at birth (congenital)
  • A kidney or ureteral stone (nephrolithiasis)
  • A blood clot
  • Scarring of the ureter, usually from injury, radiation therapy or previous surgery
  • A tumor in or around the ureter
  • Prostate gland enlargement (benign prostatic hyperplasia)
  • Pregnancy