by LaRusso L



Hydronephrosis a build-up of urine in the kidneys. The kidneys swell from the excess urine which cannot drain into the bladder. The condition may affect one or both kidneys. Hydronephrosis is not a disease, but a symptom of a problem with the urinary system.
Kidney, Ureter, Bladder, and Kidney Stone
Copyright © Nucleus Medical Media, Inc.


Hydronephrosis is caused by one of 2 problems in the urinary system:
  • A blockage, which can occur with many types of obstruction, such as kidney stonesor abnormal growths
  • Backflow of urine from the bladder to the kidneys—known as vesicoureteral reflux

Risk Factors

Factors that may increase your chance of hydronephrosis include:
  • Defect in the urinary system that is present at birth
  • Scarring of the ureters, the tubes that carry urine from the kidneys to the bladder
  • Cancers in the pelvic area (bladder, cervix, colon, or prostate)
  • Persistent kidney or urinary tract infections
  • Blood-clotting disorders
  • Benign prostatic hyperplasia
  • Neurogenic bladder
  • Injury to structures in the urinary system, such as from surgery or trauma
  • Enlarged uterus during pregnancy


Hydronephrosis may or may not cause any symptoms. If symptoms occur, they may include:
  • Pain in the back, waist, lower abdomen, or groin
  • Persistent pain with urination or urinary frequency from urinary tract infections
  • Increased urge to urinate or urinary incontinence
  • Incomplete urination
  • Fever
  • Nausea and vomiting
  • Unexplained itching


You will be asked about your symptoms and medical history. A physical exam will be done. It may include a pelvic or rectal exam to feel for blockages. You may be referred to a urologist and/or nephrologist for further diagnosis and treatment.
Your bodily fuids may be tested. This can be done with:
  • Blood tests
  • Urine tests
Imaging tests may be done to evaluate the urinary system. This can be done with:


A catheter may be inserted into the bladder to drain excess urine from the kidney. Some causes of hydronephrosis may also be managed with observation, such as pregnancy and kidney stones.
Treatment options include:


Depending on the cause, hydronephrosis may be treated with:
  • Antibiotics for infection
  • Medications for neurogenic bladder or to reduce excess uric acid excretion


Surgery is not always needed, but it may be necessary in some cases. Procedures may include:
  • Removing a blockage or correcting a defect in the urinary system
  • Stent—A tube is placed from the kidney to the bladder to allow urine to drain past a blocked ureter.
  • Nephrostomy—A catheter is placed into the kidney. The catheter is attached to a urine collection bag.
  • Nephrectomy—Removal of part or all of the kidney (rare).


In general, the causes of hydronephrosis cannot be prevented. Prompt treatment of conditions that cause hydronephrosis reduces the risk of complications, such as kidney failure.


National Institute of Diabetes and Digestive and Kidney Diseases
National Kidney Foundation


Health Canada
Kidney Foundation of Canada


Hydronephrosis. National Kidney Foundation website. Available at: Published 2015. Accessed June 1, 2016.
Kidney disease and kidney failure. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: Accessed June 1, 2016.

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