Definition

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

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Causes

Hydronephrosis is caused by one of two problems in the urinary system:

    
  • A blockage, which can occur with kidney stones
  • Backflow of urine from the bladder to the kidneys—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
  • Symptoms

    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
  • Diagnosis

    Your doctor will ask 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.

    Tests may include:

        
  • Blood tests
  • Urine tests
  • Imaging tests evaluate the urinary system. This can be done with:

        
  • Abdominal ultrasound
  • IV urogram
  • CT angiography
  • MRI scan
  • Cystoscopy
  • Voiding cystourethrogram
  • Treatment

    A catheter may be inserted into the bladder to drain excess urine from the kidney. Some causes of hydronephrosis resolve without treatment, such as pregnancy and kidney stones.

    Treatment options include:

    Medications

    Depending on the cause, hydronephrosis may be treated with:

        
  • Antibiotics for infection
  • Medications for neurogenic bladder or to reduce excess uric acid excretion
  • Surgery

    Surgery is usually not needed, but it may be necessary in some cases. Procedures may include:

        
  • Removing a blockage or correcting a defect in the urinary system
  • 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).
  • Prevention

    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.