Hydronephrosis occurs when urine builds up in the kidneys and cannot drain out to the bladder. The kidneys swell from the excess urine. The condition may affect one kidney or both. Hydronephrosis is not a disease itself, but rather a sign of another disease or condition affecting the kidneys. Swelling of the kidneys can lead to kidney damage.
This is a serious condition that requires care from your doctor. Most patients who have hydronephrosis will not know it until it has already damaged the kidney. Therefore, if you are at risk for this condition, it is important to be under the care of a physician.
Kidney, Ureter, Bladder, and Kidney Stone
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Hydronephrosis is caused by two problems in the urinary system. A blockage may prevent urine from draining out of the kidneys. Or a condition called reflux may cause urine to flow back into the kidneys from the bladder.
Conditions that may cause hydronephrosis include: A blockage or defect in the urinary system that is present at birthKidney stonesA blood clotScarring of the ureters (tubes that connect the kidneys to the bladder)A tumor in the pelvic area (such as bladder, cervix, colon, or prostate)Enlarged prostateEnlarged uterus during pregnancy
in the kidneys
Neurogenic bladderInjury to structures in the urinary system (eg, from surgery or trauma)
The following factors increase your chances of developing hydronephrosis: Defect in the urinary system that is present at birthCancers
in the pelvic area
Pelvic surgeryBlood-clotting disordersRecurrent urinary tract infectionsEnlarged prostateNeurogenic bladderPregnancy
Hydronephrosis may or may not cause any symptoms.
If symptoms occur, they may include: Pain in the back, waist, lower abdomen, or groinPersistent pain with urination or urinary frequency (from urinary tract infections)Increased urge to urinate or urinary incontinenceDribbling after urinationFeverNausea and vomitingUnexplained itching
Your doctor will ask about your symptoms and medical history, and perform a physical exam, which may involve examination of the pelvis or rectum to feel for blockages. You will likely be referred to a urologist and/or nephrologist for further diagnosis and treatment.
Tests may include: Urine tests—to check for blood, protein, bacteria, or other evidence of damage to the kidneysBlood tests—to check for evidence of damage to the kidneysBladder catheterization—a thin tube, called a catheter, inserted into the bladder to try to drain itAbdominal ultrasound
—a test that uses sound waves to examine the structures in the abdomen (in this case the kidneys, ureters, and bladder)
Intravenous urogram (or pyelogram)—an x-ray test that uses contrast dye to assess the structure and function of the kidneys, bladder, and ureters (may not be used if kidneys are damaged)Computed tomography angiography (CTA)
—a type of x-ray that uses a computer to make pictures of the kidneys, bladder, and ureters
Magnetic resonance imaging
—a test that uses magnetic waves to make pictures of the kidneys, bladder, and ureters
—a thin, lighted tube inserted through the urethra and into the bladder to examine the lining
Voiding cystourethrogram—x-rays of the bladder and urethra taken during urination after contrast dye is placed in the bladder
Treatment involves: Draining excess urine from the kidneyRemoving the blockageTreating conditions that cause blockage or refluxTreating infections in the urinary system
Some causes of hydronephrosis resolve without treatment (such as pregnancy and
Treatment options include: Antibiotics to treat urinary tract infectionsMedications (eg, anticholinergic drugs) to treat neurogenic bladderCatheter inserted into the bladder to drain the urineNephrostomy (a tube inserted into an opening in the midsection to drain urine from the kidney)Surgery to remove a blockage or correct a defect in the urinary systemSurgery
to remove 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
Kasper DL, Braunwald E, Fauci A, Hauser S, Longo D, Jameson JL, eds.
Harrison’s Principles of Internal Medicine
. 16th ed. New York: McGraw Hill; 2005.
Last reviewed October 2012 by Adrienne Carmack, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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