About Hydronephrosis

Hydronephrosis is a condition that is characterized by swelling of the kidneys due to a blocked urinary passage, which connects the kidney to the bladder. The blockage prevents the urine from being discharged, which causes pressure to build up in the kidneys. Hydronephrosis is not a disorder in itself but is a condition caused by a number of different factors. Unilateral hydronephrosis is the dilation of one kidney, while bilateral hydronephrosis is the dilation of both kidneys. Bilateral hydronephrosis can lead to kidney failure if left untreated.

Significance

• The urinary canal that connects each kidney to the bladder is called the ureter. The point where the ureter connects to the kidney is called the ureteropelvic junction. Hydronephrosis can be caused by an obstruction either at the ureteropelvic junction or in the ureter. Such an obstruction causes the urine to build up in the kidney, which starts swelling. This puts immense pressure on the interior of the kidney, which can permanently damage the muscles that push the urine out of the kidney. Once these muscles are damaged, the kidney can no longer function properly.

Causes

• The most common reason for hydronephrosis is an obstruction at the ureteropelvic junction, which prevents the urine from leaving the kidneys. Such an obstruction can be caused by underdeveloped renal muscles due to a birth defect, a change in kidney position, kidney stones or blood clots, deformed arteries, tumors, and cancers of nearby organs. The ureter can become obstructed for the same reasons. In men, prostate enlargement can prevent urine from flowing out of the bladder, which also puts pressure on the kidneys. In women, complications during pregnancy can cause hydronephrosis.

Symptoms

• The symptoms of hydronephrosis vary. They depend on the condition that causes the blockage and on the severity of the blockage. Acute hydronephrosis----when there is a sudden obstruction----produces severe, sporadic pain in the region around the obstruction (anywhere between the ribs and the thigh). People suffering from chronic hydronephrosis----when the obstruction progresses gradually----may experience mild pain and discomfort or no symptoms at all. An obstruction at the ureteropelvic junction may cause nausea and vomiting along with the pain.

Diagnosis

• It is important to diagnose hydronephrosis as soon as possible, before the affected kidney becomes permanently damaged. A physical exam can generally expose a swollen kidney. Imaging tests like ultrasonography, computed tomography and intravenous urography are used to determine the site of the obstruction. Exploratory endoscopy is also an option if the imaging tests are inconclusive.

Treatment

• Since hydronephrosis is not a disease in itself, the treatment depends on the cause of the blockage and is generally aimed at relieving the cause. Different surgical procedures can be performed to remove the obstruction and drain excess amounts of urine.