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Urinary Tract Blockage

 

What is urinary tract blockage?

Urinary tract obstruction is blocked or restricted flow of urine at any point in the urinary tract. The kidneys, ureters (tubes from the kidneys to the bladder), bladder, urethra (tube from bladder to outside of the body), or any combination may be involved.

What causes urinary tract obstruction?

Any process that interferes with normal flow of urine through the urinary tract can cause a blockage. Urine accumulates behind the obstruction, and increasing pressure within the system causes cell and tissue death. Obstruction can occur in one or both kidneys, one or both ureters, or in the bladder or urethra. Blockage of the urethra is most common.

Causes of urinary tract obstruction include:

What are signs of urinary tract obstruction?

The signs of urinary tract obstruction vary, depending on the site of obstruction, the duration of the obstruction, and the underlying cause. The signs also depend on the extent of the obstruction. The animal is unable to urinate if the obstruction is located in the urethra and is a complete obstruction. However, if the obstruction involves only one kidney or ureter or is a partial obstruction, the animal should be able to pass some urine. The kidneys produce urine and it is excreted from the body through the urinary tract. Urine removes many toxic products from the body. If the flow of urine is blocked, these toxic products can build up in the system, making the animal seriously ill. When this happens, the animal is "uremic" or "azotemic." Uremia and azotemia refer to the build up of toxic, nitrogenous products in the blood.

Signs of urinary tract obstruction may include straining to urinate with little or no urine passed. The animal may pass only a few drops of urine or may dribble. The urine stream may be more narrow than normal and the animal may urinate with less force. The animal may have abdominal discomfort or swelling. Prolonged obstruction leads to lethargy, dull attitude, reduced appetite, and vomiting. Urinary tract obstruction is an emergency medical condition.

How is urinary tract obstruction diagnosed?

Urinary tract obstruction is diagnosed by medical history and physical examination. Physical examination findings will reflect the location of the obstruction. Enlargement of the kidney or bladder may be identified. The animal may react painfully to the veterinarian feeling the abdomen (abdominal palpation). Additional diagnostic tests will be performed. Blood test results, especially blood urea nitrogen (BUN), creatinine, phosphorus, and potassium, are altered during urinary tract obstruction. Blood clotting (coagulation) tests may be performed. When urine is available for examination, it often contains elevated amounts of blood and protein. Crystals are seen commonly in urine from obstructed cats.

Imaging studies are helpful in the diagnosis of urinary tract obstruction. Imaging techniques may include radiographs (X-rays), contrast radiographs, or ultrasound (visualization of deep body tissues by recording ultrasonic waves). Passage of a urinary catheter often relieves the obstruction, locates the specific site of the blockage, and allows retrieval of material for analysis. Stones voided or obtained during catheterization or at surgery may be analyzed for mineral content. Biopsy (surgical removal and microscopic examination of tissue) may be necessary, especially for cancer. Electrocardiography (ECG or EKG, an electrical analysis of the heart) may detect abnormal heartbeats and rhythm caused by accumulation of high levels of potassium in the blood.

How is urinary tract obstruction treated?

Complete blockage of the urinary tract is a life-threatening emergency. Treatment must begin immediately. Generally, fluid therapy to correct dehydration and electrolyte abnormalities begins first. Correction of high potassium levels is crucial as they can poison the heart. The obstruction must be relieved. A urinary catheter may be passed for urethral obstruction. Some pets require immediate surgery. After the obstruction is relieved, monitoring of urinary function, hydration status, and body temperature is required. Urinary tract obstructions may recur; therefore, the animal's ability to urinate must be checked.

What is the prognosis for animals with urinary tract obstruction?

The prognosis (outcome) for animals with urinary tract obstruction depends on the location of the obstruction, the duration of the obstruction, and the underlying cause. Some patients die from urinary tract obstruction. Death may occur during the crisis, during treatment, or even after the correction of the obstruction. When the obstruction is detected early, prior to significant derangement in heart and urinary tract function, the prognosis can be very good. Prognosis for cancer of the urinary tract depends on the type, location, and degree of growth.

The information on this page was obtained from the site www.vetmedcenter.com