Ureteral stones are rocklike accumulations that form from naturally occurring mineral salts in the urine. Most stones form in the kidney and migrate into the kidney tubes or ureters. The typical patient with urinary stones is a 40- to 50-year-old white man with a family history of urinary stones.
Urinary stones can be round or irregular, relatively smooth, or have jagged edges or projections. The color of urinary stones varies according to their chemical composition.
Stones can remain in the kidneys for years without causing problems.
WHAT ARE THE SYMPTOMS?
The first symptom of a stone lodged in the ureter is usually severe pain in the back or on either side of the abdomen or flank. The pain may radiate into the groin, to the labia in women, or to the scrotum in men. A burning sensation may accompany urination or blood may be in the urine. If the urinary system fails to expel the obstruction, the pain will become more severe and constant. In addition to the severe pain, other symptoms may include:
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- Strong, frequent urges to urinate;
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- Chills, fever, or cloudy or foul-smelling urine because of infection; and
CAUSES AND RISK FACTORS
Stones form when the naturally occurring mineral salts in the urine accumulate and become lodged in the ureter.
Different types of urinary stones have different causes. For example:
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- Calcium stones: The most common form, calcium stones occur when there is too much calcium and/or oxalate in the blood. Taking certain drugs or too much vitamin D can increase calcium concentrations. Genetics or a diet high in oxalate-rich foods, such as spinach, can elevate oxalate levels.
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- Uric acid stones: Excess uric acid, a byproduct of protein metabolism, can crystallize to form stones.
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- Struvite stones: Struvite stones are created by bacteria that infect the urinary tract more commonly in women.
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- Cystine stones: These rare stones occur in people with a hereditary condition that causes the kidneys to excrete large amounts of certain amino acids.
By one estimate, 1 in 10 people will develop urinary stones sometime during their life. Risk factors include:
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- Gender (stones typically occur in men);
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- Age (most stones occur in men between the ages of 40 and 60);
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- Lifestyle: (factors include being sedentary, eating a diet high in animal protein, and not drinking enough water);
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- Family history of stones; and
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- Chronic urinary tract infections.
DIAGNOSIS
The first step during medical evaluation is a physical examination intended to locate the exact source of any pain or discomfort. Other diseases that produce symptoms similar to ureteral stone disease must be considered and eliminated.
A physician may also order one or more of the following tests:
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- 3D computerized imaging without contrast agent; or
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- Intravenous pyelogram (a medical dye is injected into the bloodstream to provide visual contrast on the x ray, allowing the physician to clearly see the stone and assess the degree of obstruction).
TREATMENT APPROACH
In many cases, small ureteral stones eventually will harmlessly exit the body on its own. Patients are often prescribed pain medication and instructed to drink as many as 12 to 16 glasses of fluid a day during the waiting period. An expelled stone should be captured, if possible, to allow analysis of its chemical composition.
If the stone is not expelled or it presents an immediate threat to a patient’s health, minimally invasive or surgical procedures can be used to remove the stone. They include:
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- Lithotripsy (sound waves created outside the body pulverize the stones inside the body);
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- Ureterorenoscope: (which allows the surgeon to view and extract stones through the urinary opening. Once the stone has been located, the surgeon can grasp it with tiny tweezers and remove it, or fragment the stone using sound waves or a laser); and
