Definition

Ureterolithiasis refers to the presence of stones in the ureter, the passage that carries urine from the kidney to the bladder. While some stones can pass through the ureter without causing symptoms, others may become trapped and block the ureter. Larger stones are more likely to cause blockages, resulting in sudden and severe abdominal pain.

Ureterolithiasis is a common condition affecting millions of people worldwide, with a higher prevalence among middle-aged adults. It's estimated that there's a 1 in 8 chance of developing stones in one's lifetime.

Causes

The main mechanism behind the formation of stones is an imbalance in the substances that compose them, coupled with insufficient fluid to dissolve them. The primary chemical compositions of urinary tract stones are as follows:

• Calcium (70-80%): Calcium stones are the most commonly encountered, constituting about 80% of all ureterolithiasis cases. They typically form in individuals with elevated calcium and oxalate levels in their bodies. Factors contributing to their formation include increased calcium consumption, enhanced calcium absorption in the intestines, excessive calcium absorption from the bones (e.g., in hyperparathyroidism), and kidney disorders impairing calcium absorption.
• Struvite or magnesium ammonium phosphate (10-15%): Struvite stones are commonly linked to chronic urinary tract infections caused by bacteria. These bacteria have the ability to break down urea into ammonium, which then combines with phosphate and magnesium to form struvite stones. Bacteria known to cause this condition include Proteus, Pseudomonas, and Klebsiella. Unlike other types of stones, the infection associated with struvite stones will not resolve until the stone is removed. Struvite stones are more frequently found in women, who are also at a higher risk of kidney swelling due to infection.
• Uric acid (6-9%): Uric acid stones are associated with excessive consumption of purine-containing foods such as organ meats, fish, and legumes. They can also result from cancer processes and are often linked to gout, a joint inflammation caused by the accumulation of uric acid crystals.
• Cystine (1-3%): Cystine stones are the rarest type and stem from metabolic disorders that hinder the kidneys' ability to absorb cystine, leading to its accumulation in the urine and subsequent stone formation.

Risk factor

Ureterolithiasis typically affects individuals aged 20 to 49 years, with the peak incidence occurring between 35 to 45 years old. Symptoms of stones rarely manifest for the first time in individuals over 50 years old or in children under 16 years old. Men are at a threefold higher risk of developing urinary tract stones compared to women. Additionally, individuals of Asian and white descent have a higher susceptibility to urinary tract stones compared to those of African American, African, and Hispanic descent.

Several other conditions are associated with urinary tract stones, including obesity, high blood pressure, and osteopenia (reduced bone density).

The primary factor in stone formation is inadequate fluid intake. When insufficient fluid intake, urine production decreases, resulting in higher concentrations of stone-forming substances, such as calcium and oxalate, in the urine. The diet also plays a crucial role in stone formation. A diet high in animal protein, and salt, and low in fluids and calcium increases the risk of urinary tract stone formation.

Symptoms

While urinary stones formed in the kidney typically do not cause acute or sudden pain, once the stones move into or reach the ureter, they can lead to severe pain and discomfort. This pain is often described as excruciating and may be more intense than childbirth. The pain tends to come and go and is typically accompanied by abdominal and back pain.

The presence of stones in the ureter can cause irritation, leading to the appearance of blood in the urine. The urine may appear pink or red, or small amounts of blood may require microscopic examination of a urine sample.

Diagnosis

The initial step in diagnosing ureteral stones is a urine examination. Additionally, a urine culture test, which involves culturing bacteria in the urine on specific media, may be performed to detect or rule out bacterial infections in the urinary tract.

While kidney function tests are not routinely performed, they may be utilized in individuals with a history of kidney disease or those experiencing complications such as significant kidney swelling. Stone analysis can help determine the composition of the stone, enabling the selection of appropriate therapy and prevention measures.

Imaging tests such as X-rays, CT scans, and ultrasonography are valuable in evaluating the presence of stones. X-ray examination is particularly useful for confirming the diagnosis, as 80% of urinary tract stones consist of calcium and are visible on X-ray. CT scans provide detailed information on the location, size, number of stones, and kidney swelling.

Although ultrasonography (USG) has limitations, such as difficulty detecting stones outside the kidneys and potential interference from body fat and gas in the gastrointestinal tract, it offers benefits as it does not emit ionizing radiation. This makes it safe for pregnant women, women of childbearing age, and patients with recurrent stones who have undergone multiple CT scans.

Management

In patients experiencing severe pain due to urolithiasis, the initial approach typically involves administering pain relievers. Additionally, medication for nausea and vomiting may be prescribed to alleviate these symptoms if present. Doctors may also recommend medication to relax the muscles of the ureter, widening its diameter to facilitate the passage of the stone into the bladder. The choice of medication depends on each individual's condition and is determined by the attending physician.

Once the symptoms are relieved, therapy to eliminate the stone becomes necessary. Approximately 80% of small stones (<4 mm) can pass spontaneously into the bladder. However, larger stones often require specialized surgical procedures to break them up.

If the composition of the stone is known, specific therapy tailored to that stone type can be implemented. For example, for struvite stones, therapy for urinary tract infection is provided. In the case of cystine stones, therapy may involve dietary adjustments or the administration of drugs that bind cystine compounds.

Complications

Complications that can arise from ureterolithiasis include:

• Urinary tract infection: Stone blockage can disrupt urine flow, leading to urinary tract infections. The presence of stones accompanied by infection complicates therapy and may cause symptoms such as fever, chills, and pain
• Injury or scarring of the ureter
• Bleeding
• Kidney function impairment: Chronic kidney failure may occur due to urological medical procedures (rarely) or blockage caused by kidney stones

Prevention

Ureterolithiasis, or stones in the ureter, typically occurs due to kidney stones. If you have a history of kidney stones, your doctor will work to determine the composition of the stones to help prevent their recurrence. Therapy may be initiated before the stone descends into the ureter and causes pain, aiming to mitigate the risk of ureterolithiasis.

Dietary measures to prevent stone formation generally include:

• Drinking plenty of water according to individual needs
• Limiting animal protein sources such as meat, eggs, and fish intake
• Restricting salt intake to less than 2 grams per day
• Limiting consumption of oxalate-rich foods such as spinach, nuts, and grains

In cases of recurrent stone formation, your doctor may also prescribe medication to help prevent the formation of kidney or ureteral stones.

When to see a doctor?

It's important to seek immediate medical attention if you experience symptoms such as:

• Severe pain that prevents you from sitting still or finding a comfortable position.
• Pain accompanied by nausea and vomiting
• Pain accompanied by fever and chills
• Blood in the urine
• Difficulty urinating

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