What Is Ureteral Stone

Introduction 

Ureterolithiasis is a medical ailment where crystallised masses, known as ureteral stones, are situated in the ureteral tubes, the tubes that carry urine from the kidneys to the bladder. These stones form in the kidney, and are transported down the ureter tubes where they can become lodged and cause symptoms . uses of this urologic condition are prevalent around the world. Environmental factors like our diet mean kidney stones are rising in prevalence (Noh et al., 2023). As a result, ureteral stones are becoming a major public health issue particularly in dense regions with a hot climate (Wang et al., 2021). There are several clinical manifestations associated with ureteral stones, including a fever, an abnormal urine appearance alongside painful sensations whilst urinating. However, some ureteral stones remain silent within the ureter tubes presenting no notable symptoms. Manifestations that result from the presence of ureter stones include urinary tract infections, urosepsis and sometimes kidney disease (Wilcox et al., 2020). Therefore, quick and effective medical intervention is important to ensure damage to the ureter does not occur.

Anatomy of the ureter 

Two tubes bridge the kidneys to the bladder, called ureters which mirror each other . The urine travels directly to the bladder from each of the kidneys through these two tubes. During urine flow, smooth muscle contractions assist the movement of urine along the ureters. A ureter tube is approximately 25-30 cm in length, but length varies depending on the individual, with individuals assigned male at birth typically measuring longer tubes (Hickling D et., 2015). Ureteric tubes originate posterior (toward the back) of the renal vessels and extend down to the psoas muscles at the base of the spine (Hickling D et al., 2015). Furthermore, the ureter tubes are lined by fibromuscular tubes which assist in transporting material to the bladder (Hickling D et al., 2015). The ureter tubes enter through the bladder wall tissue and terminate internally as openings within the bladder to assist the transport of urine. 

The ureteropelvic junction, ureterovesical junction, and the ureter-iliac vessel region are three notable areas of the ureter (Hickling D et al., 2015). Ureteral stones tend to situate in these areas, causing blockages, and so these junctions are important to acknowledge. A blockage can lead to severe infections as the bacteria present in this region start to proliferate and spread throughout the urinary tract causing complications. 

The role of the ureter

As the primary role of the urinary tract is to remove waste from the kidneys, it prevents the buildup of toxic substances in the body. The transport process occurs through an outward flow of waste from the upper to the lower regions of the urinary tract (Hickling D et al., 2015). It is important to know that the anatomical structure of the urinary tract is crucial in dictating the recurrence and likelihood of infection. Despite its direct contact with the urethra, the urinary tract is surprisingly bacteria-free. However, circulating bacteria in the urinary tract can accelerate the build-up of struvite, eventually leading to the formation of a stone (Brain E et al., 2021). It is estimated that 80% of the time, new cases of urinary tract infections do not result in recurrences (Hickling D et al., 2015). Infections in the urinary tract become more likely when the sterile conditions are disturbed.

Ureteral stone formation

A kidney stone that moves from the kidney  to the urinary tract is considered a ureteral stone. Therefore, they are the same type of stone, but change in name depending on the location. Ureteral stones can be small and not visible to the naked eye, but also  much larger, which can block the flow of urine. Ureteral stones are formed by mineral clusters accumulating to form a crystallised  mass.

Typically, the ureters contain the following types of mineral masses:

• Calcium oxalate
• Uric Acid
• Struvite
• Cystine

Calcium oxalate remains the most common form of ureteral stone, particularly prevalent in individuals assigned male at birth (Wang et al., 2021). In 80% of cases, kidney stones are formed by this composition (Nojaba et al., 2023). Even though kidney stone formation has been studied, the exact pathology remains unclear, with further research needed. Crystallisation of urine is known to be a major factor in creating mineral masses, which consist of calcium oxalate, uric acids, and amino acids (Wang et al., 2021). Additionally, the type of stone that is formed is largely dependent on the surrounding pH of the urine. For example, a highly acidic pH leads to the creation of uric acid stones (Wagner C et a., 2010). Increased circulating calcium levels increase the risk of calcium stones, in particular. Risk factors for uric acid stones include chronic illnesses such as Crohn's disease and heavy alcohol consumption (Kaur P et al., 2023). Another form of crystallised mass includes struvite stones, which often present following infection along the ureters (Karki N et al., 2023). It is common for this form of mineral mass in particular to receive medical treatment because they are often large and can cause severe complications, therefore, intervention by surgery may be required. Cystine stones can be caused by the inherited condition cystinuria; the elevated levels of cystine in urine (Leslie S et al., 2023). People suffering from cystinuria are therefore more likely to develop cystine stones.

Symptoms

Urine stones generally cause sharp pains or dull aches in the ureter. The backs and sides of the stomach are commonly affected too. A burning sensation may also accompany urination or blood may present (Brown Urology, 2018). Ureteral stones can block the ureter, causing symptoms to worsen and in some cases a fever to develop. Other symptoms may include :

• An increase in body temperature
•  Nausea
• Urine with a cloudy or strong smell
• Vomiting
•  Loss of appetite

A range of factors can affect the development of ureteral stones, such as environmental factors and inherited conditions.  Risk factors include:

1. A family history of kidney stones
2. Calcium oxalate formation increases in the chances of malabsorption
3. Hydration deficiencies
4. Diabetes
5. Obesity 
6. Uric acid is formed when urine has an acidic pH

It is known that genetic factors can interplay with environmental risks to cause stones to form. Vitamin D receptors and tight junction proteins, for example, both contribute to calcium accumulation in the urine (Alelign et al., 2018). The kidneys can form calcium mineral masses that travel to the ureters as a result of this. 

Diagnostic tools

To determine the location and size  of a ureteral stone, physical exams are performed alongside assessing medical history. Imaging techniques such as CT scans and X-rays can provide insight into the mass, size and location. This is often accompanied by blood tests and urine samples which indicate the mineral and salt levels of which the stone is composed of. The presence of elevated calcium levels in the blood is also an indication of a stone (Sadiq N et al., 2022). It is also possible to perform an intravenous pyelogram, an injection of contrast material, to locate ureter stones (Mehta S et al.,2023). 

Treatment plan

Whenever ureteral stones are painful, nonsteroidal anti-inflammatory drugs (NSAIDs) can be administered as a first line of treatment. As well as reducing ureteral spasms, NSAIDs have anti-inflammatory effects (Nojaba et al., 2023). Opioids are often prescribed to those who suffer from severe pain. To support kidney function, hydration levels within the body must also be restored. To replenish the system, intravenous fluids are administered. It has been reported that tamsulosin may assist the passage of smaller ureteral stones that are larger than 5 mm (Nojaba et al., 2023). Since this is an alpha-adrenergic blocker, patients with low blood pressure should not take this medicine (Walter K., 2022). If the stone is accompanied by other interrupting symptoms such as a fever, surgical intervention may be necessary. When it exceeds 10mm and fails to pass through the urinary tract within six weeks, surgical removal is often required (Walter K., 2022). As a preventative measure, antibiotics may be administered after removing the stone to prevent the spread of new bacteria in the ureters (Preminger GM, 2023).

Extracorporeal Shock Wave Lithotripsy (ESWL)

Another method of medical treatment involves the use of ESWL which works to break down  the ureteral stone (Lingeman JE et al., 2009). This method uses a range of different approaches including technologies such as X-rays or ultrasounds. This device creates a stream of shock waves that radiate into the body and skin to help move stone particles out of the ureter.

Ureteroscopic  stone removal

To locate and assist with the removal of ureteral stones in the lower abdomen, fiberoptic ureteroscopes are used (Wright AE et al., 2014). During this method, a device that captures crystallised particles is used to allow the extraction of the stone. ESWL may also be used to break it down  (Cui Y et al., 2023).

Prevention strategy

Maintaining hydration, particularly by drinking water, is crucial for preventing kidney and ureteral stones. By assisting urine flow and preventing mineralisation, fluid aids the movement and passage of any potential ureteral stones (Siener R et al., 2021). Several other lifestyle factors can be implemented to lower the risk of ureteral stones. Additionally, diet is particularly important. By reducing consumption of oxalate-rich foods like chocolate, tea, spinach, and sweet potatoes, for instance (Siener R et al., 2021). Additionally, substituting legumes for red meat in the diet to replace animal protein could be beneficial. Finally, actively choosing a low-sodium diet will reduce the likelihood of forming a stone by lowering sodium intake in the body (Siener R eta., 2021). Diet and health are important factors in ureter and kidney stone risk, so it may be advisable to seek advice from a dietician.. 

Summary

A ureteral stone is a crystallised mineral mass found inside the urinary tract in the ureters. They can remain unnoticed in the tubes and cause little to no symptoms, but if they are large and cause obstructions, pain can accompany them. Calcium oxalate buildup is the most common cause of ureteral stones. Dehydration and elevated levels of mineral-forming components in the urine and blood put individuals at risk of stone formation. The size and location of ureteral stones play a significant role in how they pass through the urinary tract. Therefore, it is important to be aware of early kidney and ureteral stone symptoms to allow for early detection and treatment. In addition to alleviating pain, this can help improve the quality of life of affected individuals.