Prevention and Treatment of Stones in the Urinary Tract

Stones (calculi) in the urinary tract are known to affect and significantly reduce the quality of life of those affected due to the pain and the high rate of infection. Being a disease of the working class, it exerts a huge burden on the economy as well. Therefore, prevention of the formation of stones is important and it can be achieved by some simple alterations to the life-style. Once diagnosed with a stone, seeking for early treatment and opting for the correct modality of treatment is important for a better outcome. Therefore, this hub is aimed at educating the lay people as well as the medical professionals regarding the prevention and treatment of urinary calculi.

The life-style could be easily adjusted to prevent the formation of urinary calculi, especially if the individual had previous experience of the disease or if the individual is living in an area with a higher risk of developing calculi. The measures that could be taken include:

1.       Increase intake of water

The intake of water should be increased to achieve a urine output of 2 liters per day. The intake of water to achieve this goal differs depending on the climate and the physical activity. However, over consumption of water can also lead to stone formation as then the urine is diluted leading to the dilution of the inhibitors of stone formation.

2.       Dietary modifications

Addition of at least one citrus fruit (lime, lemon, orange) to the diet every day has a significant effect in reducing the formation of stones. Intake of dietary calcium and oxalate should not be too high or low. Food of animal origin also should not be consumed in high quantities as these can lead to the formation of urate stones. The intake of salts should be reduced. Inhibitors of stone formation such as citrate, magnesium and micro-minerals (e.g. – zinc, molybdenum) should be included in the diet adequately. This could be achieved by the intake of adequate amounts of vegetables and fruits.

3.       Drugs (only when at a very high risk)

Drugs such as Potassium citrate may be taken by those who are at a very high risk of formation of phosphate stones. Those who are being treated for tumours with anti-cancer drugs may be advised to take Allopurinol to prevent the formation of uric acid stones.

Once diagnosed, management of a stone is complex and depends on,

1. Size of the stone (smaller stones can be managed conservatively)

2. Location of the stone (stones in the lower urinary tract may be managed conservatively)

3. Type of the stone (some stones can be dissolved with correct treatment)

4. Degree of obstruction to the flow of urine (obstruction always indicate the need for urgent intervention)

5. Presence or absence of infection (infection also require urgent intervention)

6. Shape of the stone (certain shapes are not compatible with conservative management)

7. Condition of the patient (the general condition and, functional status of the kidneys should be considered)

As the main complain of stones in the urinary tract is pain, any patient is usually prescribed analgesics (pain killers) such as diclofenac sodium. If the stone is complicated by infection or obstruction, immediate drainage of urine may be necessary and is usually carried out through a tube inserted to the outflow pathway of the affected kidney (nephrostomy). As this has the risk of excessive and continuous bleeding, certain blood tests are carried out prior to the test to evaluate the ability to clot and stop bleeding. Nephrostomy may be life saving or at least saving the kidney as it relieves the pressure exerted by the urine on the kidney and causing damage. It is performed under the cover of high doses of antibiotics to prevent spreading of infection to other organs during the procedure.

If not complicated as described above, the management of a stone in the urinary tract could be by several methods.

1. Active monitoring with stone expulsion therapy (for small stones in the lower urinary tract)

2. Medical management of stones (only applicable to uric acid stone)

3. Ureteric stenting

4. Extra-corporeal shock wave lithotripsy (ESWL – shattering the stone using ultrasound waves)

5. Percutaneous nephrolithotomy (PCNL – removal of a stone in the kidney using a small tunnel created through the skin)

6. Ureteroscopic removal / destruction (using a special endoscope inserted through the urethra into the urinary tract)

7. Open surgical removal (e.g. – nephrolithotomy, pyelolithotomy, ureterolithotomy, cistostomy)

1. Active Monitoring with Stone Expulsion Therapy

This can only be used for small stones (less than 0.5 cm) in diameter. The patients are given non-steroidal anti-inflammatory drugs such as diclofenac sodium even in the absence of pain and are asked to increase the physical activity (e.g. – skipping, jumping and swimming). The intake of water should not be excessive as this can cause unnecessary strain on the kidneys and diuretics are avoided for the same reason. Drugs may be given at the same time to facilitate the expulsion of the stone (e.g. – Prazosin, Nifedipine, Prednisolone).

2. Medical Management of Stones

This is applicable only to uric acid stones the presence of which is usually confirmed by an ultra-sound scan. The stones are forced to be dissolved by changing the composition of urine using certain drugs (e.g. – Allopurinol and Potassium citrate). At the same time the patients are asked to drink at least 4 liters of water per day and to reduce the intake of meat and fish so that amount of uric acid in urine would be less, facilitating the dissolving process.

3. Ureteric Sternting

Stenting is applicable only to small stones which are likely to pass down the ureters. This is done under spinal anaesthesia using a cystosope (a special endoscope with a light and a camera through the urethra). A stent is a synthetic wire, which prevents spasm of the ureters and by this facilitates the descent of a stone in the ureters and the kidney to the lower urinary tract so that it can come out with micturition (passage of urine). The stent can be removed after confirming the expulsion of the stone with an X-ray (usually in 3 months from the insertion).

4. Extra-Corporeal Shock Wave Lithotripsy (ESWL)

This technique has become quite famous as it is convenient and pain-free in most instances. This can be used on large stones in the kidneys, markedly reducing the need for surgery. The stone is shattered into pieces using an ultra-sound beam focused at the stone. A stent is almost always inserted prior to undergoing this treatment to facilitate the expulsion of the small parts of the shattered stone. The patients are also advised to drink a large amount of water before treatment as well as for 3-4 days after the treatment. Some large stones may need several attempts of shock-wave lithotripsy until the stone is fully expulsed. This technique however, is less effective to treat the stones in the lower ureters and the urinary bladder.

Contraindications for ESWL (When should ESWL be Avoided)

· Pregnancy

· Infection

· Hypertension (high blood pressure)

· Heart disease

· High tendency to bleed

· Weight more than 130 kg (ineffective)

Side Effects of ESWL

· Passage of blood with urine for several days

· Pain and discomfort due to the passage of stone fragments

· Bruising and discomfort of the abdomen

· Damage to other organs in the abdomen (extremely rare)

5. Percutaneous Nephrolithotomy

Stones in the kidneys may be removed via a tunnel created from the skin to the kidneys after insertion of a special instrument through that tunnel. This technique is also becoming famous as it can be applied when ESWL is contraindicated. This has the advantages of avoiding the risks associated with open surgery and ESWL. The main disadvantages are the risk of excessive bleeding and the risk of introducing infection through the tunnel of access.

6. Ureteroscopic Removal / Destruction

The stones in the ureters and the kidney can be accessed using a special instrument called ureteroscope with a light and a camera, inserted through the urethra (the outflow tract of urine). After the stone is reached there are several methods to destruct or remove the stone. The small stones in the lower ureter can be dragged out using a basket device (known as Domia basket extraction). A hammer like device known as lithoclast can be used to shatter the stone. Ultrasound waves can also be used in the ureter with a local devicde to shatter the stone. Finally, laser beams emitted from the ureteroscope can be used to burn the stone down within the body.

7. Open Surgery

If all the above measures are not applicable due to the large size of the stone or due the lack of instruments or the expertise the stones can always be removed with open surgery. This has the disadvantages of the need for a large skin incision and the need to perform under general anaesthesia as the surgery is long. The recovery is also prolonged and there fore open surgery is avoided as much as possible in current practice.

The best method for the individual patient should be selected from the methods described above depending on the stone and its location as well as the needs of the patients. However, prevention is always easier than attempts to treat the disease. So, it is always better for those who are at risk to take measures to prevent the occurrence of stones.