Bladder stone

A bladder stone (also called a vesical calculus or cystolith) is a solid concretion or crystal aggregation found in the urinary bladder. The term cystolithiasis refers to the presence of stones in the bladder.

Classification

Urinary stones may be composed of the following substances:^[1]

• Calcium oxalate monohydrate (whewellite)
• Calcium oxalate dihydrate (weddellite)
• Calcium phosphate
• Magnesium phosphate
• Ammonium phosphate
• Ammonium magnesium phosphate (struvite)
• Calcium hydroxyphosphate (apatite)
• Uric acid and its salts (urates)
• Cystine
• Xanthine
• Indigotin (rare)
• Urostealith (rare)
• Sulfonamide (rare)

Signs and symptoms

Bladder stones are small particles that can form in the bladder. In most cases bladder stones develop when the urine becomes very concentrated or when one is dehydrated. This allows for the minerals like calcium or magnesium to crystallize and form stones. Bladder stones vary in number size and consistency. In some cases bladder stones do not cause any symptoms of signs and are discovered as an incidental finding on a plain radiograph. However, when symptoms do occur these may include severe lower abdominal and back pain, difficult urination, frequent urination at night, fever, painful urination and blood in the urine. The majority of individuals who are symptomatic will complain of pain which comes in waves. The pain may also be associated with nausea, vomiting and chills.^[2]

Bladder stones vary in their size, shape and texture- some are small, hard and smooth whereas others are huge, spiked and very soft. One can have one or multiple stones. Bladder stones are somewhat more common in men who have prostate enlargement. The large prostate presses on the urethra and makes it difficult to pass urine. Over time stagnant urine collects in the bladder and minerals like calcium start to precipitate. Other individuals who develop bladder stones include those who have had spinal cord injury, paralysis or some type of nerve damage. When nerves to the back are damaged, the bladder cannot empty and stagnant urine results.^[3]

Causes

Bladder stones may occur whenever the kidneys, bladder, or ureters become inflamed. The use of urinary catheters may cause a bladder stone. Individuals who are paralyzed or are unable to adequately pass urine may require the use of small plastic tubes (catheters) placed into the bladder. The use of these tubes may lead to an infection, which irritates the bladder, resulting in stone formation. Finally, a kidney stone may travel down the ureter into the bladder and become a bladder stone. There is some evidence indicating that chronic irritation of the bladder by retained stones may increase the chance of bladder cancer. Urinary schistosomiasis, a disease caused by the digenean trematode Schistosoma haematobium, has been implicated in the development of vesical calculi.^[4][5] However, evidence accumulated thus far has not supported this hypothesis.^[6][7]

Diagnosis

The diagnosis of bladder stone includes urinalysis, ultrasonography, x rays or cystoscopy (inserting a small thin camera into the urethra and viewing the bladder). The intravenous pyelogram can also be used to assess the presence of kidney stones. This test involves injecting a radiocontrast agent which is passed into the urinary system. X-ray images are then obtained every few minutes to determine if there is any obstruction to the contrast as it is excreted into the bladder. Today, intravenous pyelogram has been replaced at many health centers by CT scans. CT scans are more sensitive and can identify very small stones not seen by other tests.^[8]

Prevention

The best way to prevent bladder stones is to drink plenty of liquids. Juices containing citrates are thought to reduce the risk of stone formation. A study published in the Clinical Journal of the American Society of Nephrology indicate orange juice is more effective at preventing stone formation than other citrus juices.^[9] Men who have difficulty with urination due to prostatic hypertrophy should seek treatment.^[10]

Management

Increasing fluid intake can facilitate the passage of small bladder stones. However, larger stones may require other methods of treatment.^[11] Fragmentation of bladder stones can be achieved by use of a cystoscope which is inserted into the bladder. The urologist visualizes the stone and uses ultrasonic energy or laser lithotripsy to cause fragmentation of the stones into small pieces which are then flushed out of the bladder. This procedure requires anesthesia and may require admission to a hospital. Complications of this treatment include infection and damage to the bladder.^[12] Some stones are too large even for cystoscopic treatment and may require open cystotomy, in which an incision is made in the bladder and the stones are removed manually.

History

Lithoclastic cystotomy is attributed to Ammonius Lithotomos (stone-cutter) of Alexandria, Egypt. The term "lithotomy" is derived from the same words (λιθοτομία (lithotomia) - stone-cutting). Aulus Cornelius Celsus wrote that Lithotomos developed instruments to break up and extract bladder stones.^[13] Celsus gave the first description of lithotomy as performed before and during his time, and the operation has ever since borne his name—the Celsian method.^[14]

References