trematode Schistosoma haematobium, has been implicated in the development of vesical calculi. However, evidence accumulated thus far has not supported this hypothesis. 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. Classification Urinary stones may be composed of the following substances: 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) Jackstone calculus Jackstone calculi are rare bladder stones that have an appearance resembling toy jacks. They are almost always composed of calcium oxalate dihydrate and consist of a dense central core and radiating spicules. They are typically light brown with dark patches and are usually formed in the urinary bladder and rarely in the upper urinary tract. Their appearance on plain radiographs and computed tomography in human patients is usually easily recognizable. Jackstones often must be removed via cystolithotomy. 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. Men who have difficulty with urination due to prostate enlargement should seek treatment, however, urinating in a sitting position appears to improve bladder emptying which might decrease the risk of bladder stones forming. Prevention in newborn children, especially in the first three months of life when most stones begin, is critical. Studies show that feeding newborn infants milk (mother's, cow or goat) with no substitutes or supplements until at least the third month has proven successful in preventing most stones. Management Increasing fluid intake can facilitate the passage of small bladder stones. However, larger