Bladder Stones

Bladder stones are endemic in some developing countries. The cause of this is unknown but dietary factors are probably important. Stones forming in the bladder do so as a result of:

• bladder outflow obstruction (e.g. urethral stricture, neuropathic bladder, prostatic obstruction)
• the presence of a foreign body (e.g. catheters, non-absorbable sutures).

Significant bacteriuria is usually found in patients with bladder stones. Some stones found in the bladder have been passed down from the upper urinary tract.

Pathology of Bladder Stones

Stones may be single or multiple and vary enormously in size from minute, sand-like particles to staghorn calculi or large stone concretions in the bladder. They may be located within the renal parenchyma or within the collecting system. Pressure necrosis from a large calculus may cause direct damage to the renal parenchyma and stones regularly cause obstruction, leading to hydronephrosis. They may ulcerate through the wall of the collecting system, including the ureter. A combination of obstruction and infection accelerates damage to the kidney.

When urinary tract obstruction is present, measures that increase urine volume, such as copious fluid intake or diuretics, including alcohol, make the pain worse. Physical exertion may cause mobile calculi to move, precipitating pain and, occasionally, haematuria. Calyceal colic - pain resulting from movement of stones within the calyces - is a real entity, but whether small calyceal calculi are the cause of backache or not is often difficult to decide.

Investigation of Bladder Stones

These should include a mid-stream specimen of urine for culture and measurement of serum urea, electrolyte, creatinine and calcium levels.

Plain abdominal X-ray, and excretion urography, are the mainstay of diagnosis although unenhanced helical (spiral) CT is increasingly used in developed countries. Advantages include speed (the examination takes 5-10 minutes), avoidance of contrast exposure and ability to diagnose non-renal causes of pain mimicking renal colic. There is an increased radiation dose. Renal tomography is still sometimes necessary. Ureteric stones can be missed by ultrasound.

Treatment of Bladder Stones

Adequate analgesia should be given, such as intramuscular morphine 10-15 mg repeated as necessary. Alternatively an NSAID can be tried. A high fluid intake and, if feasible, increased physical activity are recommended but the efficacy of these measures is doubtful.

Stones less than 0.5 cm diameter usually pass spontaneously and can be left. Stones greater than 1 cm diameter usually require intervention.