Figure 1: A plain KUB showing a large smooth oval radio-opaque mass suggesting a calcified bladder stone
(Click on image to enlarge)
IMAGE OF THE WEEK 2013
WEEK 13
BLADDER STONE
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Figure 1: A plain KUB showing a large smooth oval radio-opaque mass suggesting a calcified bladder stone (Click on image to enlarge) |
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Bladder (vesical) stones or calculi are calcified materials that have collected and deposited over time, consisting of uric acid (>50%), calcium oxalate, calcium phosphate, ammonium urate, cysteine or magnesium ammonium phosphate.
Most vesical calculi originate within the bladder due to urinary stasis, but some may initially form within the kidneys and subsequently passed into the bladder. Besides stasis, other causes include urinary strictures such as bladder outlet obstruction, prostate enlargement, urinary infections and presence of foreign bodies in the bladder such as a double J ureteric stents or prolonged catheterisation. Bladder inflammation secondary to radiation therapy or in endemic areas, infection with schistosomiasis can predispose to bladder stones formation. Metabolic abnormalities are uncommon cause of calcium and struvite bladder stones.
The incidence of bladder stones in the western countries has steadily declined since the 19th century. However, the incidence of bladder stones in less developed countries and areas such as South-east asia, Middle east and North Africa still remains high.
The clinical presentation of bladder stones ranges from asymptomatic to suprapubic pain, dysuria, intermittency, frequency, hesistancy, nocturia and urinary retention. Other signs include terminal gross haematuria and sudden painful termination of voiding. Patients may also present with frequent and repeated urinary tract infection. Physical examination may revealed suprapubic tenderness, fullness and distended bladder.
Investigations include a simple urinalysis (Dipstik) which may test positive for nitrite, leucocyte and blood. MSU for culture is indicated. Other tests include, FBC for HB and white cell count, renal panel to exclude renal dysfunction from outlet obstruction and a comprehensive metabolic panel.
The initial radiological investigation of choice is a plain KUB – Kidney, ureter and bladder xray like the one shown above in Figure 1. More than 80% of bladder stones are calcified and a plain KUB should be sufficient to make the diagnosis. If a KUB is negative, then an ultrasound of a full bladder can help to differentiate a calculus from tumour or clot. CT scan are usually not indicated unless there are other associated abdominal symptoms. Cystoscopy is the most commonly used evaluative as well as therapeutic procedure for bladder stones.
Treatment of bladder stones aim at removing the calculi as well as treating the underlying problem such as bladder outlet obstruction, infections, foreign body or diet.
Pharmacologic dissolution of stones involved urinary alkalization using potassium citrate 60mEq/day. Beware that over alkalization may predispose to calcium phosphate deposits on the stone surface. Other solutions used for dissolution include Suby G or M solution and Renacidin for phosphate or struvite calculi.
Improving bladder emptying in bladder stasis caused by prostate enlargement using alpha-blockers and 5-alpha-reductase should further reduce the overall incidence of bladder stones.
Surgical modalities include transurethral cystolitholapaxy, percutaneous suprapubic cystolitholapaxy and open suprapubic cystotomy.
Images contributed by
Dr Ian Bickle, Department of Radiology,RIPAS Hospital
Text prepared by
Dr Chong Chee Fui, Department of Surgery, RIPAS Hospital
All images are copyrighted and property of RIPAS Hospital.
