<prompt> The commonest bladder stone is:Triple phosphateXanthineUric acidCysteine  <response>: Bladder stone Primary bladder stone- Aka Endemic bladder calculi- Most common type of primary bladder stone - Ammonium urate - other stones- Calcium oxalate. Secondary bladder stone - More common in elderly males due to BPH Bladder outlet obstruction- Most common type of secondary bladder stone - Uric acid Struvite- Overall secondary bladder stone - most common Investigations- Investigation of choice- Ultrasound Treatment- For small stones - cystolitholapexy- For Large stones Electrohydraulic lithotripsy Suprapubic cystolithotomy 