• Most vesical calculi are formed de novo within the bladder, but some initially may have formed within the kidneys as a dissociated Randall plaque or on a sloughed papilla and subsequently may have passed into the bladder, where additional deposition of crystals cause the stone to grow. • Most renal stones that are small enough to pass through the ureters are also small enough to pass through a normally functioning bladder and an unobstructed urethra. • In older men with bladder stones composed of uric acid, the stone most likely formed in the bladder. • Stones composed of calcium oxalate are usually initially formed in the kidney. • In adults, MC type of vesical stone (seen in >50% of cases) is composed of uric acid. • Less frequently, bladder calculi are composed of calcium oxalate, calcium phosphate, ammonium urate, cystine, or magnesium ammonium phosphate (when associated with infection). Endemic Bladder Calculi • In children, stones are composed mainly of ammonium acid urate, calcium oxalate, or an impure mixture of ammonium acid urate and calcium oxalate with calcium phosphate. • The common link among endemic areas relates to feeding infants human breast milk and polished rice. • These foods are low in phosphorus, ultimately leading to high ammonia excretion. • These children also usually have a high intake of oxalate-rich vegetables (increased oxalate crystalluria) and animal protein (low dietary citrate). • Vesical calculi may be single or multiple, especially in the presence of bladder diverticula, and can be small or large enough to occupy the entire bladder. They range from soft to extremely hard, with surfaces ranging from smooth and faceted to jagged and spiculated (“jack” stones). • Most bladder stones are secondary, more common in older males (>50 years), usually because of bladder outlet obstruction. • MC type: Uric acid (sterile urine) > Struvite stones (Infected urine) • Bladder stones are usually solitary, multiple in 25% patients. Etiology • Bladder outlet obstruction (MC cause) • Neurogenic bladder • Foreign body (Foley’s catheter, forgotten DJ stents) • Bladder diverticula Clinical Features • Typical symptoms are intermittent, painful voiding and terminal hematuria with severe pain at the end of micturition. • Pain may be referred to the tip of the penis or to the labia majora. Diagnosis • A large percentage of bladder stones are radiolucent (uric acid). • USG bladder: Identifies the stone with its characteristic shadowing and stone moves with changing body position. Treatment • Small stones: Removed or crushed transurethrally (Cystolitholapexy) • Larger stones: Disintegrated by transurethral electrohydraulic lithotripsy or Cystolithotomy Stones of Genitourinary Tract • MC renal stone: Calcium oxalate • MC primary bladder stone: Ammonium urate • MC bladder stone: Uric acid >Struvite • MC prostate stone: Calcium phosphate