flat lay or top view very small kidney stones with ruler at white background

ammonium background biology block blue calculi caliceal care chemical clogged close dialysis disease disorder doctor eswl failure filter finger flat health healthcare internal kidney laser lay lithotripsy lithotripter macro magnesium man medical medicine pain painful phosphate problem renal ruler science sharp small specialist stone stones struvite surgery top treatment two ureter ureterolithiasis urethra urinary urologist very view waste white