Kidney Stones (Urolithiasis) ICD-10-CM codes

Upper tract stones are category N20: N20.0 calculus of kidney (nephrolithiasis), N20.1 calculus of ureter, N20.2 calculus of kidney with calculus of ureter, and N20.9 urinary calculus unspecified. Lower tract stones are N21 (N21.0 bladder, N21.1 urethra). There is no laterality in these codes; document the side in the note. Staghorn calculus indexes to N20.0.

When the stone has caused hydronephrosis, N13.2 (hydronephrosis with renal and ureteral calculous obstruction) is the combination code and N20.- is not reported with it: N20 carries an Excludes1 note for calculus with hydronephrosis. N23 (unspecified renal colic) is a symptom code for flank pain suspected to be a stone before imaging confirms one; once the stone is identified, N23 is replaced by the N20 code. Hematuria that is integral to the stone presentation is not coded separately, but a documented hematuria finding on a visit unrelated to the stone may be R31.-.

A patient seen after stone passage with no stone present is Z87.442 (personal history of urinary calculi). Stones in a pregnant patient are sequenced after the chapter 15 code O26.83- for pregnancy-related renal disease. Calculus due to an underlying disease such as gout or hyperparathyroidism is N22, with the underlying disease coded first.