ICD-10-CM 2027
ICD-10 code for Suburethral calculus
From the official ICD-10-CM alphabetic index entry “Calculus, calculi, calculous › suburethral”. Page updated September 29, 2026.
About coding Suburethral calculus
The ICD-10-CM code for Suburethral calculus is N21.8 (Other lower urinary tract calculus).
Within N21, choose N21.8 (Other lower urinary tract calculus) only when documentation doesn't support a more specific option: calculus in bladder (N21.0), calculus in urethra (N21.1) and unspecified (N21.9).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 693 (Urinary Stones with MCC, relative weight 1.3168) and DRG 694 (Urinary Stones without MCC, relative weight 0.7815), in MDC 11 (Diseases and Disorders of the Kidney and Urinary Tract), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about Suburethral calculus ICD-10 codes
What is the ICD-10 code for Suburethral calculus?
- N21.8 — Other lower urinary tract calculus.
Is N21.8 billable?
- Yes. N21.8 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can N21.8 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict N21.8 as a principal diagnosis.
Is N21.8 a CC or MCC?
- No. N21.8 is neither a CC nor an MCC under MS-DRG v44.0.