What Is ICD-10-CM?
ICD-10-CM is the U.S. clinical modification of the WHO's ICD-10 diagnosis code set, maintained by the CDC's National Center for Health Statistics, used to report diagnoses on all HIPAA-covered claims.
- Code to the highest level of specificity supported by documentation — using unspecified codes when a specific code exists is a top denial driver and audit finding.
- Laterality (right/left), encounter type (initial/subsequent/sequela), and severity must all be documented to support specific codes.
ICD-10-CM
Also known as: International Classification of Diseases, Tenth Revision, Clinical Modification; ICD-10
ICD-10-CM is the U.S. clinical modification of the WHO's ICD-10 diagnosis code set, maintained by the CDC's National Center for Health Statistics, used to report diagnoses on all HIPAA-covered claims.
Definition
ICD-10-CM contains roughly 70,000 alphanumeric diagnosis codes (3-7 characters) replacing ICD-9-CM as of October 1, 2015. The first three characters represent the category (e.g., E11 = Type 2 diabetes mellitus); subsequent characters add etiology, anatomic site, severity, laterality, and encounter type. ICD-10-CM is updated annually with new codes effective October 1. CMS and the CDC's NCHS jointly maintain the system. Coding follows the ICD-10-CM Official Guidelines for Coding and Reporting.
Example
E11.9 = Type 2 diabetes mellitus without complications. M17.11 = Unilateral primary osteoarthritis, right knee. S52.501A = Unspecified fracture of the lower end of right radius, initial encounter for closed fracture. The seventh character A/D/S distinguishes initial vs subsequent vs sequela encounters.
Common Misconceptions
ICD-10-CM is not the same as ICD-10-PCS. ICD-10-CM is for diagnoses (used on every claim type — physician, outpatient, inpatient). ICD-10-PCS is only for inpatient hospital procedures. Outpatient procedures use CPT/HCPCS, not ICD-10-PCS.
Practical Application
Code to the highest level of specificity supported by documentation — using unspecified codes when a specific code exists is a top denial driver and audit finding. Laterality (right/left), encounter type (initial/subsequent/sequela), and severity must all be documented to support specific codes.
Related Terms
CPT (Current Procedural Terminology)
CPT is the five-digit procedural code set developed and maintained by the American Medical Association that describes medical, surgical, and diagnostic services performed by physicians and qualified health professionals; it is HIPAA-named for use in claims.
Read definitionICD-10-PCS
ICD-10-PCS is the U.S. inpatient hospital procedural code set maintained by CMS, with seven-character alphanumeric codes used exclusively to report procedures performed during inpatient hospital admissions for billing under MS-DRGs.
Read definitionDRG (Diagnosis-Related Group)
A DRG is the inpatient hospital classification system that groups admissions with similar clinical characteristics and resource use into a single payment category; CMS uses MS-DRGs to pay hospitals under the IPPS for Medicare inpatient stays.
Read definitionNCCI (National Correct Coding Initiative)
NCCI is a CMS-published set of edits that prevent improper payment when incorrect code combinations or unit counts are submitted. The program contains three edit types: Procedure-to-Procedure (PTP) edits, Medically Unlikely Edits (MUE) limiting units of service, and Add-on Code edits.
Read definitionWhere This Applies on MedPrecision
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