CCS (AHIMA) cheat sheet

ICD-10-PCS codes are exactly 7 alphanumeric characters; each character position is a defined axis (section, body system, root operation, body part, approach, device, qualifier) read in that fixed order.

ICD-10-CM codes are 3-7 characters: character 1 is alphabetic (U reserved), character 2 is always numeric, and characters 3-7 may be alpha or numeric.

Principal diagnosis (inpatient) = the condition established after study as chiefly responsible for the admission; first-listed diagnosis (outpatient) = the condition documented as the reason for the encounter.

Root operation distinction: Resection removes all of a body part; Excision removes some or all of a body part without replacement; Detachment cuts off all or a portion without going through a joint.

CPT Category I codes are 5 digits; Category II are 4 digits plus F (performance measurement); Category III are 4 digits plus T (temporary/emerging technology).

HCPCS Level II codes are 5 characters beginning with a letter A-V and cover supplies, drugs, and services not represented in CPT.

Modifier 25 reports a significant, separately identifiable E/M service by the same provider on the same day as a procedure or other service.

Modifier 59 or the X{EPSU} subset reports distinct procedural service; use only when no more specific modifier (51, 58, RT/LT, etc.) describes the circumstance.

Codes requiring a 7th character need the correct encounter value: A initial, D subsequent, S sequela; the 7th character must be applied to every code in the injury/external cause cluster.

Medical necessity and code assignment rest on the provider's documented assessment; a coder may not infer a diagnosis, condition, or cause-and-effect relationship that the provider did not state.

CMS Conditions of Participation require the history and physical no more than 30 days before admission, updated within 24 hours after inpatient admission.

Diagnoses must be documented by a provider authorized by medical staff bylaws; nursing notes, discharge instructions, and ancillary staff entries cannot by themselves support a diagnosis code.

Amendments and late entries must be labeled as such, dated and timed when written, authenticated by the authoring provider, and must not obscure the original content.

Verbal and telephone orders require authentication by the responsible provider within the timeframe set by state law and medical staff policy.

Cloned or copy-pasted documentation must be verified against that patient's actual clinical course; unverified text cannot support a code.

Each code must be supported by documentation present in the record at the time of coding; documentation added only to justify a code is not acceptable.

The discharge summary should reconcile the reason for admission, hospital course, procedures performed, and final diagnoses so that coding reflects the full episode.

A compliant query states the clinical indicators found in the record, asks one clear question, and offers multiple-choice options that include 'other' or 'unable to determine'.

Queries must be non-leading: present the evidence and ask for clarification rather than naming the diagnosis the coder expects or wants.

Open-ended queries ('please clarify' or 'please specify') let the provider supply the diagnosis in their own words and carry the lowest risk of leading.

Closed multiple-choice queries are acceptable when each option is supported by clinical indicators documented in the record.

A query must be triggered by documentation ambiguity, conflict, or lack of specificity, never solely by a desire to change payment or the DRG.

The query and the provider's response are part of the legal health record and must be retained and retrievable under the organization's retention policy.

If the provider does not respond, assign only the codes supported by existing documentation; do not assume the queried condition.

Common query triggers: clinical indicators with no diagnosis, conflicting diagnoses, unclear etiology, and unspecified diagnoses where the record holds detail supporting greater specificity.

HIPAA Privacy Rule minimum necessary standard limits uses and disclosures of protected health information to the least amount reasonably needed for the purpose.

Breach notification: notify affected individuals without unreasonable delay and no later than 60 days after discovery; breaches affecting 500 or more individuals also require prompt HHS notice.

NCCI procedure-to-procedure edits pair a Column One (payable) code with a Column Two (bundled) code; a modifier may override only when the clinical circumstances meet that modifier's definition.

National Coverage Determinations are issued by CMS and bind all Medicare contractors; Local Coverage Determinations are issued by a Medicare Administrative Contractor and bind only its jurisdiction.

Recovery Audit Contractors may review Medicare claims up to 3 years from the date of payment to identify overpayments and underpayments.

False Claims Act liability includes three times the government's damages plus civil monetary penalties for each false claim knowingly submitted.

The seven OIG compliance program elements: written policies, compliance officer and committee, training, communication lines, internal monitoring and auditing, enforcement and discipline, corrective action.

Two-midnight rule: inpatient admission is generally appropriate when the physician expects the beneficiary to require hospital care spanning at least two midnights.

Medical necessity requires services be reasonable and necessary for diagnosis or treatment, and the diagnosis code on the claim must be supported by the record.

The MS-DRG grouper assigns a DRG from the principal diagnosis, secondary diagnoses acting as CC or MCC, procedures performed, age, sex, and discharge disposition.

CC/MCC exclusion lists determine whether a secondary diagnosis is eligible to function as a complication or comorbidity for the assigned DRG.

Computer-assisted coding applies natural language processing to suggest codes from documentation; a credentialed coder must validate every suggestion before final assignment.

Encoders apply NCCI edits, medical-necessity edits, and age/sex conflict checks at the point of code entry.

HL7 version 2 messages and FHIR resources are the common standards for exchanging clinical data between EHR systems and ancillary applications.

SNOMED CT is a clinical terminology used to capture findings in the record; ICD-10-CM/PCS are classifications used for reporting and reimbursement.

The HIPAA Security Rule requires a documented risk analysis, unique user identification, and audit controls; encryption is an addressable implementation specification.

Downtime and disaster recovery procedures must define how code assignment, data capture, and record retrieval continue when the EHR or encoder is unavailable.