CCA – Certified Coding Associate

Inpatient coding assigns diagnosis and procedure codes for patients formally admitted to a hospital by a physician's order. ICD-10-CM reports diagnoses and ICD-10-PCS reports procedures. Inpatient codes drive MS-DRG assignment, quality reporting, and healthcare statistics, so the rules for selecting the principal diagnosis and reporting additional diagnoses are tested heavily.

The International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) is the HIPAA-mandated code set for reporting diagnoses in every U.S. healthcare setting. It contains more than 70,000 codes organized into 22 chapters by body system or etiology. Codes are alphanumeric and three to seven characters long: the first character is a letter, the second is a number, and the third may be a number or a letter (for example, C7A). A decimal point follows the third character.

Appendix I contains the present on admission (POA) reporting guidelines. The guidelines are a HIPAA-required companion to the code set; adherence is required when assigning ICD-10-CM codes.

Coding begins in the Alphabetic Index, where main terms (conditions, injuries, eponyms) are listed with indented subterms. The code is then verified in the Tabular List, which arranges codes in categories, subcategories, and codes and contains the instructional notes that must be followed. Never assign a code from the Index alone.

The Uniform Hospital Discharge Data Set (UHDDS) defines the principal diagnosis as "that condition established after study to be chiefly responsible for occasioning the admission of the patient to the hospital for care." The phrase after study means the coder looks at the whole stay, not just the admitting diagnosis.

UHDDS defines other diagnoses as conditions that coexist at admission or develop subsequently and affect patient care. Report a secondary condition when it requires at least one of the following:

• Clinical evaluation
• Therapeutic treatment
• Diagnostic procedures
• Extended length of hospital stay
• Increased nursing care and/or monitoring

Do not code conditions from a previous admission that no longer affect care, but history codes (Z85–Z87) and status codes may be reported when they influence current care. Abnormal findings (laboratory, X-ray, pathology) are not coded unless the provider indicates their clinical significance. When a condition has both acute and chronic forms with separate codes and no combination code, code both and sequence the acute code first.

ICD-10-PCS reports procedures performed in the hospital inpatient setting. It contains roughly 79,000 codes, each exactly seven alphanumeric characters long. The letters O and I are never used, so they cannot be confused with zero and one. Codes are built from the PCS Tables, where every character value must come from the same table row.

The root operation (character 3) describes the objective of the procedure. The Medical and Surgical section uses 31 root operations. Choosing the root operation that matches the documented objective is the most frequently tested PCS skill.

POA reporting is required for all diagnosis codes on inpatient claims for acute care hospitals. Medicare does not pay the higher DRG for certain hospital-acquired conditions (HACs), such as catheter-associated urinary tract infections and stage 3 or 4 pressure ulcers, when the condition is reported with POA indicator N or U.

A comorbidity is a pre-existing condition that affects treatment; a complication arises during the stay. CMS designates certain secondary diagnoses as CCs or MCCs because they increase resource use. Reporting a documented CC or MCC can move a case to a higher-weighted MS-DRG. A CC or MCC does not count when it appears on the CC exclusion list for the principal diagnosis.