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CPC - ICD-10-CM and HCPCS Level II Coding - Section 4.1

Assign ICD-10-CM diagnosis codes to the highest level of specificity, applying the Official Guidelines for Coding and Reporting, including laterality, episode of care, and combination codes.

Code diagnoses from the documentation using the ICD-10-CM Alphabetic Index and Tabular List, coding to the highest level of specificity with the required seventh character for episode of care and the correct laterality. Apply the Official Guidelines for combination codes, manifestation pairs coded in the underlying-condition-first order, and the sequencing of a principal or first-listed diagnosis.

ICD-10-CM Official GuidelinesSeventh characterLateralityCombination codes

Practice question for this objective

Free sampleICD-10-CM and HCPCS Level II Codinghard

A seventh character is required for many injury and fracture codes in Chapter 19, but the base code contains fewer than six characters. According to the ICD-10-CM conventions, how is the seventh character placed so that the code is valid?

  • AThe seventh character is simply appended after the last populated character, and any shorter code is left as is because trailing spaces are ignored.
  • BThe placeholder X is used to fill each empty character position so that the seventh character lands in the seventh position of the code. Correct
  • CThe coder assigns the shortest valid code available and omits the seventh character whenever the base code is shorter than six characters.
  • DA zero is inserted in each empty position because zero is the neutral filler defined by the Tabular List for incomplete codes.
The placeholder X fills empty character positions so a required seventh character occupies the true seventh position. ICD-10-CM uses the letter X as a dummy placeholder to hold empty character positions in codes that require a seventh character but are shorter than seven characters. This keeps the seventh character in its correct position and the code valid for submission.

Why A is wrong: This produces an invalid code. The seventh character must occupy the seventh position exactly, so appending it directly to a shorter code places it in the wrong slot and the code will not process.

Why B is correct: This is the correct use of the dummy placeholder X. When a code needs a seventh character but has empty positions before it, X fills those positions so the seventh character sits in the true seventh slot.

Why C is wrong: Omitting a required seventh character makes the code invalid. The requirement to code to the highest specificity means the seventh character cannot be dropped merely because the base code is short.

Why D is wrong: Zero is a meaningful character in ICD-10-CM, not a filler. The classification defines X, not 0, as the placeholder, so using zero would change the code's meaning rather than pad it.

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