Coding Knowledge and Skills
Coding Knowledge and Skills is the largest content area on the CCA exam. The questions test whether you can select the right code, sequence it correctly, and justify the choice from the documentation using ICD-10-CM, ICD-10-PCS, CPT, and HCPCS Level II - not whether you have memorized a code book.
Know which system answers which question
ICD-10-CM classifies diagnoses, signs and symptoms, and reasons for encounters (Z codes). Many codes run to seven characters, using laterality and a seventh character for episode of care (A initial, D subsequent, S sequela) in injury codes. ICD-10-PCS reports inpatient procedures only, always seven alphanumeric characters with no decimal point, and every character position has a fixed meaning: section, body system, root operation, body part, approach, device, qualifier. CPT describes physician and outpatient services across six sections, and HCPCS Level II adds supplies, drugs (J codes), durable medical equipment (E), orthotics and prosthetics (L), temporary (Q) codes, and the Medicare liability modifiers GA, GZ, GY, and KX.
Conventions that decide sequencing
- Read the tabular notes: code first tells you which condition is principal; use additional code tells you a second code is required.
- Excludes1 means the two codes may never be reported together. Excludes2 means not included here - report both when both conditions are documented and treated.
- Combination codes capture two elements in one code, such as E11.22 for type 2 diabetes with diabetic chronic kidney disease.
- For sequelae, code the residual condition first and the causal condition second.
- Query the provider when the record is ambiguous, incomplete, or contradictory. Never infer a diagnosis from a medication or a lab value.
Modifiers and edits
Modifier 25 marks a significant, separately identifiable E/M service on the same day as a procedure. Modifiers 26 and TC split professional and technical components. Modifier 59, or the more specific X{EPSU} modifiers, identifies a distinct service but must never be used to bypass an NCCI procedure-to-procedure edit that the documentation does not support.
Worked example
An inpatient note reads: type 2 diabetes mellitus with diabetic chronic kidney disease, stage 3a. The combination code E11.22 captures the diabetes-to-kidney link, so the stage still requires its own code, N18.31. Sequence E11.22 first, then N18.31, after confirming both conditions were evaluated and treated rather than copied forward from the problem list.
Traps that cost marks
Coding from the problem list or an old history instead of the current note; treating history of as an active condition; reporting CPT for an inpatient procedure; unbundling components that the code already includes; omitting laterality or the seventh character; and coding a rule-out diagnosis as confirmed in the outpatient setting.