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ICD-10-CM Coding Guidelines and Concepts — Medical Coder practice questions

19 multiple-choice questions and 8 flashcards on ICD-10-CM Coding Guidelines and Concepts, about 11% of the Medical Coder bank. Every one carries a written rationale.

Written and maintained by Nick Burton · last updated 2026-08-22 · how we write and review questions

What this chapter covers

ICD-10-CM Coding Guidelines and Concepts is one of 6 chapters in CoStudy's Medical Coder (CPC/AAPC) bank, and it holds 19 of the bank's 173 multiple-choice questions — roughly 11% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.

Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.

Free ICD-10-CM Coding Guidelines and Concepts practice questions

10 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.

NOS in ICD-10-CM means:

  1. Not Otherwise Specified — equivalent to 'unspecified'
  2. Not Our Service
  3. No Other Symptoms
  4. Negative Outcome Status

Answer: A — Not Otherwise Specified — equivalent to 'unspecified'

NOS = Not Otherwise Specified = unspecified. NEC = Not Elsewhere Classifiable = 'other specified.' Use specific codes when documentation supports.

Initial encounter for a closed fracture of the left distal radius — what 7th character?

  1. A
  2. B
  3. D
  4. S

Answer: A — A

7th character A = initial encounter for closed fracture. B = initial open. D = subsequent routine healing. S = sequela. Open vs closed determined by clinician documentation.

For an Excludes2 note, the coder may:

  1. Never code both
  2. Code both if both conditions are present
  3. Code only the parent
  4. Code only the excluded

Answer: B — Code both if both conditions are present

Excludes2 = 'not included here' but both conditions CAN be coded together if both are documented. Excludes1 is the absolute mutual-exclusion note.

Z codes describe:

  1. Specific diseases
  2. Factors influencing health status + contact with health services
  3. Procedures
  4. Drugs

Answer: B — Factors influencing health status + contact with health services

A/C/D) Wrong. B) Correct — routine exam, screening, status codes.

ICD-10-CM is used for:

  1. Procedures
  2. Diagnoses
  3. Supplies
  4. Drugs

Answer: B — Diagnoses

A) CPT. B) Correct. C/D) HCPCS Level II.

Z79.4 represents:

  1. Long-term (current) use of insulin
  2. Family history of diabetes
  3. Diabetic screening
  4. Routine exam

Answer: A — Long-term (current) use of insulin

Z79.4 = long-term (current) use of insulin. Status code. Frequently used adjunct to E11.x for type 2 DM on insulin.

A patient is documented with an adverse effect from a drug taken correctly as prescribed. This is coded using:

  1. A poisoning code (T36-T50) with the appropriate 6th/7th character
  2. The code for the nature of the adverse effect (e.g., the reaction) plus the drug code from Table of Drugs and Chemicals with an 'adverse effect' 5th/6th character
  3. An underdosing code
  4. An external cause code only, with no drug code

Answer: B — The code for the nature of the adverse effect (e.g., the reaction) plus the drug code from Table of Drugs and Chemicals with an 'adverse effect' 5th/6th character

A) Poisoning codes apply when the drug was taken incorrectly, in excess, or was not prescribed for the patient — not when taken correctly. B) Correct — code the nature of the reaction first, then the drug code with the adverse-effect character from the Table of Drugs and Chemicals. C) Underdosing applies when LESS medication than prescribed was taken. D) A drug code is required, not omitted.

Excludes1 note means:

  1. Examples
  2. Conditions never coded together
  3. Coded together OK
  4. Optional

Answer: B — Conditions never coded together

A) Includes. B) Correct — 'not coded here.' C) Excludes2.

When a patient is admitted for treatment of a primary malignancy and, during that same encounter, a secondary (metastatic) site is also treated, which is sequenced first?

  1. The metastatic site code, always
  2. Neither is sequenced first; both are listed alphabetically
  3. The code for the neoplasm responsible for the treatment provided during the encounter is sequenced first
  4. The metastatic site is never coded

Answer: C — The code for the neoplasm responsible for the treatment provided during the encounter is sequenced first

A) Not a universal rule — depends on which site the encounter's treatment targets. B) ICD-10-CM sequencing is guideline-driven, not alphabetical. C) Correct — sequencing follows which neoplasm (primary or secondary) the encounter's treatment is directed at; that code is listed first. D) Metastatic sites get their own codes (C77-C79) when documented.

A combination code in ICD-10-CM is:

  1. A code that requires two separate codes to be billed together
  2. A single code that classifies two diagnoses, a diagnosis with an associated secondary process, or a diagnosis with an associated complication
  3. A code only used for external causes
  4. A code that is always an 'unspecified' code

Answer: B — A single code that classifies two diagnoses, a diagnosis with an associated secondary process, or a diagnosis with an associated complication

A) Combination codes replace the need for two codes with one — the opposite of what's stated. B) Correct — e.g., E11.21 combines type 2 diabetes with diabetic nephropathy into a single code. C) Not limited to external causes. D) Combination codes are typically specific, not unspecified.

ICD-10-CM Coding Guidelines and Concepts flashcards

1 cards from the 8 in this chapter.

ICD-10-CM?

International Classification of Diseases, 10th edition, Clinical Modification. Used in US for diagnoses. 3-7 character alphanumeric codes. Replaced ICD-9 in October 2015.

Practise the full chapter

These are a sample. The full ICD-10-CM Coding Guidelines and Concepts chapter runs 27 items with per-chapter progress tracking, on the web and in the iOS app.

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