ICD-10-CM Diagnosis Coding
Diagnosis coding · Beginner · 3 lessons
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Code structure, index & tabular workflow
14 min read
ICD-10-CM codes are 3–7 alphanumeric characters. Character 1 is alphabetic, character 2 is numeric, characters 3–7 may be alpha or numeric. The first three characters are the category, characters 4–6 add etiology, anatomic site, laterality and severity, and character 7 is an extension used mainly in Chapters 15 (obstetrics), 19 (injury/poisoning) and 20. A decimal point follows the third character. Coding always starts in the Alphabetic Index and is never final until verified in the Tabular List.
- ✓Never code directly from the Alphabetic Index — locate the main term, read subterms, then verify in the Tabular List.
- ✓Placeholder 'X' fills empty character positions so a required 7th character stays in position 7 (e.g., T15.02XA).
- ✓7th characters in Chapter 19: A = initial encounter (active treatment), D = subsequent encounter (healing/recovery), S = sequela (late effect).
- ✓Laterality: 1 = right, 2 = left, 3 = bilateral (when the code offers it); 9 = unspecified side.
- ✓Code to the highest level of specificity supported by the documentation — an unspecified code is only correct when the record truly lacks the detail.
Flashcards
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Case studies
Apply the guidelines to real documentation
Sequencing a manifestation
Office note: 'Type 2 diabetes mellitus with diabetic polyneuropathy, stable on metformin. Also long-term insulin use.'
How is this reported?
Knowledge check
4 questions
1. A patient returns for routine healing follow-up of a closed fracture of the right radial shaft. Which 7th character applies?
2. Code T15.02X_ requires a 7th character. Why is the X present?
3. Which statement about Excludes notes is correct?
4. Documentation states 'chest pain, rule out myocardial infarction' in the physician office. What is coded?