ICD-10-CM Code Structure
ICD-10-CM (Clinical Modification) is used for diagnosis coding in all healthcare settings. Codes are alphanumeric and range from 3 to 7 characters in length.
| Position | Description | Example (S52.501A) |
|---|---|---|
| 1 | Category (alpha) | S - Injury |
| 2-3 | Category (numeric) | 52 - Fracture of forearm |
| 4 | Subcategory (after decimal) | 5 - Lower end of radius |
| 5 | Subcategory detail | 0 - Unspecified fracture |
| 6 | Further specificity | 1 - Right side |
| 7 | Extension | A - Initial encounter |
ICD-10-CM Chapter Overview
ICD-10-CM contains 21 chapters organized by body system or condition type. Key chapters include:
- Chapter 1 (A00-B99): Certain infectious and parasitic diseases
- Chapter 2 (C00-D49): Neoplasms
- Chapter 9 (I00-I99): Diseases of the circulatory system
- Chapter 10 (J00-J99): Diseases of the respiratory system
- Chapter 19 (S00-T88): Injury, poisoning, and certain other consequences of external causes
- Chapter 20 (V00-Y99): External causes of morbidity
- Chapter 21 (Z00-Z99): Factors influencing health status and contact with health services
Key ICD-10-CM Conventions
- Includes notes: Define or clarify content of a category
- Excludes1: "Not coded here" - codes are mutually exclusive and should never be used together
- Excludes2: "Not included here" - the excluded condition is not part of the category but a patient may have both conditions simultaneously
- Code first / Use additional code: Indicates sequencing and the need for multiple codes
- Placeholder "x": Used to hold a position when a 7th character extension is required but fewer than 6 characters precede it
- 7th character extensions: A (initial encounter), D (subsequent encounter), S (sequela)
ICD-10-PCS Code Structure
ICD-10-PCS (Procedure Coding System) is used exclusively for inpatient hospital procedures. Every code is exactly 7 alphanumeric characters.
| Position | Meaning (Medical/Surgical) |
|---|---|
| 1 | Section (e.g., 0 = Medical and Surgical) |
| 2 | Body System |
| 3 | Root Operation |
| 4 | Body Part |
| 5 | Approach |
| 6 | Device |
| 7 | Qualifier |
Common ICD-10-PCS Root Operations
| Root Operation | Value | Definition | Example |
|---|---|---|---|
| Excision | B | Cutting out or off without replacement a portion of a body part | Partial nephrectomy |
| Resection | T | Cutting out or off without replacement all of a body part | Total nephrectomy |
| Replacement | R | Putting in a biological or synthetic substitute | Total hip replacement |
| Repair | Q | Restoring a body part to its normal structure (not elsewhere classified) | Hernia repair (suture) |
| Bypass | 1 | Altering the route of passage of body contents | CABG |
| Drainage | 9 | Taking or letting out fluids and/or gases | Thoracentesis |
| Extraction | D | Pulling or stripping out or off all or a portion of a body part by force | Bone marrow biopsy |
| Inspection | J | Visually and/or manually exploring a body part | Diagnostic arthroscopy |
| Transplantation | Y | Putting in all or a portion of a living body part from another individual | Kidney transplant |
ICD-10-PCS Approaches
- Open (0): Cutting through skin or mucous membrane and any other body layers to reach the operative site
- Percutaneous (3): Entry by puncture or minor incision, without visualization
- Percutaneous Endoscopic (4): Entry by puncture or minor incision with endoscopic visualization
- Via Natural or Artificial Opening (7): Entry through a natural or artificial external opening
- Via Natural or Artificial Opening Endoscopic (8): Entry through a natural or artificial opening with endoscopic visualization
- External (X): Procedures performed directly on the skin or mucous membrane
Key Coding Guidelines to Remember
- Code the principal diagnosis as the condition established after study to be chiefly responsible for the admission
- Code all documented conditions that affect patient care (treatment, diagnostic workup, extended LOS, or increased nursing care)
- Do not code conditions that are rule-out, probable, or suspected for outpatient encounters - code signs and symptoms instead
- For inpatient encounters, code conditions described as probable, suspected, likely, or rule-out as if confirmed
- Assign the most specific code available - never use an unspecified code when a more specific code is supported by documentation