Even experienced medical coders make errors that result in claim denials, delayed payments, and compliance issues. Understanding the most common ICD-10 coding mistakes—and how they violate official ICD-10 coding guidelines—is the first step toward preventing them. Here are the top 10 errors we see and how to avoid them.
1. Using Unspecified Codes When Specific Codes Exist
One of the most common errors is defaulting to unspecified codes when documentation supports more specific options. This can trigger audits and may result in lower reimbursement.
Solution: Always review documentation thoroughly and code to the highest specificity available.
2. Incorrect Sequencing (Code First Violations)
Failing to follow the Code First rule by listing manifestation codes before their underlying conditions.
Solution: Check all codes for "Code first" instructions and ensure proper sequencing.
3. Missing Laterality
Omitting laterality (right, left, bilateral) when it's documented and a specific code exists.
Solution: Query providers when laterality isn't documented but is needed for the code.
4. Excludes1 Violations
Coding two conditions together that have an Excludes1 relationship.
Solution: Always check Excludes notes and use validation tools to catch conflicts.
5. Gender Conflicts
Assigning gender-specific codes to patients of the wrong sex, such as prostate conditions for female patients.
Solution: Implement automated gender validation in your workflow.
Catch These Errors Automatically
Our Code Auditor detects all these common mistakes before submission.
6. Active vs History Conflicts
Coding both an active condition and history of that same condition in the same encounter.
Solution: Review active vs history guidelines and validate code sets.
7. Missing Additional Codes
Ignoring "Use additional code" instructions that require secondary codes for complete documentation.
Solution: Follow Use Additional Code instructions carefully.
8. Not Using Combination Codes
Using multiple codes when a single combination code captures the same information.
Solution: Search the Alphabetic Index for combination code options.
9. Coding from Claims Instead of Documentation
Using codes from previous claims rather than coding based on current documentation.
Solution: Always code from the current medical record documentation.
10. Using Outdated Code Books
Assigning codes that have been deleted or modified in the current year's update.
Solution: Stay current with annual ICD-10 updates and use current reference materials.
Prevention Strategy
The most effective way to prevent these errors is to implement automated validation tools that check codes before submission. Manual review catches some errors, but automated tools can check hundreds of rules consistently.