ICD-10-CM Coding Tips Every Medical Practice Should Know

ICD-10-CM has over 70,000 diagnosis codes. The difference between a correct code and a rejected claim often comes down to specificity. These tips help practices code more accurately and get claims paid the first time.

1. Always Code to the Highest Specificity

ICD-10-CM rewards specificity. "Diabetes mellitus" doesn't cut it — you need to specify the type, whether there are complications, and the nature of any complications. Payers are increasingly denying claims coded at a nonspecific level when a more specific code exists.

2. Always Include Laterality

When a code has left/right/bilateral options, always use the specific laterality. Coding "rotator cuff tear" without specifying left or right (when the codes exist for each) will cause rejections from increasingly strict payer edits.

3. Sequence Codes in the Correct Order

The principal/first-listed diagnosis should be the main reason for the encounter. Secondary codes follow. Common sequencing errors:

• Listing symptom codes instead of the confirmed diagnosis
• Putting chronic conditions first when the visit is for an acute problem
• Not sequencing combination codes correctly (e.g., CHF with hypertension)

4. Don't Code Signs and Symptoms When a Definitive Diagnosis Is Available

If the physician has documented a definitive diagnosis, don't code the presenting symptoms separately (unless they're not routinely associated with the condition). For example, if the diagnosis is pneumonia, don't also code cough and fever — they're integral to the diagnosis.

5. Use Z Codes Appropriately for Preventive and Screening Visits

Many practices under-utilize Z codes for wellness visits, screenings, immunizations, and encounters for factors influencing health status. These codes support medical necessity for preventive services and are critical for avoiding denial of routine care.

6. Stay Current on Annual Code Updates

ICD-10-CM updates take effect October 1 each year. New codes are added, old ones revised or deleted. Using deleted codes results in immediate rejections. Subscribe to CMS update notifications and review code change summaries each September.

7. Use the Official Coding Guidelines

ICD-10-CM includes official Coding Guidelines published annually by CMS and the NCHS. Many coding disputes come down to ignoring these guidelines. Always reference them for complex cases, especially trauma, pregnancy, and inpatient records.