Medical Coding Overview: ICD Part 1
Introduction to the International Classification of Diseases (ICD) coding system and its role in healthcare billing.
📘 Reading Lesson
Lesson Notes
Read through the key concepts before you try the challenge.
What Is ICD Coding?
ICD stands for International Classification of Diseases. It is the global standard for classifying diagnoses, symptoms, and health conditions. In the United States, ICD-10-CM is used for outpatient and physician billing.
- ICD-10-CM: Clinical Modification — used by providers to code diagnoses
- ICD-10-PCS: Procedure Coding System — used in inpatient hospital settings
- Codes are alphanumeric (e.g., J18.9 = Pneumonia, unspecified)
Why Accurate ICD Coding Matters
ICD codes are used on every insurance claim. An inaccurate code can cause a claim to be rejected, underpaid, or flagged for audit. Coders must select the most specific code that is supported by documentation.
The rule in coding: if it isn't documented, it didn't happen. Coders cannot assign a code for a condition that the provider did not document in the patient record.
Challenge
Apply what you've learned in this lesson.