In ICD-9-CM, a code starting with the letter E indicates which of the following?

• A. External causes of injury
• B. There is no specific code in the classification system
• C. Type of examination
• D. Echovirus

Answer: (A)

Codes that begin with E in ICD-9-CM are used to capture external causes of injury and other adverse events. These E codes are added to the main diagnosis to tell how the injury or event occurred—such as a fall, a vehicle crash, or exposure to a poison—rather than describing the disease itself. They help describe the circumstances of the injury for public health tracking. The other options don’t fit: a code for the type of examination isn’t indicated by an E prefix, and an echovirus would be coded with a numeric disease code rather than starting with E. Therefore, an E-prefixed code identifies external causes of injury.