Exploring ICD-10-CM’s Chapter 20: External Causes of Morbidity

In a previous article titled ICD-10: the Axis of Classification, I discussed a particularly simple method for preparing your key stakeholders for the transition to ICD-10. The method consists of breaking ICD-10-CM down into its basic components: chapters and axes of classification. This article continues that theme in reviewing the third-largest chapter in ICD-10-CM: Chapter 20, “External Causes of Morbidity.” There is a supplemental classification in ICD-9-CM titled “External Causes of Injury & Poisoning.”

In the 2012 fiscal year version of ICD-9-CM, the code range for external causes is E000-E999, and this grouping consists of 1,291 codes. Compare this to the FY 2012 version of ICD-10-CM, where Chapter 20’s code range is V00-Y99 and consists of 7,518 codes. This comparison nets us an addition of 6,227 codes, or an increase of 482 percent. So in effect, our former E codes are now V, W, X, and Y codes. The new E codes in ICD-10-CM are found in Chapter 4 – titled “Endocrine, Nutritional & Metabolic Diseases” – and include the code range E00-E89.

Chapter 20 in ICD-10-CM contains nine percent of the total volume of available codes, again, ranking it third in terms of having the greatest number of total codes. Now that we have identified the content within this chapter, you likely are wondering “Why the significant increase?” The answer to that can be explained by reviewing the general changes that have occurred.

We start with noting that there are 33 subchapters used to report the cause/activity resulting in an injury or health condition, the intent (unintended/accidental/intentional; suicide or assault), the place where the event occurred, and the patient’s status at the time of the event (civilian, military, etc.). An external cause code is assigned for each encounter during which an injury or condition is treated — not just for the initial treatment. To accomplish this, three new seventh-character extensions were added to identify the episode of care for the current encounter. They include:

  • A: initial encounter
  • D: subsequent encounter
  • S: sequelae

The seventh character “A” is to be used for as long as the patient continues to receive active treatment (emergency department care, surgical treatment or evaluation and management by a new physician) of the external cause of morbidity. The seventh character “D” is used for encounters occurring after the patient has completed active treatment; this would include services such as a cast change or removal, an encounter for the removal of either an internal or external fixation device, medication adjustment, or other aftercare or follow-up visits. The seventh character “S” is used to report encounters for the care of a late effect, or sequela, for each intent code (accident, assault, suicide, etc.). These seventh-character extensions are a major contributor to the increased code volume in Chapter 20.

Other expansions in the axis of classification are attributed to increased specificity at the fourth, fifth and sixth character levels (for example, instead of a fall from playground equipment, you can capture a fall on or a fall from a playground slide, swing, jungle gym or other). For another example, there are 312 codes for injuries involving animals (there are only nine such codes in the international version). These include separate codes so specific they even can identify between "bitten by turtle" and "struck by turtle." The level of detail included here has attracted much attention on YouTube. Here are a few interesting examples, but if you would like to view more, go online and search for videos with the tagline "Yeah, there's a code for that."

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