In recent years there has been a big push, for both coders and providers, towards coding to the highest specificity. Especially since the release of ICD-10-CM. That said, there are still no national guidelines for mandatory reporting for the codes of Chapter 20: External Causes of Morbidity. The exception to this are providers who are required by a particular payer, or a state-based mandate. As such, it’s important to stay informed on what is required for reporting for your provider(s). However, best practices suggest we voluntarily report, follow ICD-10-CM guidelines, and code the highest specificity known.
Before we dive in, remember: external causes of morbidity codes are never to be coded as the primary or principle diagnosis. These unique codes within chapter twenty are always to be used as secondary codes to provide supplementary data on injuries and other health conditions captured within the health record. This data can then be used for injury research, evaluation of injury prevention, and can also be used by payers.
General Guidelines and Examples
The codes can be used with any code within the following ranges that an external cause code is applicable to: A00.0-T88.9 and Z00-Z99. Primarily, external cause codes are used with injury codes, but there are instances that it would be appropriate to further specify the cause. For instance, a heart attack due to strenuous activity, or signs and symptoms such as shoulder pain from a ground level fall.
Guidelines state it would be inappropriate to code an external cause for codes that already include the cause within the code description.
As an example, let’s take a look at a code from the poisonings section: T45.511 Poisoning by anticoagulants, accidental (unintentional). Even though this code falls into the code range stated above, it would be incorrect to assign an external cause, as the intent/cause is already reported within the description.
Activity and Place of Occurrence codes are only reported once during the initial encounter, unless a new injury occurs while hospitalized. It is important to note that both Y92.9 Unspecified Place or Not Applicable and Y93.9 Activity, Unspecified are never to be used if the place or activity are not stated. When reporting external cause codes, there should be one place of occurrence, one activity, and one status code, unless there is a new injury. However, it is possible to report more than one external cause code in order to accurately report how the injury happened.
An external cause status code should be assigned whenever an external cause code is assigned. Only one status code may be reported at the initial encounter and, just like the Activity and Place of Occurrence codes, Y99.9 Unspecified External Cause status should not be reported if it is not stated within the record. Also, never assign a status code if there are no reportable external cause codes, such as with poisonings.
Example: A 41-year-old male came into the ER with his spouse. He states he fell off a ladder while volunteering at a nursing home, and reports left ankle pain. After workup, the provider determines there are no signs of a fracture, and diagnoses a left ankle sprain.
The codes we report are:
S93.402A Sprain of Unspecified Ligament of Left Ankle, initial encounter
W11.XXA Fall On and From Ladder, initial encounter
Y92.129 Unspecified Place in Nursing Home as the place of occurrence of the external cause
Y99.2 Volunteer Activity
In the example above, no activity was reported for the patient during the injury, we do not assign Y93.9 Activity, Unspecified. Keep in mind that if the medical record documentation had not stated that the patient was volunteering or specified the place, we would not have assigned the unspecified codes and only the fall from the ladder would be reported as an additional code.
Sequencing Multiple External Causes
When multiple injuries are caused by different reasons, ICD-10-CM Guidelines clarify what order or priority the external causes should be reported, as follows:
Child and adult abuse, then terrorism events, followed by cataclysmic events, then, lastly, transport accidents.
In child and adult abuse cases, assault codes are used to report any injuries in confirmed cases. If the perpetrator is known, also report a code from category Y07 Perpetrator of Maltreatment and Neglect.
Sequelae External Cause Codes
Sequelae codes are used to report late effects of an injury for as long as they are present or are being treated. When determining if a sequelae code should be reported, keep in mind that a sequela, or late effect, is not the same as a healing injury. A healing injury should be reported with the seventh character “A” or “D” as appropriate for follow-up care.
Code category Y38, Terrorism is only reported when the cause of the stated injury is reported as such by the Federal Bureau of Investigation (FBI). If the event or cause is not reported by the FBI as terrorism, or it is suspected, it is then classified as an assault. Additionally, more than one code may be assigned from this category in the scenario that the injury or injuries resulted from multiple mechanisms of terrorism.
When coding and reporting from Chapter 20, a comprehensive review of the guidelines and conventions are necessary to ensure accurate code assignment. Working with external cause codes is unique, as far as the separate External Causes Index along with some interesting codes found within the Tabular List of Diseases and Injures. I recommended you take the time to familiarize yourself with the variety of codes found within this chapter and, as always, stay informed on the yearly updates to codes and guidelines.