Coding Injuries in ICD-10-CM (update)

By Ann Zeisset, RHIT, CCS, CCS-P

ICD-10-CM provides greater specificity in coding injuries than ICD-9-CM. While many of the coding guidelines for injuries remain the same as ICD-9-CM, ICD-10-CM does include some new features, such as seventh characters.

Chapter 19 Overview

Chapter 19 is titled "Injury, Poisoning, and Certain Other Consequences of External Causes (S00–T88)." It encompasses two alpha characters. The S section provides codes for the various types of injuries related to single body regions; the T section covers injuries to unspecified body regions as well as poisonings and certain other consequences of external causes.

The following coding guidance is provided at the beginning of the chapter, "Use secondary code(s) from chapter 20, External Causes of Morbidity, to indicate cause of injury." Codes within the T section that include the external cause do not require an additional external cause code. The Official Coding Guidelines clarified the use of external cause codes in 2014. The guidelines state: “There is no national requirement for mandatory ICD-10-CM external cause code reporting. Unless a provider is subject to a state-based external cause code reporting mandate or these codes are required by a particular payer, reporting of ICD-10-CM codes in Chapter 20, External Causes of Morbidity, is not required. In the absence of a mandatory reporting requirement, providers are encouraged to voluntarily report external cause codes, as they provide valuable data for injury research and evaluation of injury prevention strategies.”

In ICD-10-CM, injuries are grouped by body part rather than by category, so all injuries of a specific site (such as head and neck) are grouped together rather than groupings of all fractures or all open wounds. Categories grouped by injury in ICD-9-CM such as fractures (800–829), dislocations (830–839), and sprains and strains (840–848) are grouped in ICD-10-CM by site, such as injuries to the head (S00–S09), injuries to the neck (S10–S19), and injuries to the thorax (S20–S29).

Injury Seventh Characters

Most categories in chapter 19 have seventh characters that are required for each applicable code, and most categories have the following choices (seventh characters for fractures are expanded):

  • A, Initial encounter
  • D, Subsequent encounter
  • S, Sequela

While the patient may be seen by a new or different provider over the course of treatment for an injury, assignment of the seventh character is based on whether the patient is undergoing active treatment and not whether the provider is seeing the patient for the first time.

For complication codes, active treatment refers to treatment for the condition described by the code, even though it may be related to an earlier precipitating problem. For example, code T84.50XA, Infection and inflammatory reaction due to unspecified internal joint prosthesis, initial encounter, is used when active treatment is provided for the infection, even though the condition relates to the prosthetic device, implant or graft that was placed at a previous encounter.

Initial encounter (A) is used while the patient is receiving active treatment for the injury (e.g., surgical treatment, emergency department encounter, and evaluation and continuing treatment by the same or a different physician). The appropriate seventh character for initial encounter should also be assigned for a patient who delayed seeking treatment for the fracture or nonunion.

Subsequent encounter (D) is used for encounters after the patient has received active treatment of the injury and is receiving routine care for the injury during the healing or recovery phase (e.g., cast change or removal, an x-ray to check healing status of fracture, removal of external or internal fixation device, medication adjustment, other aftercare and follow-up visits following injury treatment).

Sequela (S) is used for complications or conditions that arise as a direct result of an injury, such as scar formation after a burn. The scars are sequela of the burn. When using seventh character S, it is necessary to use both the injury code that precipitated the sequela and the code for the sequela itself. The S is added only to the injury code, not the sequela code.

The S seventh character identifies the injury responsible for the sequela. The specific type of sequela (e.g., scar) is sequenced first, followed by the injury code. Sequela is the new terminology in ICD-10-CM for late effects in ICD-9-CM and using the sequela seventh character replaces the late effects categories (905–909) in ICD-9-CM.

Fracture Coding

ICD-10-CM fracture codes provide greater specificity than ICD-9-CM. For example, ICD-10-CM fracture codes can indicate the fracture type (e.g., greenstick, transverse, oblique, spiral, comminuted, segmental), specific anatomical site, whether the fracture is displaced or not, laterality, routine versus delayed healing, nonunions, and malunions. Laterality and type of encounter (initial, subsequent, sequela) are significant components of the code expansion.

To provide additional specificity, the fracture seventh characters are expanded to include:

  • A, Initial encounter for closed fracture
  • B, Initial encounter for open fracture
  • D, Subsequent encounter for fracture with routine healing
  • G, Subsequent encounter for fracture with delayed healing
  • K, Subsequent encounter for fracture with nonunion
  • P, Subsequent encounter for fracture with malunion
  • S, Sequela

Some fracture categories provide seventh characters to designate the specific type of open fracture. These designations are based on the Gustilo open fracture classification and apply to categories S52 (Fracture of Forearm), S72 (Fracture of Femur), and S82 (Fracture of Lower Leg).

The Gustilo open fracture classification for extremities classifies open fractures into three major categories (types) depending on the mechanism of the injury, soft tissue damage, and degree of skeletal involvement. The classes are I, II, and III, with the third class further subdivided into A, B, or C.

The Gustilo classification is used to identify the severity of the soft tissue damage. Fracture healing, infection, and amputation rates correlate with the degree of soft tissue injury by Gustilo and helps determine the prognosis.

The seventh characters available for these open fractures are:

  • B, Initial encounter for open fracture type I or II
  • C, Initial encounter for open fracture type IIIA, IIIB, or IIIC
  • E, Subsequent encounter for open fracture type I or II with routine healing
  • F, Subsequent encounter for open fracture type IIIA, IIIB, or IIIC with routine healing
  • H, Subsequent encounter for open fracture type I or II with delayed healing
  • J, Subsequent encounter for open fracture type IIIA, IIIB, or IIIC with delayed healing
  • M, Subsequent encounter for open fracture type I or II with nonunion
  • N, Subsequent encounter for open fracture type IIIA, IIIB, or IIIC with nonunion
  • Q, Subsequent encounter for open fracture type I or II with malunion
  • R, Subsequent encounter for open fracture type IIIA, IIIB, or IIIC with malunion

In ICD-10-CM a fracture not indicated as displaced or nondisplaced should be coded to displaced, and a fracture not designated as open or closed should be coded to closed. While the classification defaults to displaced for fractures, it is very important that complete documentation is encouraged. The coding of the ICD-10-PCS procedure codes should match the diagnosis reported. When coding reductions of displaced fractures in ICD-10-PCS, the root operation of Replacement is assigned. However the treatment for nondisplaced fractures is coded to the procedure performed, such as casting (Immobilization) or inserting a pin (Insertion).

Aftercare Coding Example

A patient has a displaced, closed fracture of the greater trochanter of the right femur (S72.111). The following codes would be assigned for this case (all examples presume routine healing):

  • Patient seen in the ER, admitted, and surgery performed: S72.111A, Initial encounter for closed fracture
  • Admitted to long-term care for rehabilitation after hip replacement: S72.111D, Subsequent encounter for closed fracture with routine healing
  • Discharged from long-term care with home health to see for continued physical therapy: S72.111D, Subsequent encounter for closed fracture with routine healing
  • Patient visits hospital radiology department for X-ray: S72.111D, Subsequent encounter for closed fracture with routine healing
  • Patient to physician office for follow-up visit: S72.111D, Subsequent encounter for closed fracture with routine healing
  • Coding Aftercare

    The aftercare Z codes should not be used for aftercare for injuries or poisonings. The appropriate seventh characters are provided to identify this subsequent care. For aftercare of an injury, coders should assign the acute injury code with the appropriate seventh character "D" (or expanded choices for fractures) for subsequent encounter. This change will be significant for those post-acute settings that provide subsequent care for injuries.

    Currently V codes are used to report physical therapy and other aftercare of fractures and injuries such as removing casts and dressings.

    Poisoning, Adverse Effects, and Underdosing of Drugs

    Codes in categories T36–T65 are combination codes that include substances related to adverse effects, poisonings, toxic effects, and underdosing, as well as the external cause. No additional external cause code is required for poisonings, toxic effects, adverse effects, and underdosing codes.

    ICD-10-CM includes a table of drugs and chemicals; however, the columns have been restructured to group all poisoning columns together, followed by adverse effect and underdosing. Coding professionals must refer back to the tabular list rather than coding directly from the table of drugs and chemicals.

    Coding professionals may assign as many codes as necessary to describe all drugs and medicinal or biological substances. If two or more drugs and medicinal or biological substances are reported, code each individually unless the combination code is listed in the table of drugs and chemicals.

    Sequencing of codes from categories T36–T65 depends on the type of encounter. The guidelines indicate the correct sequencing, but these notes are also found at the Tabular to guide the correct coding and sequencing.

    Coders should assign the appropriate code for adverse effect (e.g., T36.0x5-) when the drug was correctly prescribed and properly administered. Use additional codes for all manifestations of adverse effects. Examples of manifestations are tachycardia, delirium, gastrointestinal hemorrhaging, vomiting, hypokalemia, hepatitis, kidney failure, or respiratory failure. The sequencing for coding an adverse effect is the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug (T36-T50). An example of the sequencing for an adverse effect is:

    Nausea due to Glipizide (taken correctly)

    R11.0 Nausea
    T38.3X5AAdverse effect of insulin and oral hypoglycemic [antidiabetic] drugs

    When coding a poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration), assign first the appropriate code from categories T36–T50. The sequencing for a toxic effect of substances chiefly nonmedicinal as to source (T51-T65) is the same as for coding poisonings. Poisoning codes have an associated intent: accidental, intentional self-harm, assault, and undetermined. Use additional code(s) for all manifestations of poisonings.

    When no intent of poisoning is indicated, code to accidental. Undetermined intent is only for use when there is specific documentation in the record that the intent of the poisoning cannot be determined. An example of the sequencing for a poisoning is:

    Coma due to acetaminophen overdose (suicide attempt)

    T39.1X2A Poisoning by 4-Aminophenol derivatives, intentional self-harm
    R40.20 Coma, unspecified

    Underdosing is a new concept in ICD-10-CM. It refers to taking less of a medication than is prescribed by a provider or a manufacturer's instruction. For underdosing, assign the code from categories T36–T50 (fifth or sixth character "6"). Codes for underdosing should never be assigned as principal or first-listed codes.

    If a patient has a relapse or exacerbation of the medical condition for which the drug is prescribed because of the reduction in dose, then the medical condition should be coded. Codes for noncompliance (Z91.12-, Z91.13-) or complication of care (Y63.61, Y63.8–Y63.9) should be used with an underdosing code to indicate intent, if known. An example of the sequencing for underdosing is:

    An exacerbation of congestive heart failure, the patient did not take his prescribed Lasix because of finances

    I50.9 Congestive heart failure NOS
    T50.1X6A Underdosing of loop [high-ceiling] diuretics
    Z91.120 Patient’s intentional underdosing of medication regimen due to financial hardship

    Coding Burns and Corrosions

    ICD-10-CM distinguishes between burns and corrosions. Burn codes apply to thermal burns (except sunburns) that come from a heat source, such as fire or hot appliance. They include electricity and radiation burns. Corrosions are burns due to chemicals. The guidelines are the same for burns and corrosions.

    Current burns (T20–T25) are classified by depth, extent, and agent (X code). Burns are classified by depth as first degree (erythema), second degree (blistering), and third degree (full-thickness involvement). Burns of the eye and internal organs (T26–T28) are classified by site, not by degree.

    For any documented infected burn site, coders should use an additional code for the infection. When coding burns, separate codes for each burn site should be assigned. Category T30, Burn and corrosion, body region unspecified, is extremely vague and should rarely be used.


    National Center for Health Statistics. "ICD-10-CM Official Guidelines for Coding and Reporting." 2015. 

    National Center for Health Statistics. "ICD-10-CM Index and Tabular." 2015. 

    Ann Zeisset ( is an independent consultant.

    Article citation:
    Zeisset, Ann M.. "Coding Injuries in ICD-10-CM (update)" (AHIMA, November 2014)