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How to use Chapter 19 (Injuries, Poisonings, etc) in ICD-10-CM

This article provides in-depth information about ICD-10-CM Chapter 19 - Injury, Poisoning, and Certain Other Consequences of External Cause (S00-T88).

Also See: How ICD-10-CM Chapter 20 Works

In general, the ICD-10-CM code set provides greater specificity than ICD-9-CM, and this is true for the coding of injuries as well. The fundamental guidelines for coding injuries in ICD-10 remain the same as ICD-9, but ICD-10 does include some new features including seventh character extensions.

Chapter 19 contains 57% of the total volume of codes available, making it the largest chapter. The two alpha characters that are covered in this chapter are the S section code block related to various types of injuries isolated to a single body region, and the T section code block for injuries to unspecified body parts as well as poisonings and certain other consequences of external causes.

It is suggested that secondary code(s) from Chapter 20, External Causes of Morbidity, be used to indicate the cause of injury. Codes within the T section of Chapter 19 that already specify an external cause do not require an additional external code from Chapter 20 to specify the cause. Additional codes are to be used to identify retained foreign bodies if applicable (Z18). Birth traumas (P10-P15) and obstetric traumas (O70-O71) are excluded.

In ICD-10, injuries are categorized by the affected body part rather than the type of injury. All injuries to a region of the body (for example, the foot) are grouped together as opposed to grouping fractures together irrespective of the affected body part. Categories in ICD-9 included fractures (800-829), dislocations (830-839), and sprains and strains (840-848). Categories in ICD-10 are site specific, such as injuries to the ankle, foot and toes (S90-S99), injuries to the wrist, hand and fingers (S60-S69), and injuries to the neck (S10-S19). Chapter 19 uses the S section to code different types of injuries to a single body region and the T section to code injuries to unspecified body regions, poisonings, and certain other consequences of external causes.

Most categories in Chapter 19 require a seventh character extension for each applicable code. Additionally, except for fractures, most categories have three extensions or seventh character values to specify initial encounter (A), subsequent encounter (D), and sequela (S). Traumatic fracture categories have additional seventh character values.

When the patient is actively receiving treatment for an injury, the initial encounter (A) extension is used. This includes surgical treatment, emergency department encounters, and initial assessment and treatment by a new physician. When a patient has already received treatment for an injury before and is receiving routine care during the healing or recovery phase, then the subsequent encounter (D) extension is applicable. Examples include removal of fixation devices, change of cast, followup care, or medication adjustments following active treatment for an injury. When complications or other sequelae arise as a direct consequence of an injury, the sequela extension (S) is applicable. These would include scars or joint contractures forming following an injury. When using the seventh character S, both the injury code that precipitated the sequela and the code for the sequela itself is to be used. The S extension identifies the injury that precipitated the sequela, and the S is added to the injury code, not the sequela code. The type of sequela (for example, scar) is sequenced first, followed by the injury code. The late effects categories (905-909) of ICD-9 have been replaced by sequela in ICD-10. Aftercare Z codes are not to be used for followup care of injuries or poisonings as the seventh characters are provided to identify subsequent care with the D extension.

Coding of Fractures

Following the general trend, ICD-10 fracture codes provide greater specificity with regard to:

• type of fracture (for example, comminuted, spiral, segmental, oblique, transverse, greenstick)
• anatomical site (for example, ankle, foot, hand, wrist)
• displaced versus nondisplaced
• routine versus delayed healing
• malunion
• nonunion
• laterality
• type of encounter - initial (A), subsequent (D), or sequela (S)

Fractures code extensions are further expanded as follows to provide greater specificity:

• 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

Based on the mechanism of injury, damage to soft tissue, and degree of skeletal involvement, the Gustilo classification categorizes open fractures of extremities into three main classes I, II, and III, with class III further subdivided into A, B, or C.

• Class I, Low energy wound less than 1 cm
• Class II, Wound greater than 1cm with moderate soft tissue damage
• Class III, High energy wound greater than 1 cm with extensive soft tissue damage
• Class IIIA, Adequate soft tissue cover
• Class IIIB, Inadequate soft tissue cover
• Class IIIC, Associated with arterial injury

The ICD-10 code set provides seventh character extensions to designate the specific type of open fracture based on the Gustilo open fracture classification. This is applicable to fractures of the forearm (S52), fractures of the femur (S72), and fractures of the lower leg (S82). Prognosis is determined by the Gustilo classification as it identifies the severity of the injury based on soft tissue damage and is correlated to healing as well as infection and amputation rates. If a fracture is unspecified in terms of displaced or nondisplaced, ICD-10 guidelines require default coding as displaced, and if open or closed fracture type is not specified, guidelines require default coding as closed. Seventh character extensions based on the Gustilo open fracture classification are as follows:

• B, Initial encounter for open fracture type I or II (open NOS or not otherwise specified)
• 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

Coding Guidelines:

• Fractures are coded individually by site according to provisions in categories of code block S and the details furnished in the medical record
• Multiple fractures are sequenced by severity
• Traumatic fractures are coded with the appropriate seventh character for initial encounter (A, B, or C) while the patient is receiving active treatment
• The appropriate seventh character should be assigned for patients seeking delayed treatment or nonunion
• Complications arising from surgical treatment of fractures during the healing or recovery phase should be coded with appropriate complication codes
• Complications such as malunion or nonunion should be coded with appropriate seventh characters designated for subsequent care of nonunion (K, M, N) or subsequent care of malunion (P, Q, R)
• If a patient has osteoporosis that results in a fracture from a minor fall which would not normally break a healthy bone, a code from category M80 (not a traumatic fracture code) should be used

Coding Examples:

1. A patient with a previous trimalleolar fracture of the left ankle is seen for increased pain and is found to have malunion upon evaluation. The diagnosis code in this case would be S82.852P - displaced trimalleolar fracture of the left lower leg, subsequent encounter for closed fracture with malunion.
2. A patient visits the radiology department for an x-ray following a displaced closed fracture of the greater trochanter of the right femur. The diagnosis code in this case would be S72.111D - subsequent encounter for closed fracture with routine healing.

Coding of Injuries

Separate codes are assigned for each injury, and codes like T07, unspecified multiple injuries, should only be assigned if more specific information is not available. Traumatic injury codes (S00-T14.9) should not be used for normal healing of surgical wounds or for complications resulting from surgical wounds. The code for the most serious injury which is the focus of treatment, as outlined by the provider, is to be sequenced first. Superficial injuries like abrasions or contusions when occurring in association with severe injuries at the same site are not to be coded. The primary injury is sequenced first, with additional codes for injuries to nerves and spinal cord (for example, category S04) and/or injury to blood vessels (for example, category S15). Only if the primary injury is to nerves or blood vessels should this injury be sequenced first.

Coding Example: A patient had a 2-cm laceration of the left heel with a foreign body and has a scar present. The diagnosis code in this case would be S91.322S - laceration with foreign body, left foot, sequela.

Coding of Burns and Corrosions

There is a distinction between burns and corrosions in ICD-10-CM. Thermal burns from heat sources like fires or hot appliances and burns resulting from electricity and radiation are included in the burn codes, but sunburn is excluded. Separate codes are to be assigned for each burn site. Current burns (T20-T25) are classified based on depth, extent, and agent (X code). Burns of the eye and internal organs (T26-T28) are classified based on site, not degree. Burns resulting from chemicals are categorized as corrosions.

When more than one burn is present or when the reason for the admission/encounter is the treatment of multiple external burns, the highest degree of burn is sequenced first. When there are both internal and external burns present, or when the patient is admitted for burn injuries and associated related conditions like smoke inhalation or respiratory failure, the circumstances of admission may govern the selection of the first-listed diagnosis. Burns are classified according to the local site by the three-character category level (T20-T28), with subcategories identifying the highest degree of burn recorded in the diagnosis. Necrosis of burned skin is coded as a non-healed burn. Non-healing burns are coded as acute burns. Infected burns require an additional code for the infection. Vague codes like category T30 (burn and corrosion, body region unspecified) should be avoided. If the site of burn or corrosion is unspecified, codes can be assigned from category T31 (burns) or T32 (corrosions). These categories use the "rule of nines" in estimating the body surface area involved. Seventh character S for sequela are used for encounters to treat the late effects of burns or corrosions (for example, scars or joint contractures). If healing wounds coexist with the sequelae of healed burns or corrosions, both a code for the current burn with seventh character A or D and a code for sequela with seventh character S can be assigned to the same medical record. External cause codes identify the source of the burn, the intent, and the place where it occurred.

Coding Example: The patient is seen for initial assessment of the right ankle for burn injury resulting from contact with a space heater, and on evaluation is found to have a first-degree burn. In this case the appropriate diagnosis code will be T25.111A - burn of first degree of right ankle, initial encounter.

Coding of Poisoning, Underdosing, Adverse Effects and Toxic Effects

Combination codes in categories T36-T65 specify the substance that was taken and the intent as well as the external cause. No additional external cause code is required for poisonings, toxic effects, adverse effects, and underdosing codes. Several codes from the Tabular List may be used together to completely describe the poison. If the same causative agent has resulted in more than one adverse reaction, the code is to be assigned only once. If more than one biological substance is reported, each must be coded individually. Adverse effects can include such things as tachycardia, delirium, vomiting, hypokalemia, renal failure, or hepatitis.

For a properly prescribed and administered drug, the appropriate code for the nature of the adverse effect should be followed by the appropriate code for the adverse effect of the drug with a fifth or sixth character. For poisoning or reaction to improper use of medication (overdose or erroneous ingestion or incorrect route of administration), the appropriate code from categories T36-T50 should first be assigned, with an associated fifth or sixth character to assign intent (accidental, intentional self-harm, assault, or undetermined). Additional codes are to be used for manifestations of the poisoning and for abuse or dependence on a substance. Therefore, errors made in drug prescriptions and overdose of drug taken intentionally would both be coded as poisoning. In addition, manifestations of interactions between non-prescribed drugs taken in combination with prescribed drugs are also coded as poisoning, as are interactions of alcohol and prescribed drugs.

When less medication is taken than prescribed by the provider or manufacturer of the drug, it is termed as underdosing. Codes are assigned from categories T36-T50, but are never assigned as principal or first-listed status. If a medical condition has relapsed due to underdosing, that condition itself should be coded. Noncompliance codes (Z91.12- and Z91.13-) and complication of care (Y63.6-Y63.9) codes are used to indicate intent of underdosing if known. Toxic effects are coded from categories T51-T65 when a harmful substance is ingested or comes in contact with a person. These codes have an associated code specifying intent (intentional self-harm, accidental, assault, or undetermined).

Coding Example: A patient is experiencing nausea, vomiting, and fatigue after appropriately taking digoxin as prescribed and is evaluated for adjustment of medication. The appropriate diagnosis codes in this case would be R11.2 - nausea with vomiting, R53.83 - fatigue, and T46.0x5A- Table of Drugs and Chemicals, Digoxin, adverse effect. The code for the nature of the adverse effect is assigned first, followed by the code for the adverse effect of the drug.

Coding of Adult and Child Abuse, Neglect and Other Maltreatment

Categories include T74.- (adult and child abuse, neglect and other maltreatment, confirmed) and T76.- (adult and child abuse, neglect and other maltreatment, suspected). If abuse is confirmed, external codes from the assault section (X92-Y08) are used to identify the cause of any physical injuries, and a perpetrator code (Y07) is used to identify a known perpetrator. If abuse is ruled out, then encounter code Z04.71 (encounter for examination and observation following alleged adult physical abuse, ruled out) or the corresponding Z04.72 (encounter for examination and observation following alleged child physical abuse, ruled out) should be used instead of codes from T76. The same stands true for encounter codes Z04.41 and Z04.42 (encounters for examination and observation following alleged rape or sexual abuse, ruled out).

Coding Example: During an initial visit, a married woman admits to physical abuse by her husband, but this is not confirmed with any physical injuries. The appropriate diagnosis code in this case would be T76.11XA - adult physical abuse, suspected, initial encounter.

Coding of Complications of Care

Specific codes for pain associated with medical devices, implants, or grafts left in a surgical site are available in the T code section of the ICD-10-CM. Additional codes from category G89 can be used to specify acute or chronic pain from the presence of a device, implant, or graft. Complications and rejection of transplanted organs can be coded under category T86 if the complication affects the functioning of the transplanted organ. Two codes are used in combination to describe the complication, one from category T86 and a secondary code to identify the complication. Pre-existing conditions or conditions that developed following the transplant are excluded unless they affect the functioning of the transplanted organ. For example, code T86.1- is assigned for documented complications from a kidney transplant, but it should not be assigned to patients with chronic kidney disease unless transplant failure or rejection is documented. External causes are included in the complication of care codes along with the nature of the complication and the type of procedure that caused the complication; therefore, no external cause coding is necessary to indicate the type of procedure. Codes specific to the organ or body structures are available in the body system chapters for intraoperative and postoperative complications, and these codes should be sequenced first, followed by applicable specific complication codes.

Coding Example: A patient is seen with pain, redness, and swelling following a vascular graft in her forearm. The appropriate diagnosis code here is T82.7XXA - infection and inflammatory reaction due to other cardiac and vascular devices, implants and grafts, initial encounter.