ICD-10 Reminder Series: Section 19. Injury, Poisoning, and Certain Other Consequences of External Causes: Part 2

ICD-10 Reminder Series: Section 19. Injury, Poisoning, and Certain Other Consequences of External Causes: Part 2

Posted by Vikas Chawla
Dec 23, 2019 1:12:16 PM

Let’s pick up where we left off in the previous Blog posting for Chapter 19. In this blog we will review coding of Burns, Corrosions, Adverse effect, Poisoning and Toxic effects.

A recent study showed that poisonings are the leading cause of unintentional injury deaths, surpassing motor vehicle accidents. Each year, over 1.1 million people report burn injuries. And in 2015 there were 215 fatal workplace injuries due to exposure to harmful substances. So it’s no wonder the World Health Organization expanded the code categories and selections for injuries in ICD 10-CM.

Burns and Corrosions

Chapter 19 ICD-10-CM guidelines make a distinction between Burns and Corrosions. Burns are classifieds under thermal burns which are burns from heat sources such as fire, electricity, friction, hot air or gasses, hot objects, or radiation. On the other hand, corrosions are caused by chemical burns such as acids, lime, alkaline, or caustics.

While assigning burn codes, the depth of the burn it needs to be considered.

There are 3 categories:

  1. First-Degree Burns or erythema
  2. Second-Degree Burns or Blistering
  3. Third-Degree Burns or Full Thickness

If multiple burns are present, the burn with the highest degree should be sequenced first over other burns.

An additional code, for the extent of body surface involved, needs to be reported. Category T31 is for burns classified according to extent of body surface involved and Category T32 is for Corrosions classified according to extent of body surface involved. There is an instructional note stating codes from Category T31 and T32 should be used as the primary diagnosis only when the site of the burn or corrosion is unspecified. When the site of the burn or corrosion is known, a code from T31 or T32 should be used as a supplementary code to T20-T25.

Let’s go through an example to understand the guidelines:

Example: A patient presents to the emergency department after being burned in a house fire. The emergency department physician’s documentation indicates the patient has first-, second-, and third-degree burns on his upper back, first- and second-degree burns on his left palm, and second- and third-degree burns on his left upper arm. A patient has burns on 75 percent of his body surface.

Approximately 1/3 (33 percent) of his body surface are third-degree burns.

ICD-10-CM codes for this scenario are:

T21.33XA Burn of third degree of upper back, initial encounter

T22.332A Burn of third degree of left upper arm, initial encounter

T23.252A Burn of second degree of left palm, initial encounter

T31.73 Burns involving 70-79% of body surface with 30-39% third-degree burns

Adverse Effects:

Adverse effects are side effects of a drug which is correctly prescribed and properly administered. While coding an adverse effect of a drug, the coder should assign the most appropriate code that supports the nature of the adverse effect (the toxicity code), followed by a second code for the adverse effect (the symptom or condition) as a result of the drug.

Here is an example: A seven-year-old boy presents to pediatric office with vomiting due to Benadryl. Mother administered the proper dosage.

  • T45.0x5A Adverse effect of antiallergic and antiemetic drugs, initial encounter
  • R11.10 vomiting


Improper use of a medication is considered a poisoning such as overdosing, wrong route of administration, or wrong substance given. While coding for poisoning the coder should first assign the most appropriate code from categories T36-T50. These codes include a 5th or 6th character which describes the intent of the poisoning, such as accidental, intentional, assault, or unknown. If the documentation does not clearly specify the intent, or the intent is unknown, a code including the term ‘undetermined’ should be selected. Coders should also remember to apply the 7th character to describe the encounter:

A = Initial encounter

D = Subsequent encounter

S = Sequela

If the documentation indicates there is abuse or dependence of a substance, then an additional code for this diagnosis should be assigned.

Example: A patient was found unconscious by a family member. It was determined that the patient took an overdose of Methadone and is in Coma. Patient has history of taking Methadone for the past 3 years.

  • T40.3X4A Poisoning by methadone, undetermined
  • R40.20 Unspecified coma
  • F11.20 Opioid dependence


Underdosing includes both taking less of the medication than what was prescribed and stopping the medication without direction of the physician. While coding of underdosing the coder should assign the most appropriate code from categories T36-T50. Codes for the underdosing should never be sequenced as the primary condition. Instead, the patient’s condition for taking the medication or the patient’s exacerbation of the medical condition should be coded first.

Additional codes for non-compliance (Z91.12_, Z91.13_ and Z91.14_) or complication (Y63.6 – Y63.9) should be reported if the intent of the underdosing is known.

Example: A 14-year old girl with known seizure disorder presents with having a seizure at school. Mother reported the teenager had forgotten to take her Dilantin for the past several days.

  • G40.909 Epilepsy, unspecified, not intractable, without status epilepticus
  • T42.0X6 Underdosing of hydantoin derivatives, initial encounter
  • Z91.130 Patients unintentional underdosing of medication regimen for other reason

Toxic Effects:

A Toxic Effect occurs when a harmful substance is ingested or comes in contact with a person. These substances include chemicals, organic solvents like petroleum, corrosive substances, household items like soap and cleaners, metals such as lead and mercury, and gases, fumes, vapors, venom, and even animal or plants like seafood and mushrooms. These toxic effect codes are found in categories T51-T65. Example: Paramedics arrived at a trail head of a local mountain trail, after a 911 call from a hiker who had been bitten by a rattlesnake on the left ankle. The patient had left foot numbness and was nauseous.

  • T63.011A Toxic effects of rattlesnake venom, accidental (unintentional)
  • R20.2 Paresthesia of skin
  • R11.0 Nausea without vomiting

With the greater level of specificity in coding injuries in ICD 10-CM, it is important for coders and auditors to not only understand these guidelines but to also know the clinical documentation requirements related to injuries. Training providers on these requirements will ensure patient encounter is meaningful, accurate, and will allow you to code the highest level of specificity. Look out next week for our posting on Chapter 20: External Causes of Morbidity. In the meantime, be sure to apply safeguards in your homes and workplaces to avoid becoming a national injury statistic.

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