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Holy Cow! New (and Unusual) ICD-10 Codes

February 27, 2018 BY Alanna Moriarty

Holy Cow! New (and Unusual) ICD-10 Codes

*Updated August 2019

In October 2015, the United States officially adopted the ICD-10 medical coding system. Much like the ICD-9 system before it, ICD-10 codes are unique alphanumerical sequences based on the International Classification of Diseases released by the World Health Organization (WHO). Healthcare providers use these codes to accurately record patient diagnoses, which facilitates the collection and sharing of diagnostic data as well as national and international mortality and injury statistics.

Though the ICD-10 coding system was developed in 2003 and updated annually based on WHO reports, U.S. implementation was delayed for several years. ICD-10 contains about 70,000 unique diagnostic codes, a stark contrast to ICD-9’s 13,000 codes. The new diagnosis codes are longer in ICD-10 than in ICD-9, increasing from three-to-five digits to three-to-seven digits. This drastic increase in the number of codes is accredited to the improved specificity of ICD-10 codes.

In the ICD-9 system, only 20 codes were used as broad diagnosis indicators for any injury resulting from an animal encounter. The ICD-10 system uses nearly 250 codes to describe specific injuries by various animals as well as the stage of treatment. The expansion of diagnosis codes within the ICD-10 system has allowed for extremely specific and often amusing new codes and descriptions, like those listed in the following tables.

Top 10 Animal Related Diagnoses by ICD-10 Code

ICD-10 Code Description Total # Diagnoses ICD-9 Code

W5501XA

Bitten by cat, initial encounter

3,567

E9063

T63.301A

Toxic effect of unspecified spider venom, accidental, initial encounter

1,237

9895

T63.441A

Toxic effect of venom of bees, accidental, initial encounter

1,192

9895

W5503XA

Scratched by cat, initial encounter

525

E9068

T63.001A

Toxic effect of unspecified snake venom, accidental, initial encounter

495

9895

T63.011A

Toxic effect of rattlesnake venom, accidental, initial encounter

478

9895

W5501XD

Bitten by cat, subsequent encounter

408

E9063

T63.331A

Toxic effect of venom of brown recluse spider, accidental, initial encounter

316

9895

T63.461A

Toxic effect of venom of wasps, accidental, initial encounter

367

9895

W5512XA

Struck by horse, initial encounter

349

E9068

Fig 1 Data from Definitive Healthcare based on full-year 2018 reports of all-payer inpatient primary and secondary diagnoses. Full-year 2018 ICD-10 data is available in the Definitive Healthcare claims database. Partial-year 2019 data is also available.

There are 22 “chapters” in the ICD-10 coding system, each with a different letter denoting the diagnosis category. For example, chapter 19 is titled “Injury, poisoning, and certain other consequences of external causes.” The two letters used are S, for injuries, and T, for poisoning and other injuries caused by external encounters, and there are subcategories for each letter. Included under “T” are bites from venomous and poisonous animals and the effects of these toxins.

Chapter 20, “External causes of morbidity and mortality,” uses letters V through Y. The subcategory W50 is reserved for unintentional incidents where a patient is injured, accidentally or purposefully, by another person or animal. Though these incidents can certainly cause serious injury, the descriptions of these codes may come as a surprise to those reading them.

One code that stands out is W55.22XA, “struck by a cow.”  While it is more common for people to be struck by a vehicle, one can still hope both cow and patient were being safe and wearing seat belts. Another standout is code W50.3XXA, “accidental bite by another person, initial encounter.” This is not to be confused with code Y041XXA, “assault by human bite subsequent encounter.”

Top 10 Non-Venomous Animal Related Diagnoses by ICD-10 Code (Alphabetical)

ICD-10 Code Description Total # Diagnoses ICD-9 Code

W57.XXXA

Bitten or stung by nonvenomous insect and other nonvenomous arthropods, initial encounter

7,230

E9064

W54.0XXA

Bitten by dog, initial encounter

5,938

E9060

W55.01XA

Bitten by cat, initial encounter

3,567

E9063

W54.0XXD

Bitten by dog, subsequent encounter

1,023

E9060

W50.0XXA

Accidental hit or strike by another person, initial encounter

702

E9179

W55.03XA

Scratched by cat, initial encounter

525

E9068

W55.01XD

Bitten by cat, subsequent encounter

408

E9063

W51.XXXA

Bitten or stung by nonvenomous insect and other nonvenomous arthropods, subsequent encounter

470

E9179

W55.22XA

Struck by cow, initial encounter

181

E9068

W54.1XXA

Struck by dog, initial encounter

139

E9068

Fig 2 Data from Definitive Healthcare based on full-year 2018 reports of all-payer inpatient primary and secondary diagnoses. Does not include diagnoses involving venomous creatures. Full-year 2018 ICD-10 data is available in the Definitive Healthcare platform. Partial-year 2019 data (January to May 2019) is also available in the platform.

The shift from ICD-9 to ICD-10 codes will likely help healthcare providers and payers gain a better understanding of their patients and of overall population health. Because ICD-10 codes are so much more specific, providers can gather more detailed information faster, improving their ability to make informed treatment decisions. Additionally, because the codes themselves are specialized, physicians won’t have to spend as much time taking detailed notes to fill information gaps from generalized ICD-9 codes, improving diagnostic accuracy. This should increase overall efficiency and prevent errors in billing and reimbursement.

Other key differences between ICD-9 and ICD-10 codes involve detail about the patient’s condition. Where ICD-9 codes only stated the injury, ICD-10 codes give both injury and location. A venomous insect bite on the right lower leg will have a different ICD-10 code than the same injury on the lower left leg, and so on. Similarly, accidental injuries have different diagnosis codes than purposeful injuries, such as with codes T63.441A, “toxic effect of bee venom, accidental” and T63.442A, “toxic effect of bee venom, intentional self-harm.”

The new coding system also indicates whether the patient is being seen for the first time for an injury or whether there are ongoing complications stemming from an existing injury.

Top 20 Most Diagnosed Animal-Related ICD-10 Codes

Animal

ICD-10 Code Series

Total # Related Diagnoses

Related ICD-9 Code(s)

Ants

T63.42

116

9895

Arthropod, venomous

T63.48

631

9895

Bees

T63.44

1,489

9895, 9091, V5889

Cat

W55.0

4,707

E9063, E9068, E9295

Stingray

T63.51

23

9895

Cow

W55.2

201

E9068

Dog

W54

7,553

E9060, E9068, E9295

Fish, venomous

T63.591

18

9895

Hornets

T63.45

109

9895

Horse

W55.1

496

E9068

Human

W50, W51, W52

1,747

E9687

Insect or other Arthropod, nonvenomous

W57.XXX

374

E9064, E9295

Jellyfish

T63.621

15

9895

Mammal, other

W55.8

25

E9068

Rat

W53.1

50

E9061

Scorpion

T63.2X

113

9895

Snake, venomous

T63.0

1,441

9895

Spider, venomous

T63.3

665

9895

Undetermined venomous animal

T63.89

160

9895, V5889

Wasps

T63.46

474

9895

Fig 3 Not an exhaustive list of all animal- or insect-related ICD-10 codes. List only represents animal-related ICD-10 codes with quantifiable all-payer diagnoses in calendar year 2018. Does not include allergy diagnoses. 

One example of the insight gleaned from ICD-10 codes is that, despite popular debate, cats are less dangerous than dogs—but more dangerous than some venomous invertebrates. Almost 5,000 people saw a physician for a cat-related injury compared to about 7,500 people for a dog-related injury. More accurate coding can help providers be more proactive in anticipating the care they will have to provide.

For now, only entities covered by the Health Insurance Portability and Accountability Act (HIPAA) are required to switch from ICD-9 to ICD-10 codes. However, though not necessary, organizations that are involved with insurance coverage and worker’s compensation could leverage the new codes to easily coordinate coverage and benefits. The ICD-10 coding system has been in use by WHO since 1990, and by countries internationally since 1994, though the U.S. only adopted it in late 2015. Currently ICD-11 is in development, and was tested throughout 2017. It is estimated that this coding system will come into effect in January 2022.

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