ICD-10-CM 2027 diagnosis code
W55.21XABitten by cow, initial encounter
W55.21XA is a valid, billable ICD-10-CM code for bitten by cow, initial encounter. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About W55.21XA
W55.21XA is the ICD-10-CM diagnosis code for Bitten by cow, initial encounter. It belongs to category W55 (contact with other mammals), block W50-W64 (exposure to animate mechanical forces) and chapter 20 (external causes of morbidity). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
It is exempt from present-on-admission (POA) reporting, so no POA indicator is required.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as E906.3 (bite of other animal except arthropod).
7th character
Ainitial encounter
Other encounter types for W55.21:
Notes that apply from higher levels
Instructions written at a parent level also apply to W55.21XA.
Broader instructions also apply from W50-W64 Exposure to animate mechanical forces and Chapter 20: External causes of morbidity.
ICD-9-CM equivalent
Converter →- E906.3Bite of other animal except arthropodapproximate
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about W55.21XA
Is W55.21XA billable?
- Yes. W55.21XA is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
What does the "A" at the end of W55.21XA mean?
- It is the 7th character for initial encounter. Per the official guidelines, use it while the patient is receiving active treatment for the condition.
Can W55.21XA be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict W55.21XA as a principal diagnosis.
Is W55.21XA a CC or MCC?
- No. W55.21XA is neither a CC nor an MCC under MS-DRG v44.0.
What is the ICD-9 code for W55.21XA?
- The CMS General Equivalence Mappings map W55.21XA to ICD-9-CM E906.3.