2026 ICD-10-CM Diagnosis Code S20.461SInsect bite (nonvenomous) of right back wall of thorax, sequela
S20.461S is a billable ICD-10-CM diagnosis code for insect bite (nonvenomous) of right back wall of thorax, sequela. The 7th character S marks it as a sequela code, which reports a problem that remains after the original condition has resolved. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 604 through 605. The code is exempt from POA reporting. Coders also document this condition as bite wound of posterior chest wall. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Injury, sequela.
Code Identity
Code Classification
Present on Admission (POA)Billing
S20.461S is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Bite wound of posterior chest wall
- Nonvenomous insect bite of back with infection
- Nonvenomous insect bite of posterior thorax with infection
- Nonvenomous insect bite of right half of posterior chest wall
- Nonvenomous insect bite of right half of posterior thorax with infection
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Superficial injury of thorax (S20). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Insect Bites and Stings
Most insect bites are harmless, though they sometimes cause discomfort. Bee, wasp, and hornet stings and fire ant bites usually hurt. Mosquito and flea bites usually itch. Insects can also spread diseases. In the United States, some mosquitoes spread West Nile virus.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert S20.461S to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S20.461SOverview
Is S20.461S (Insect bite (nonvenomous) of right back wall of thorax) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report insect bite (nonvenomous) of right back wall of thorax, sequela on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character S in S20.461S mean?
The final character S makes this a sequela code: it reports a lingering problem that remains after the insect bite (nonvenomous) of right back wall of thorax itself has resolved, not the original event.
What MS-DRG does S20.461S group to?
When insect bite (nonvenomous) of right back wall of thorax, sequela is the principal diagnosis on an inpatient stay, it groups to MS-DRG 604, 605, with relative weights from 0.9160 to 1.4721 depending on complications. Higher weights mean higher Medicare reimbursement.
Is S20.461S exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for insect bite (nonvenomous) of right back wall of thorax, sequela on inpatient claims.
What is the ICD-9 equivalent of S20.461S?
Under the General Equivalence Mappings, insect bite (nonvenomous) of right back wall of thorax, sequela converts to ICD-9-CM 906.2 (late eff superficial inj). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
