2027 ICD-10-CM Diagnosis Code S20.462AInsect bite (nonvenomous) of left back wall of thorax, initial encounter
S20.462A is a billable ICD-10-CM diagnosis code for insect bite (nonvenomous) of left back wall of thorax, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 606 through 607, 963 through 965. Coders also document this condition as nonvenomous insect bite of back with infection. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Superficial injury; contusion, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Nonvenomous insect bite of back with infection
- Nonvenomous insect bite of chest wall with infection
- Nonvenomous insect bite of left half of chest wall with infection
- Nonvenomous insect bite of left half of posterior chest wall
- Nonvenomous insect bite of left half of posterior thorax with infection
- Nonvenomous insect bite of posterior thorax with infection
- Wound of left half of chest wall due to nonvenomous insect bite
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 2027, published by CMS and the National Center for Health Statistics.
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to S20.462A: its own notes plus those printed at S20, block S20-S29, and Chapter 19. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- injuries of breast
- injuries of chest (wall)
- injuries of interscapular area
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- burns and corrosions (T20-T32)
- effects of foreign body in bronchus (T17.5)
- effects of foreign body in esophagus (T18.1)
- effects of foreign body in lung (T17.8)
- effects of foreign body in trachea (T17.4)
- frostbite (T33-T34)
- injuries of axilla
- injuries of clavicle
- injuries of scapular region
- injuries of shoulder
- insect bite or sting, venomous (T63.4)
Use Additional Code
Add a second code, after this one, to fully describe the condition.
- code to identify any retained foreign body, if applicable (Z18.-)
Notes
General instructions on how these codes are used.
- Use secondary code(s) from Chapter 20, External causes of morbidity, to indicate cause of injury. Codes within the T section that include the external cause do not require an additional external cause code
- The chapter uses the S-section for coding different types of injuries related to single body regions and the T-section to cover injuries to unspecified body regions as well as poisoning and certain other consequences of external causes.
7th Character
Every code in the category takes a 7th character from the listed values, with the placeholder X filling any empty positions before it.
- The appropriate 7th character is to be added to each code from category S20
- Ainitial encounter this code
- Dsubsequent encounter
- Ssequela
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
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 S20.462A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About S20.462AOverview
Is S20.462A (Insect bite (nonvenomous) of left back wall of thorax) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report insect bite (nonvenomous) of left back wall of thorax, initial encounter on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What does the 7th character A in S20.462A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for insect bite (nonvenomous) of left back wall of thorax, such as an emergency visit or first evaluation.
What MS-DRG does S20.462A group to?
When insect bite (nonvenomous) of left back wall of thorax, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 964, 965, 607, 963, 606, with relative weights from 0.8772 to 2.6361 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of S20.462A?
Under the General Equivalence Mappings, insect bite (nonvenomous) of left back wall of thorax, initial encounter converts to ICD-9-CM 911.4 (insect bite trunk). The mapping is approximate, so confirm the match fits the documentation.
