2026 ICD-10-CM Diagnosis Code T70.20XAUnspecified effects of high altitude, initial encounter
T70.20XA is a billable ICD-10-CM diagnosis code for unspecified effects of high altitude, 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 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 922 through 923. Coders also document this condition as effects of high altitude. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Effect of other external causes, initial encounter.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Effects of high altitude
Coding GuidelinesGuidance
The appropriate 7th character is to be added to each code from block Effects of air pressure and water pressure (T70). 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
Barotrauma
Barotrauma means injury to your body because of changes in barometric (air) or water pressure. One common type happens to your ear. A change in altitude may cause your ears to hurt. This can happen if you are flying in an airplane, driving in the mountains, or scuba diving.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T70.20XA to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T70.20XAOverview
Is T70.20XA (Unspecified effects of high altitude) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified effects of high altitude, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T70.20XA mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for unspecified effects of high altitude, such as an emergency visit or first evaluation.
What MS-DRG does T70.20XA group to?
When unspecified effects of high altitude, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 922, 923, with relative weights from 1.0177 to 1.7494 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T70.20XA?
Under the General Equivalence Mappings, unspecified effects of high altitude, initial encounter converts to ICD-9-CM 993.2 (eff high altitud NEC/NOS). 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.
