Alphabetic Index FY2027

W94.31XD

Exposure to sudden change in air pressure in aircraft during descent, subsequent encounter

FY2027Chapter 20: External causes of morbidity/W85–W99 Exposure to electric current, radiation and extreme ambient air temperature and pressure

BillableComplete code, valid to report

W94.31XD (also written W9431XD) is a billable ICD-10-CM diagnosis code for exposure to sudden change in air pressure in aircraft during descent, subsequent encounter. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 30 codes in category W94 (Exposure to high and low air pressure and changes in air pressure). Its 7th character, D, means subsequent encounter. Its coding notes include 8 Excludes1 entries.

7th character

Category W94 requires a 7th character. W94.31 has only 5 characters, so a placeholder X fills the 6th position.

Assembled code W94.31XD Open code

Guidelines tip

From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.

An external cause code is never a principal or first-listed diagnosis. Its 7th character is assigned for each encounter and should match the injury or condition code.

Guidelines I.C.20.a.2; I.C.20.a.6External cause codesRead the official text

Excludes1

Not coded here. The listed conditions generally should not be reported together.

Also from chapter/block level (8 notes)
Inherited from W85–W99 Exposure to electric current, radiation and extreme ambient air temperature and pressure
  • exposure to:
    • failure in dosage of radiation or temperature during surgical and medical care (Y63.2-Y63.5)
    • lightning (T75.0-)
    • natural cold (X31)
    • natural heat (X30)
    • natural radiation NOS (X39)
    • radiological procedure and radiotherapy (Y84.2)
    • sunlight (X32)

Notes

Also from chapter/block level (1 note)
Inherited from Chapter 20 External causes of morbidity
  • This chapter permits the classification of environmental events and circumstances as the cause of injury, and other adverse effects. Where a code from this section is applicable, it is intended that it shall be used secondary to a code from another chapter of the Classification indicating the nature of the condition. Most often, the condition will be classifiable to Chapter 19, Injury, poisoning and certain other consequences of external causes (S00-T88). Other conditions that may be stated to be due to external causes are classified in Chapters I to XVIII. For these conditions, codes from Chapter 20 should be used to provide additional information as to the cause of the condition.