DxCodebookFY2027 · Oct 1, 2026 – Sep 30, 2027

Category · FY2027

W94 Exposure to high and low air pressure and changes in air pressure

  • Header · not billable
  • Codes take a 7th character

W94 is not billable. The category heads 30 billable codes in FY2027, grouped under 4 subdivisions. Its codes take a 7th character, so none is complete with fewer than 7 characters.

Where it sits

  1. Chapter 20 External causes of morbidity (V00-Y99)
  2. W85-W99 Exposure to electric current, radiation and extreme ambient air temperature and pressure (W85-W99)
  3. W94 Exposure to high and low air pressure and changes in air pressure
Billable codes
30
Subdivisions
4
CC / MCC codes
0 / 0
HCC V28 codes
0
New FY2027
0
Index entries
0

Codes in W94

  1. W94.0
    Exposure to prolonged high air pressure +7th: A D S
    Needs 7th characterExempt
  2. W94.1
    Exposure to prolonged low air pressure
    Header
  3. W94.11
    Exposure to residence or prolonged visit at high altitude +7th: A D S
    Needs 7th characterExempt
  4. W94.12
    Exposure to other prolonged low air pressure +7th: A D S
    Needs 7th characterExempt
  5. W94.2
    Exposure to rapid changes in air pressure during ascent
    Header
  6. W94.21
    Exposure to reduction in atmospheric pressure while surfacing from deep-water diving +7th: A D S
    Needs 7th characterExempt
  7. W94.22
    Exposure to reduction in atmospheric pressure while surfacing from underground +7th: A D S
    Needs 7th characterExempt
  8. W94.23
    Exposure to sudden change in air pressure in aircraft during ascent +7th: A D S
    Needs 7th characterExempt
  9. W94.29
    Exposure to other rapid changes in air pressure during ascent +7th: A D S
    Needs 7th characterExempt
  10. W94.3
    Exposure to rapid changes in air pressure during descent
    Header
  11. W94.31
    Exposure to sudden change in air pressure in aircraft during descent +7th: A D S
    Needs 7th characterExempt
  12. W94.32
    Exposure to high air pressure from rapid descent in water +7th: A D S
    Needs 7th characterExempt
  13. W94.39
    Exposure to other rapid changes in air pressure during descent +7th: A D S
    Needs 7th characterExempt

Sources of each column. Rows marked +7th need a 7th character: pick one to build the full code; its code card has its own flags.

Instructions

Notes that also apply

Block W85-W99 instructions (Excludes1 8): printed on the block page.

Chapter 20 instructions (Notes 1): printed on the chapter 20 page.

7th characters

7th characters for W94 defined here

The appropriate 7th character is to be added to each code from category W94

7th characters for W94
7thMeaning (NCHS)
Ainitial encounter
Dsubsequent encounter
Ssequela

A code that takes a 7th character is invalid without it; the placeholder X fills a code shorter than 6 characters (Official Guidelines I.A.5). How 7th characters work.

Hierarchy