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ICD-10-CM 2027 diagnosis code

T70.3XXACaisson disease [decompression sickness], initial encounter

✓ Billable / specificRequires 7th characterCC — complication/comorbidity

T70.3XXA is a valid, billable ICD-10-CM code for caisson disease [decompression sickness], initial encounter. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About T70.3XXA

T70.3XXA is the ICD-10-CM diagnosis code for Caisson disease [decompression sickness], initial encounter. It belongs to category T70 (effects of air pressure and water pressure), block T66-T78 (other and unspecified effects of external causes) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 922 (Other Injury, Poisoning and Toxic Effect Diagnoses with MCC, relative weight 1.6238) and DRG 923 (Other Injury, Poisoning and Toxic Effect Diagnoses without MCC, relative weight 0.9973), in MDC 21 (Injuries, Poisonings and Toxic Effects of Drugs), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 993.3 (Caisson disease).

7th character

Ainitial encounter

CC/MCC status for this injury by encounter: CC for A; Neither CC nor MCC for D, S.

Other encounter types for T70.3:

Notes that apply from higher levels

Instructions written at a parent level also apply to T70.3XXA.

Broader instructions also apply from T66-T78 Other and unspecified effects of external causes and Chapter 19: Injury, poisoning and certain other consequences of external causes.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 993.3Caisson diseaseapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about T70.3XXA

Is T70.3XXA billable?

Yes. T70.3XXA is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

What does the "A" at the end of T70.3XXA mean?

It is the 7th character for initial encounter. Per the official guidelines, use it while the patient is receiving active treatment for the condition.

Can T70.3XXA be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict T70.3XXA as a principal diagnosis.

Is T70.3XXA a CC or MCC?

T70.3XXA is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does T70.3XXA group to?

T70.3XXA is used in the MS-DRG v44.0 logic for MS-DRG 922 (Other Injury, Poisoning and Toxic Effect Diagnoses with MCC) and MS-DRG 923 (Other Injury, Poisoning and Toxic Effect Diagnoses without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for T70.3XXA?

The CMS General Equivalence Mappings map T70.3XXA to ICD-9-CM 993.3.