Physiological Systems (5A) ICD-10-PCS
The 5A body system covers Extracorporeal or Systemic Assistance and Performance procedures on physiological systems, with 120 ICD-10-PCS codes across 3 root operations, 114 of them billable in fiscal year 2026. Each root operation defines a distinct procedural objective, and the info icons show the official definition with a preview of the codes inside.
Root Operations in This Body System 3 operations · 120 codes
| Chars 1–3 | Root Operation | Codes | Billable |
|---|---|---|---|
| 5A0 | AssistanceTaking over a portion of a physiological function by extracorporeal means | 74 | 72 |
| 5A1 | PerformanceCompletely taking over a physiological function by extracorporeal means | 42 | 40 |
| 5A2 | RestorationReturning, or attempting to return, a physiological function to its original state by extracorporeal means | 4 | 2 |
The info icon shows the official root operation definition and previews the codes in that range.
About the 5A Body System
The ICD-10-PCS root operation category Physiological Systems (section 5A) pertains to procedures that use extracorporeal methods to support or manage body functions. These operations involve assisting, performing, or restoring physiological functions outside the body.
Within this classification of Extracorporeal or Systemic Assistance and Performance, three specific types of procedures are defined. Assistance (5A0) involves taking over part of a physiological function to support the body temporarily. Performance (5A1) means completely substituting the function by extracorporeal means, such as when a machine fully performs the role of an organ. Lastly, Restoration (5A2) refers to efforts that return or attempt to return a physiological function to its normal state using external support. These distinctions are crucial for accurately coding procedures involving heart-lung machines, dialysis, or other life-support technologies, reflecting the specific nature of assistance provided to the physiological systems.
Questions About This Page
How many codes are in the 5A body system?
The 5A body system contains 120 ICD-10-PCS codes in FY 2026, organized into 3 root operations. 114 of them are billable on inpatient claims.
What is a root operation?
The root operation is the third character of every ICD-10-PCS code and names the objective of the procedure. Drainage takes fluid out, Excision cuts out a portion of a body part, and Resection removes all of one. Picking the right root operation is the central skill of PCS coding, so each one above carries its official CMS definition.
Related References
Source: CMS FY 2026 ICD-10-PCS order file and code tables, effective October 1, 2025 through September 30, 2026.
