G56.40 (Causalgia of unspecified upper limb) compared with G56.42 (Causalgia of left upper limb), from the official CMS tabular data. G56.40 and G56.42 code the same condition on opposite sides.
Same condition; these differ only in which side is documented.
These codes share a category and title and differ only in the side affected. The documentation decides which applies, and a bilateral code is reported only where the code set provides one.
Source: ICD-10-CM tabular list (laterality variant derived from the code title)
Same condition, opposite side. G56.40 and G56.42 name the same condition on opposite sides of the body.
Same category and title, differing only in which side is affected — the documentation decides which one applies, and a bilateral code is reported only where the code set provides one.
| G56.40Causalgia of unspecified upper limb | G56.42Causalgia of left upper limb | |
|---|---|---|
| Billing status | Billable | Billable |
| Classification | G00-G99 — Diseases of the Nervous System (G00-G99) | G00-G99 — Diseases of the Nervous System (G00-G99) |
| Definition | Causalgia of unspecified upper limb is a billable ICD-10-CM diagnosis code (G56.40). | Causalgia of left upper limb is a billable ICD-10-CM diagnosis code (G56.42). |
Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources