Review
Laterality relationship
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What we found
Same condition, opposite side.M26.641 and M26.642 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.
What to review
Report the side the documentation names. Where the code set provides a bilateral code and both sides are documented, use it instead of the pair.
Why it matters
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 / rule
ICD-10-CM tabular list (laterality variant derived from the code title)