Documentation does not clearly establish whether pneumonia was present on admission, and the provider has not stated that it is clinically impossible to determine. Which POA concept distinction should the coder recognize?

CMS POA instructions distinguish indicator U (documentation is insufficient to determine POA status) from W (the provider documents that it is clinically undetermined whether the condition was present on admission). They are not interchangeable with each other or with Y/N. Querying for clarification may be appropriate when documentation is unclear, but the conceptual difference between U and W remains required knowledge.