Which HL7 data type is used for transmitting a patient identifier and its scope?

The correct choice for transmitting a patient identifier and its scope is the CX data type. The CX (Extended Composite ID with Check Digit) data type is specifically designed to represent identifiers that need to be unique and may include additional components such as check digits, assigning authority, and scope.

This makes the CX type particularly useful in healthcare settings where patient identifiers must not only denote a unique individual but also include context about the issuer of that identifier (for example, ensuring it can be linked back to a particular organization or system). The structure of CX ensures that all relevant information surrounding the identifier is included, which is critical for clarity and data integrity in health information exchange.

In contrast, the other options do not adequately fulfill the requirement for a comprehensive patient identifier and its context. The CK type, for instance, is more focused on check digit elements but does not encompass additional necessary data. CN (Composite Name) type represents a person's name rather than an identifier, and the XCN (Extended Composite Name and Number) contains name and id information but is not strictly designated for identifiers, making it insufficient for this particular use case.