HL7 RTB_K13 Tabular Response

The rows-and-columns answer to a QBP_Q13 query.
HL7 message structure RTB_K13 groups and segments from HL7 v2.5.1 Hide structure

These are the generated groups and segments for the version selected at the top of the page. The article explains the workflow, and this panel follows the chosen HL7 version.

Message Structure

SegmentNameRequiredRepeatable
MSH
 Message Header Yes No
SFT
 Software Segment No Yes
MSA
 Message Acknowledgment Yes No
ERR
 Error No No
QAK
 Query Acknowledgment Yes No
QPD
 Query Parameter Definition Yes No
RTB_K13.ROW_DEFINITION
 Row Definition group No No
RDF
 Table Row Definition Yes No
RDT
 Table Row Data No Yes
DSC
 Continuation Pointer No No

RTB_K13 is the tabular response side of QBP_Q13. The receiver acknowledges the query, reports query status, echoes the query definition, and then returns a row definition plus zero or more row data segments.

In practice, RTB_K13 behaves like a small table delivered inside HL7 v2. That makes it convenient, but it also means column order, datatype, null handling, and continuation rules become part of the interface contract.

A small RTB K13 example

MSH|^~\&|RESULTS|CITYHOSP|PORTAL|CITYHOSP|20260717110002||RTB^K13^RTB_K13|RTB130001|P|2.5.1 MSA|AA|QBP130001 QAK|Q130001|OK|Q13^Recent result table^HL7nnn|2 QPD|Q13^Recent result table^HL7nnn|Q130001|123456^^^CITYHOSP^MR|20260701000000|20260717235959 RDF|4|PatientID^CX^20~Observation^CWE^80~Value^ST^40~ResultTime^DTM^24 RDT|123456^^^CITYHOSP^MR|718-7^Hemoglobin^LN|13.2 g/dL|20260715101900 RDT|123456^^^CITYHOSP^MR|4548-4^HbA1c^LN|6.8 %|20260716140700

What systems do with it

The requester reads MSA for message acknowledgment, QAK for query status, and QPD to confirm which query was answered. Then it uses RDF to understand the columns and RDT to read the row values.

If the response is large, DSC can carry continuation. The requester should either request the next increment or send a QCN_J01 cancellation if it does not want more rows.

How to read the structure

The top of the message looks ACK-like: MSH, MSA, optional ERR, QAK, and QPD. The optional row definition group contains required RDF and repeating RDT rows. If there are no hits, the receiver may return no row group and report the status in QAK.

RDF is not just documentation. It is the map for the RDT values. If your integration uses positional mapping, treat RDF as required even when a local profile says the requester already knows the columns.

Implementation traps

Do not ignore QAK because MSA says AA. A receiver can accept the query message and still report no rows, too many matches, or an application-level problem.

Also resist the temptation to overload one column with formatted text. If the response is supposed to be tabular, keep each column stable and typed enough that downstream systems can trust it.

Reference notes

The HL7 v2+ refactored RTB_K13 page shows the response with MSA, ERR, QAK, QPD, an optional row definition group containing RDF and RDT, and optional DSC. HL7 Chapter 5 describes RDF as the table row definition and RDT as row data.