ADT^A18
Merge Patient Information
Patient Administration
Used to merge current and previous patient identification numbers: patient ID - internal, patient ID - external, alternate patient ID and patient account number. This is required, for example, when a patient has previously been registered under a new patient identification number because of an error or because there was insufficient time to determine the actual patient identification number. The merge event occurs when the decision is made to combine the information under either the new or old identifier(s). It is recommended that events A34, A35 and A36 be utilized in place of the A18 event whenever possible. [Event A18 is being kept for backwards compatibility.]
The PID segment contains the surviving patient ID information. The MRG segment contains the non-surviving information.
Message Types
Message Type
Trigger Structure
Return Structure
Event Flow
TriggerA18
SendADT_A18
ReceiveACK
Worked Examples
3.4.2 Merge patient information - trigger event A18 (basic example) -
HL7 v2
MSH|^~\&|REGADT|MCM|RSP1P8|MCM|198808181320|SECURITY|ADT^A18|MSG00002|P|2.2|
EVN|18|198808181318||
PID|||PATID5678^9^M11||JONES^WILLIAM^A^JR||19310615|M||C|303 EDWARDS
...DRIVE^GREENSBORO^NC^27410|GL|(919)294-1212|(919)288-0101||M||
...PATID12345001^2^M10|987654321|143257^NC|
MRG|PATID1234^5^M11||
NK1|JONES^NANCY^K|WIFE|
PV1|1|I|2000^2012^01||||004777^LEBAUER^SIDNEY^J.|||SUR||||||During the admission process, the admitting secretary used the medical record number of William A. Jones, III instead of William A. Jones, Jr. The billing number stayed the same since it is tied to the visit and numerous charges have already been incurred. The inclusion of the MRG segment with the old patient ID filled in, triggers the merge.