HL7 PID Segment

The HL7 PID segment is found in every type of ADT message (i.e. ADT-A01, ADT-A08, etc.) and contains 30 different fields with values ranging from patient ID number, to patient sex, to address, to marital status, to citizenship. The PID segment provides important identification information about the patient and, in fact, is used as the primary means of communicating the identifying and demographic information about a patient between systems. Due to the nature of the information found in the PID segment, it is unlikely to change frequently.

The fields in the PID segment are as follows:

1 4 SI O   Set ID – Patient ID
2 20 CX O   Patient ID (External ID)
3 20 CX R Y Patient ID (Internal ID)
4 20 CX O Y Alternate Patient ID – PID
5 48 XPN R Y Patient Name
6 48 XPN O   Mother’s Maiden Name
7 26 TS O   Date/Time of Birth
8 1 IS O   Sex
9 48 XPN O Y Patient Alias
10 1 IS O   Race
11 106 XAD O Y Patient Address
12 4 IS B   Country Code
13 40 XTN O Y Phone Number – Home
14 40 XTN O Y Phone Number – Business
15 60 CE O   Primary Language
16 1 IS O   Marital Status
17 3 IS O   Religion
18 20 CX O   Patient Account Number
19 16 ST O   SSN Number – Patient
20 25 DLN O   Driver’s License Number – Patient
21 20 CX O Y Mother’s Identifier
22 3 IS O   Ethnic Group
23 60 ST O   Birth Place
24 2 ID O   Multiple Birth Indicator
25 2 NM O   Birth Order
26 4 IS O Y Citizenship
27 60 CE O   Veterans Military Status
28 80 CE O   Nationality
29 26 TS O   Patient Death Date and Time
30 1 ID O   Patient Death Indicator

*Note: For the complete HL7 Standard, please go to the HL7 organization website.

The HL7 standard allows for several different types of patient identification numbers in the first four fields of the PID segment. The differences are described below:

  • PID-1: Set ID – Patient ID – a number to identify the transaction
  • PID-2: Patient ID (External ID) – the patient identifier number used by one or more outside institutions (i.e. a physician’s office that is referring the patient)
  • PID-3: Patient ID (Internal ID) – the primary, unique patient identifier number used by the facility
  • PID-4: Alternate Patient ID – an alternate, additional, temporary or pending patient identification number

In HL7 pipe and hat format, the PID segment (shown in red) for an ADT-A01 message would look like this:



PID|||PATID1234^5^M11||JONES^WILLIAM^A^III||19610615|M-||C|1200 N ELM





AL1|1||^Penicillin||Produces hives

AL1|2||^Cat dander|Respiratory distress


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