The PEO (Product Experience Observation) segment carries the clinical narrative of an adverse event associated with a drug or medical device. It records what was observed, when it began and ended, how serious the event was, and who first noted it — the heart of every post-market surveillance report transmitted to a regulator.
Purpose
PEO conveys the observation that something went wrong with a marketed product. Where PES identifies the reporting party and PCR describes the product implicated, PEO answers what happened to the patient — the symptoms, the timeline, the severity, the outcome, and the qualifications of the observer making the report.
Used in
PEO appears in product-experience / post-market surveillance PEX messages reporting adverse drug or device events to regulators such as the FDA, EMA, or MHRA. A single PEX transaction may contain multiple PEO segments when more than one distinct observation is associated with a product complaint.
Field-by-field
Each row below reflects the HAPI HL7 v2.5.1 javadoc for PEO. Required fields are marked R; everything else is optional. Repeating fields are flagged Y. Data type names link to their reference page; lengths are not standardised at the segment level for v2.5.1 and are shown as "—".
| Seq | Name | Data Type | Length | Req | Repeat | Table # | Description |
|---|---|---|---|---|---|---|---|
| PEO-1 | Event Identifiers Used | ce | — | R | Y | — | Coded identifiers for this adverse event |
| PEO-2 | Event Symptom/Diagnosis Code | ce | — | O | Y | — | Coded symptom or diagnosis observed |
| PEO-3 | Event Onset Date/Time | ts | — | R | — | — | When the adverse event began |
| PEO-4 | Event Exacerbation Date/Time | ts | — | O | — | — | When the event worsened |
| PEO-5 | Event Improved Date/Time | ts | — | O | — | — | When the event began improving |
| PEO-6 | Event Ended Date/Time | ts | — | O | — | — | When the event fully resolved |
| PEO-7 | Event Location Occurred Address | xad | — | O | Y | — | Address where the event took place |
| PEO-8 | Event Qualification | id | — | O | Y | HL70237 | Classifies the nature of the event |
| PEO-9 | Event Serious | id | — | O | — | HL70238 | Indicates whether the event was serious |
| PEO-10 | Event Expected | id | — | O | — | HL70239 | Whether the event was anticipated |
| PEO-11 | Event Outcome | id | — | O | Y | HL70240 | Clinical outcome of the event |
| PEO-12 | Patient Outcome | id | — | O | — | HL70241 | Overall outcome for the patient |
| PEO-13 | Event Description From Others | ft | — | O | Y | — | Narrative from third-party witnesses |
| PEO-14 | Event From Original Reporter | ft | — | O | Y | — | Narrative from the initial reporter |
| PEO-15 | Event Description From Patient | ft | — | O | Y | — | Narrative supplied by the patient |
| PEO-16 | Event Description From Practitioner | ft | — | O | Y | — | Narrative from treating clinician |
| PEO-17 | Event Description From Autopsy | ft | — | O | Y | — | Findings sourced from autopsy report |
| PEO-18 | Cause Of Death | ce | — | O | Y | — | Coded cause of death if applicable |
| PEO-19 | Primary Observer Name | xpn | — | O | Y | — | Name of the primary observer |
| PEO-20 | Primary Observer Address | xad | — | O | Y | — | Postal address of the primary observer |
| PEO-21 | Primary Observer Telephone | xtn | — | O | Y | — | Contact telephone for the observer |
| PEO-22 | Primary Observer's Qualification | id | — | O | — | HL70242 | Professional qualification of observer |
| PEO-23 | Confirmation Provided By | id | — | O | — | HL70243 | Who confirmed the event report |
| PEO-24 | Primary Observer Aware Date/Time | ts | — | O | — | — | When the observer first became aware |
| PEO-25 | Primary Observer's Identity May Be Divulged | id | — | O | — | HL70243 | Consent flag for sharing observer identity |
Examples
Minimal
A PEO with just the two required fields — event identifier and onset date/time.
PEO|AE-2024-0517^Adverse Event^L|||20260412103000
Fully populated
PEO|AE-2026-7741^Severe Hypotension^L|R55^Syncope^I10|20260601084500|20260601090000|20260601094500|20260601110000|22 Linden Ave^^Riverford^OH^45402^USA|A|Y|N|R|R|Witnessed by partner on waking|Patient collapsed shortly after dose|I felt dizzy and woke on the floor|Vitals normal on arrival, BP 78/40|||Adekoya^Tomi^J^^Dr.|140 Clinic Way^^Riverford^OH^45402^USA|^WPN^PH^^^937^5550199|P|P|20260601090500|Y
Annotated breakdown
PEO
|AE-2026-7741^Severe Hypotension^L PEO-1 Event identifier (required)
|R55^Syncope^I10 PEO-2 Symptom/diagnosis code
|20260601084500 PEO-3 Onset date/time (required)
|20260601090000 PEO-4 Exacerbation date/time
|20260601094500 PEO-5 Improved date/time
|20260601110000 PEO-6 Ended date/time
|22 Linden Ave^^Riverford^OH^45402 PEO-7 Event location
|A PEO-8 Event qualification (Adverse)
|Y PEO-9 Event serious
|N PEO-10 Event expected
|R PEO-11 Event outcome (Recovered)
|R PEO-12 Patient outcome (Recovered)
|Witnessed by partner on waking PEO-13 Description from others
|Patient collapsed shortly after... PEO-14 From original reporter
|I felt dizzy and woke on the floor PEO-15 From patient
|Vitals normal on arrival... PEO-16 From practitioner
| PEO-17 From autopsy (n/a)
| PEO-18 Cause of death (n/a)
|Adekoya^Tomi^J^^Dr. PEO-19 Primary observer name
|140 Clinic Way^^Riverford^OH^45402 PEO-20 Primary observer address
|^WPN^PH^^^937^5550199 PEO-21 Primary observer phone
|P PEO-22 Observer qualification (Physician)
|P PEO-23 Confirmation provided by
|20260601090500 PEO-24 Observer aware date/time
|Y PEO-25 Identity may be divulged
In context — PEX message excerpt 1
A PEX report for a serious cardiovascular event observed after administration of a marketed cardiac drug.
MSH|^~&|MEDWATCH|CLINIC-OH|FDA-AERS|FDA|20260601120000||PEX^P07^PEX_P07|MSG00012741|P|2.5.1
EVN|P07|20260601120000
PID|1||PT-44871^^^CLINIC-OH^MR||Okafor^Adaeze^M||19620318|F
PES|Riverford Cardiology^^L|Adekoya^Tomi^J^^Dr.|140 Clinic Way^^Riverford^OH^45402|^WPN^PH^^^937^5550199|SE-2026-7741|1||First report from treating physician|20260601090500|20260601120000|I|P
PEO|AE-2026-7741^Severe Hypotension^L|R55^Syncope^I10|20260601084500||20260601094500|20260601110000||A|Y|N|R|R||Patient collapsed shortly after dose|||||||Adekoya^Tomi^J^^Dr.|||P|P|20260601090500|Y
In context — PEX message excerpt 2
A follow-up PEX report adding autopsy findings to a previously reported fatal event.
MSH|^~&|MEDWATCH|HOSP-CA|FDA-AERS|FDA|20260605143000||PEX^P07^PEX_P07|MSG00012805|P|2.5.1
EVN|P07|20260605143000
PID|1||PT-90112^^^HOSP-CA^MR||Tremblay^Luc^||19450902|M
PES|Mercier Regional Hospital^^L|Boucher^Marie^^^Dr.|9 Avenue Cartier^^Trois-Rivieres^QC^G8T2X1^CAN|^WPN^PH^^^418^5550144|SE-2026-7805|2|Autopsy results now available||20260604180000|20260605140000|F|P
PEO|AE-2026-7805^Cardiac Arrest^L|I46.9^Cardiac arrest^I10|20260530220000||||35 Rue Hopital^^Trois-Rivieres^QC^G8T2X1^CAN|A|Y|N|D|D||||Massive myocardial infarction on autopsy|Findings consistent with infarct|I21.9^Acute myocardial infarction^I10|Boucher^Marie^^^Dr.|9 Avenue Cartier^^Trois-Rivieres^QC^G8T2X1^CAN|^WPN^PH^^^418^5550144|P|P|20260531080000|Y
Implementation notes
- PEO-1 (Event Identifiers Used) and PEO-3 (Event Onset Date/Time) are the only fields that must be present in a conformant message; senders should still populate seriousness, outcome, and at least one narrative whenever the information is known.
- The five date/time fields (PEO-3 through PEO-6 plus PEO-24) together form the event timeline. Populate them as facts become available rather than defaulting unknowns to the report date.
- Free-text narrative fields (PEO-13 through PEO-17) are repeating to allow multiple paragraphs or supplementary statements. Many regulators prefer one source per field to preserve provenance.
- PEO-25 governs whether the observer's identity may be disclosed downstream; respect this flag when forwarding the message.
Related segments
- PES — identifies the organisation and individual reporting the event.
- PCR — describes the product implicated in the experience.
- PEX message — the trigger event that carries PEO end-to-end.
