HL7 v2 De-identification¶

OpenMed can redact common PHI-bearing fields in HL7 v2.x pipe-delimited messages while preserving segment order, delimiters, repetitions, components, and subcomponents.

The helper is local and mechanical. It does not run an MLLP listener, validate full conformance profiles, or call network services.

from openmed.interop.hl7v2 import redact_hl7v2

redacted = redact_hl7v2("synthetic_oru.hl7", date_shift_days=31)

Supported Scope¶

The default field map is intended for common ADT, ORU, and ORM message flows. It parses the delimiter set from MSH-1 and MSH-2, then applies rules keyed by segment and field position.

Structured fields use these actions:

• clear: remove the field value.
• hash: replace each leaf value with a deterministic hash token while preserving HL7 delimiters.
• surrogate: generate label-aware fake values while preserving repetitions, components, and subcomponents.
• date-shift: shift every configured date by one consistent offset within the message.

Free-text fields use OpenMed PII de-identification:

• OBX-5 when OBX-2 is TX or FT.
• NTE-3.

Default Field Map¶

The default map includes common direct identifiers in these segments:

Unknown segments pass through unchanged unless you configure a rule for one of their fields.

Extending Rules¶

Pass a replacement field map keyed by either tuples or strings:

from openmed.interop.hl7v2 import DEFAULT_FIELD_MAP, HL7FieldRule, redact_hl7v2

field_map = {
    **DEFAULT_FIELD_MAP,
    "ZNT-2": HL7FieldRule("redact_text"),
    ("ZID", 4): HL7FieldRule("hash", label="ID_NUM"),
}

redacted = redact_hl7v2(message_text, field_map=field_map)

For offline tests, pass a deidentifier callable. The callable should return either a string or an object with deidentified_text.