HL7 Cross Paradigm Implementation Guide: Gender Harmony - Sex and Gender Representation, Edition 1
1.0.0 - release

HL7 Cross Paradigm Implementation Guide: Gender Harmony - Sex and Gender Representation, Edition 1, published by HL7 Terminology Infrastruture Work Group. This is not an authorized publication; it is the continuous build for version 1.0.0. This version is based on the current content of https://github.com/HL7/fhir-gender-harmony/ and changes regularly. See the Directory of published versions

External Standards


The existing DICOM (Digital Imaging and Communications in Medicine) model dates back to 1985 and earlier work. It was frozen and has remained unchanged since 1995. Imaging medical records from 1995 onward all use this model. The DICOM model was originally specified to include a single mandatory field to capture Patient’s Sex (0010,0008) with allowed values of Male, Female, Other and Unknown. Initially, the usage was not explicitly specified. It can be used in various places within DICOM, and by DICOM compliant equipment, to specify values for sex-linked characteristics. For example, it is used as input for Standard Update Value (SUV) computations in nuclear medicine and used as a parameter into patient dose sensitivity models for radiation dose reporting. These computations and models are based on statistical analysis of many patients and reflect the sex-linked characteristics of the studied populations.

Operationally, this field is initially populated either by hand or based on an order. The order is frequently conveyed by HL7 V2.x message. The inconsistency and confusion caused by having one field for multiple concepts (administrative sex, gender identity and sex parameter for clinical use) leads to occasional inconsistency in the image results and reports created by DICOM equipment. It also leads to operators occasionally making changes to reflect the patient’s sex parameter for clinical use that then cause downstream inconsistencies with other systems that were using administrative sex or gender identity.

DICOM Change Process

At time of publication of this Implementation Guide, DICOM has a supplement, “Supplement 233, Patient Model Gender Enhancements” in process to incorporate some of the changes from the HL7 Gender Harmony Project. The present expectation is to revise DICOM to:

  • Clarify that the current Patient Sex attribute corresponds to the originator’s administrative choices. This preserves compatibility with existing medical records archives and equipment. It also explains that SPCU should be used for clinical analysis when available.

  • Add an optional SPCU attribute to convey SPCU as defined in the logical model. As gender harmonized applications are installed upstream that support SPCU, this should reduce ambiguities resulting from the use of local administrative choices.

  • Add an optional Patient Gender Identity attribute with the same required and optional value set as described here.

  • Add an optional Name to Use attribute.

  • Add an optional Pronouns attribute.

  • Add an optional Recorded Sex and Gender attribute.

  • Clarify existing DICOM patient and order comment fields to indicate that when Sex Parameter for Clinical Use is “Specified”, these comment fields should provide information explaining relevant information for operators and clinicians. They are presently used for operator instructions, so this usage is a continuation of current usage.

These meet the strategic constraints on DICOM that the existing medical archives must remain valid without modification, that existing medical devices must remain minimally compliant, and that systems can be upgraded to fully support these changes without introducing dependency on upgrading other equipment.

DICOM is coordinating the development and approval of this change proposal with the activity of the Gender Harmony project.


Logical Observation Identifiers Names and Codes (LOINC) is “the international standard for identifying health measurements, observations, and documents.” LOINC is released twice a year (February and August) under Creative Commons Attribution 4.0 International Public License. Gender harmony project uses LOINC clinical identifiers to represent the following observations:

  • Gender identity (GI): 76691-5
  • Sex parameter for clinical use (SPCU): 99501-9
  • Recorded sex or gender (RSG): 99502-7
    • The LOINC set of example answer values is provided as just an example set by LOINC and while useful, is not intended to be a required implementation.
  • Personal pronouns - Reported: 90778-2
  • LOINC does not have an observable that specifically represents a person’s chosen name to use.

All of the above observations align directly with the gender harmony content.

In addition to the above, LOINC also includes the useful observation Sexual orientation (76690-7).


The National Council for Prescription Drug Programs (NCPDP) is an ANSI-accredited SDO representing the pharmacy services industry. The NCPDP SCRIPT ERx standard is used in EHR systems. The current values under the standard, labeled Gender, are F (Female), M (Male), and U (Unknown).

However, NCPDP is moving to include both Administrative Gender and Sex at Birth elements in its future state. NCPDP has identified a business need to identify when someone’s gender is different then their Sex Assigned at Birth (SAAB) to obtain medication without delay, in situations where gender mismatch edits may occur.

Currently, NCPDP has approved the field Sex Assigned at Birth that will be used as an optional field in the event the Sex Assigned at Birth (if present) differs from the current XML element Gender. For example, the Sex Assigned at Birth could be “Male” with the Gender field “Female”.

Note: The NCPDP Gender Transition Task Group determined the Conditional Gender Code (C08- 4T), and Purchaser Gender Code (595-YY) were not applicable to patient matching. There was also an added element of “Reproductive Potential”.

SNOMED International

SNOMED International produces and maintains SNOMED CT, a globally recognized and used terminology standard for electronic health data. In 2021, a group of subject matter experts were gathered to participate in a Sex and Gender Clinical Project Group to provide advice on sex and gender terminology requirements for health record data. The group was closed in May 2021, pending the results of the ISO TC215 (Health Informatics) WG3.

As a consensus standard that strives to align with international standards groups working in the same domain, SNOMED International will participate with ISO TC215 WG3 in their efforts in this domain to ensure international alignment.

SNOMED International recognizes that there may be omissions, outdated or erroneous content in the disorders and procedure hierarchies related to sex and gender in SNOMED CT and encourages submissions of content requests for change through the appropriate National Release Centers (NRCs).


X12 is an ANSI-accredited Standards Developer (ASD) that develops and maintains business-to-business data exchange standards, including electronic data interchange (EDI) standards and schemas, which drive business processes globally. With more than 320 transaction standards available for use, X12 standards are used to conduct nearly every facet of business-to-business operations.

X12 is actively participating in HL7’s Gender Harmony Project and intends to present recommendations based on the group’s findings to X12’s members. Currently, X12 transactions include gender codes from an X12 maintained list identified as data element 1068 - Gender Code. Data element (DE) 1068 is a set of codes indicating the sex of an individual. The X12 EDI Standard version 008030 supports the following codes for use in DE 1068.

  • A – Not Provided
  • B – Not Applicable
  • F – Female
  • I – Nonbinary
  • M – Male
  • N – Non-sexed
    Gender is not known because observation or examination for such was not recorded or requested by the protocol
  • T – Self-reported as Transgender
  • U – Unknown
  • X – Unsexable
    Gender could not be determined because of ambiguity in external or internal genitalia