Thank you for your inquiry regarding the acceptable reporting of patient sex. In cases where the patient’s phenotypic birth sex is not documented/available in the EHR, it is acceptable to use administrative sex if required by the measure logic. The measures referenced in your inquiry (CMS124; CMS125; CMS153) restrict the initial population to ‘Female’ using the AdministrativeGender code system with value set ‘Female’ (2.16.840.1.113883.3.560.100.2): exists ( ["Patient Characteristic Sex": "Female"] )   It is also acceptable to use administrative sex for the ‘Supplemental Data Elements’ section of the measures; specifically data element ‘SDE Sex’, which uses the ‘ONC Administrative Sex’ value set (2.16.840.1.113762.1.4.1) with the same AdministrativeGender code system as noted above. It is important to note that even though the value set for ONC Administrative Sex is limited to response options ‘Male’ and ‘Female’, it allows for the use of the HL7 V3 NullFlavor code ‘UNK (“Unknown”)’ to satisfy ONC’s 2015 Edition EHR Certification Requirements for recording birth sex ( https://www.federalregister.gov/documents/2015/10/16/2015-25597/2015-edition-health-information-technology-health-it-certification-criteria-2015-edition-base#p-220 ). For updated information on representing patient sex at birth, please also see https://www.healthit.gov/isa/representing-patient-sex-birth .   As you alluded to in your inquiry, these requirements mandate the use of these values for recording patient sex at birth and have been used to represent sex in administrative data as well. Therefore, evaluating administrative sex as the biological phenotypic sex would be acceptable. Please note that several activities are currently underway to re-evaluate the requirements specific to the collection of patient gender and sex. As this work is finalized, CMS may alter the guidance provided in this response for future measure periods.