Parameters within URL that contain a backslash

[AgentK88]

I have an API that I call that accepts parameters for a username e.g. DOMAIN\User.Name. When building the URL which contains the parameter, e.g. https://localhost:8083/api/v2/PatientId/DOMAIN\User.Name, I think the backslash gets converted to a forward slash which then results in a 404 error being returned.

Do you know of any way that a backslash can be passed within the URL as a parameter without any conversion?

I've tried using double backslash. %5C and adding CONTENTTYPE_URLENCODED