GAO Reviewed Pathology Self Referral in 2013

 https://www.gao.gov/assets/660/655442.pdf

GAO reviewed pathology self-referral in 2013.  At first, I thought, this was about pathologists ordering tests to complete a service, an odd exemption in Medicare law that has never been very explicitly defined.  (If you think you see TB bacilli, you can order a TB stain.   I don't think, if you see breast cancer, you can order an Oncotype Dx test.  However, the point is, the gray zone isn't well-defined in regulations).

However, the report on "self referral" was directly more at e.g. urologists employing (sic) pathologists.  Anyway, it's at the link above.