42 C.F.R. § 424.106
(a) Basic requirement.
(b) Factors that are considered. CMS considers the following factors in determining whether a nonparticipating hospital in a rural area meets the accessibility requirements:
(5) Any other factors that bear on whether or not the services could be provided sooner in the nonparticipating hospitals than in a participating hospital in the general area.
In urban and suburban areas where both participating and nonparticipating hospitals are similarly available, CMS presumes that the services could have been provided in a participating hospital unless clear and convincing evidence shows that there was a medical or practical need to use the nonparticipating hospital.
(c) Factors that are not considered. CMS gives no consideration to the following factors in determining whether the nonparticipating hospital was the most accessible hospital:
(d) Conditions under which the accessibility requirement is met. If a beneficiary must be taken to a hospital immediately for required diagnosis and treatment, the nonparticipating hospital meets the accessibility requirement if—