38 C.F.R. § 17.53
The admission of any patient to a private or public hospital at Department of Veterans Affairs expense will only be authorized if a Department of Veterans Affairs medical center or other Federal facility to which the patient would otherwise be eligible for admission is not feasibly available. A Department of Veterans Affairs facility may be considered as not feasibly available when the urgency of the applicant's medical condition, the relative distance of the travel involved, or the nature of the treatment required makes it necessary or economically advisable to use public or private facilities. In those instances where care in public or private hospitals at Department of Veterans Affairs expense is authorized because a Department of Veterans Affairs or other Federal facility was not feasibly available, as defined in this section, the authorization will be continued after admission only for the period of time required to stabilize or improve the patient's condition to the extent that further care is no longer required to satisfy the purpose for which it was initiated.
38 C.F.R. §17.53