If an emergency or urgent care situation arises, can an “opt out” physician on the “on call” list treat the Medicare patient

“Opt out” physicians should not be listed on the “on call” list for Medicare patients since they are not billing the Medicare program. In rare circumstances, if the “opt out’ physician or practitioner provided emergency care in the hospital emergency room and the critical situation continued after admission to the Intensive Care Unit (ICU) or Critical Care Unit (CCU), she/he could continue to care for the patient until it was no longer urgent.