If the surgery was performed in the ER, then the POS would be the ER.
If the patient went to the OR and you cannot determine whether or note the patient was admitted, they would be considered an outpatient POS.
Of note: Sometimes it is not determined whether or not the patient will be admitted until they are in recovery, so the surgery can/should still be billed as an outpatient. What is their status the moment they are performing the surgery - where are they? should be the defining factor. You also have to be aware of how the hospital bills these POS or your MD may get denied.
