There is no guidance, per se... I work in an LTCH and we have Interrupted Stays also. We do not require a discharge summary for the first part of the "Interruption" and don't start notifying the provider of the deficiency, until after the 9th day away (pertaining to Medicare Acute Hospital Transfers) Some of our providers wait the 9 days to do the discharge summary just to see if the patient returns. If they do a discharge summary and the patient returns within the 9 day time frame, we don't do anything from an HIM standpoint. However, there could be a billing issue from the provider's side since they can only bill one Discharge Evaluation and Management code (CPT 99238 or 99239) per hospital stay.
Hope this helps..