We have a psychiatric unit which needs a psychiatric diagnosis in order to meet medical necessity for the stay. When the patient's final diagnosis is dementia with behavioral disturbance due to Parkinson's Disease, we are directed to code the manifestation first. We submitted the bill to the insurance carrier with the G20 first then the dementia code F039. One of our insurance carriers has denied the claim because they want the psych diagnosis first. But our coding guidelines tell us to code the medical manifestation first. Have you come across this issue? How do we handle this? Are we able to flip the order of these codes?