In order for an insurance carrier to cover and pay for supplies and/or equipment, medical necessity must be validated from the patient's medical history. This means when an ordering provider prescribes an item, they should also be noting it in their chart with a reason why. For example, a patient needs a blood pressure monitor for home use. The doctor should 1) write a prescription for the blood pressure monitor 2) note in the patients chart they prescribed a blood pressure monitor due to their high blood pressure, etc which requires monitoring. Your medical records provide context (ie reason for medical necessity) for the item the physician prescribed/ordered.