preventive medicine help

We are having some confusion in our office. If a patient comes in for a "physical" we use the 99381-99397 codes. However if the patient does not really need a physical and the doctor does not "review all systems" and there is nothing wrong with the patient how should this be coded. The only dx would be physical. We want to make sure we don't get audited for charging a physical when it wasn't done. If we charge a E/M code with V70.0 the patient will probably get a bill and say they were in for a physical. Confusing sorry?
Sorry also, we have OBGYN doctors that will see patients for Pap/Breast exam and charge 99381-99397 for the visit and than the patient also see's FP for "physical" on a different day and they charge a physical any ideas on how to handle this? It appears sometimes they both do a physical and sometimes not. Thank you for any help.