Should be included in the global for the surgery unless the patient has a condition or conditions that need to be assessed in order to have the surgery. You would use the diagnosis code of the conditions, not the reason for the surgery..for example. A person who will have a knee arthroplasty (replacement) may also have diabetes, a heart condition etc. Code for those, not the reason for the joint replacement as that is why you would be seeing them. And do not use a dx code for clearance for surgery..(probably a Vcode though I am not looking this up).