According to the CPT 2008 manual a nurse eval (99211) can be billed for : office or other outpatient visit for the evaluation and managment of an established patient, that may not require the presence of a physician. Usually the presenting problems are minimal. Typically, 5 minutes are spent performing or supervising these services.
I know in my OBGYN's office if I have to come in for a minor problem such as needing to get a medication change or the nurse had to spend anytime with me they charge a nurse eval and they have a sign up in the front office letting you know that you may be charged a nurse eval for speaking with the nurse for certain reasons. So if a patients comes in for lab results that could have been given over the phone but they prefer to speak with a person face to face then they will be charged a nurse eval.