I do an eval and state that the patient does not present with signs and symptoms of WHATEVER the Dr's DIAGNOSIS IS. For example, I had a patient referred to us for Hip bursitis. No swelling was noted, no pain with palpation over greater trochanter. All tests for trochanteric bursitis were negative. From here, you can either end up with your own different diagnosis or if you did not find anything you as a PT can help the patient with, you send the patient back to the doctor or /and refer to another specialist, and /or suggest specific tests ( x ray, MRI, etc).