We had a pt that had a procedure CPT code 36470 RT, 37765 RT, 76942 dx I83.811 on 10/20/2016. At that time after the doctor talked with the pt they decided that her left leg probably needed treatment as well. We had not performed an ultrasound of that leg or had documentation to warrant treatment of that leg. We scheduled the pt for an US and FU appt on 10/31/2016 so we could send information to her ins co to get approval for another procedure. Our office visit for 10/31/2016 was denied for global. On 10/31/2016 we billed CPT code 99213 dx code M79.605, I83.812. We did not put a modifier. What modifier if any could we use?