Question: Arizona Subscriber Answer: You should not use modifier 25 (Significant, separately identifiable evaluation and management service by the same physician on the same day of the procedure or other service) on an E/M code (such as 99201-99215, Office or other outpatient visit for the evaluation and management of a new or established patient) when your physician performs an EKG, Protime, or any ultrasound study as part of a pre -or postprocedural workup. Some carriers want you to append modifier 25 onto your E/M code (such as 99201-99215) when the cardiologist performs an EKG (such as 93000, Electrocardiogram, routine ECG with at least 12 leads; with interpretation and report) in diagnostic cases.