In the You Be the Coder item in Otolaryngology Coding Alert vol. 11, no. 2, we said: Youll want to append modifier 25 to 31231 (Nasal endoscopy, diagnostic, unilateral or bilateral [separate procedure]) because that procedure has zero global days. We should have said: Youll want to append modifier 25 to the E/M that accompanies 31231 (Nasal endoscopy, diagnostic, unilateral or bilateral [separate procedure]) because that procedure has zero global days. Key points: Neither the 25 modifier or the 57 modifier ever is attached to a procedure or service.They are only attached to an E/M code. Assuming that a significant, separately identifiable E/M (for instance, 99213, Office or other outpatient visit for the evaluation and management of an established patient, which requires at least 2 of these 3 key components: An expanded problem focused history; An expanded problem focused examination; Medical decision making of low complexity. &) was documented with 31231, the services would be billed 99213-25, 31231. If your ENT documented signs and symptoms such as 784.0 (Headache), attach those diagnosis to the E/M and attach the definitive diagnoses from the nasal endoscopy, such as 473.9 (Unspecified sinusitis [chronic]), to the nasal endoscopy.