Ask Dr. Z

I'm needing some help with understanding proper coding and modifier use within a surgical global period.

Patient has fistula placed (36821) as well as tunneled catheter (36558) placed. Two months later, superfistulization (36832) is performed. Two weeks after that (still within 90-day global period) the tunneled catheter is removed in the office. What would be the proper modifier use in this scenario? Can catheter removal code 36589 be reported within this period in the office setting?

Or in the case where a fistula is placed in the LEFT arm, but fails in two months and a new one is placed in the RIGHT arm within the 90-day global period, would this be reported with modifier -79 because it's different arms or -78 because it's related, but not anticipated?