Wiki PI and PS modifier 78815/78816 subsequent at different facility

[kathleeng]

Question when it comes to billing the same condition as a subsequent scan but for a different practice than the initial scan... do you still append the modifier PS since it's the same condition being followed up on, or does it change due to different facility? Does time ever play a factor? Say patient had initial scan in 2012 but doing subsequent scan in 2021... thoughts? Question pertains to pet scans 78815 and 78816.