The teaching physician rules define how to bill for services provided jointly by an attending physician and a resident in an accredited Graduate Medical Education (GME) program. Each type of service has a different set of rules that define the level of the the attending physician's participation and the required documentation.
Endoscopy services require that the attending physician be physically present from the start to the end of the procedure: scope in to scope out. Watching from another room on video equipment is not sufficient. Endoscopic surgeries are covered under the surgery rules, not these rules.
The Medicare Claims Processing Manual does not describe whether the attending physician him or her self must document their presence, or whether the resident may do so.