The spring '91 CPT Assistant says to use -52 for attempted procedures. Here is an excerpt:
"...modifier -52, reduced services, is used to describe a situation when a service or procedure is partially reduced or eliminated at the physician's election. For example, a flexible fiberoptic esophagoscopy was ATTEMPTED and the physician could not complete the entire procedure due to obstruction or other complication, you would report 43200-52 to describe that the procedure was reduced.
Since your procedure is not attempted and scope was inserted into esophagus report 43200 completely.