I am not sure what constitutes "general anesthesia". For my biopsy I had an IV injection that someone described as "super valium". I gently went to sleep and then woke up after the procedure. This is the same thing that was used on me during the four colonoscopies that I have had. They were all administered by a 'nurse' technician.
So maybe the doctor overspoke, as I consider general anesthesia more like what was used during my surgery. I remember that a doctor who identified himself as the head of anesthesiology did the work during surgery, so I assumed it was different. Same result though, went to sleep ...woke up...
My brother had only a local anesthesia during his biopsy and complained of some discomfort.