A virtual colonoscopy is doing a colonoscopy with an x-ray machine. Instead of a physician, a gastroenterologist using an instrument to go up into a colon, there's no instrument involved ...

During a colonoscopy, if abnormal growths ... During the procedure, the doctor puts a tube-like instrument called a colonoscope into your rectum. It’s long but only about a half-inch across.

They involve inserting specialized instruments or tools into the digestive system, either through the mouth or the anus.