The base code for 45385, 45380, 45381 is 45378. You cannot bill 45378 with any other code, hence the "separate procedure" next to the code description.
All the other codes can be billed together, but, you have to make sure you know and understand the breakdown of the colon and its different areas.
If you e.g. perform a 45385 (snare) in the ascending colon, and a bx 45380, in the transverse colon, and finally in the sigmoid colon, an injection, e.g. tattooing, is performed you are allowed to unbundle the 45385 and 45380 procedures with a modifier 59/XS. 45381 is not bundled into 45385 and 45380.
I hope this helps.