It is really unfortunate that after this wonderful inservice I have not done GI nursing. No practical use of this knowledge!!!! I'm trying to remember from the class and reviewing my notes....... I am really extrapolating a lot from my memory and notes so don't quote me as any expert.
As the scope is being threaded through the colon... the "tip" of the scope advances, IF the scope starts looping the loop is forming further back, maybe ???? 6 centimeters ???? plus, minus, back from where the tip is. So the purpose of abdominal pressure is to push where the loop might be forming to prevent the scope from looping.
So where the pressure is applied will change as the scope is advanced.
The first trouble spot, around 20 - 30 cm (I know it is hard to know, see, how many cm the scope is in from where you might be standing?) But kind of, sort of, if the scope has not gone in too far and starts looping the loops would be kind of "under the bladder" so you would apply gentle suprapubic pressure on the bladder, pushing with your hands flat on the bladded to prevent the scope from looping.
The second trouble spot would be about 30 - 40 cm the tip of the scope is past the splenic flexure and the scope may be looping in the descending colon, if it starts looping you want to apply a gentle "lifting" of the left lower quadrant (honestly the "lifting" part I don't get, don't remember, exactly what they meant..? apply some posterior pressure also to "lift" the descending towards the patients front???)
The third area, about 50 - 60 cm in, the tip of the scope has passed through the transverse colon and is in the ascending, if the scope starts looping the loops are forming in the transverse colon. You want to apply gentle upwords pushing of the transverse colon to straighten out the natural u shape of the transverse colon. A gentle upwards pressure in the left or mid upper abdomen, towards the patients head.