Which diathermy setting?
Large polyp at the recto-sigmoid junction on a short stalk which I have pre-injected.
WHICH DIATHERMY SETTING WOULD BE MOST APPROPRIATE?
■ Pure cut, effect level 1
it will bleed like stink !
■ A blended cut, effect level 4
Absolutely, steady does it!
■ Coagulation, effect level 1
Too much heat and too little cutting!
■ Coagulation, effect level 4
WAY too much heat and faaar too little cutting!!!
Endoscopy is an "art" and there is certainly more than one way of resecting polyps. A large polyp (turned out to be a TVA+LGD) could only be sustained by a plentiful supply of blood and therefore immediate bleeding is the most important concern. Removing it piecemeal could reduce the risk of bleeding but would be inappropriate as there is a risk of cancer, nestling deep inside the polyp head.
As you know, I am not a fan of placing clips beforehand. This is polyp is a good illustration why. A few clips on the stalk would get in the way, may lead the current to the nearby colonic wall and are unlikely to compress the vessels DEEP inside that stalk.
The graph above illustrate the four factors which influence the speed of your cut! The most important is the speed of closing the snare, the second is the power setting of your diathermy, the third is the thickness of your snare (thicker, braided snares take longer to cut through a polyp and will impart more heat) and finally the tissue properties (fatty tissue is slower to cut and I guess that a fat patient will require more electricity for the same about of cutting power).
Of course you can decide on the speed of snare closure but closing that snare yourself, or asking your assistant to for example count to 10. By the way, a good tip is to ask your assistant to stop applying pressure on the snare handle when the snare is visibly starting to cut through the stalk. In my experience the 'inertia' in the system will continue the snare closure at the correct speed whilst continuing to close the snare handle often cuts the centre too quickly.
Anyway, this thick stalk could never by cut through with the blue pedal coagulation current. It's simply too thick and you would end up imparting an enormous amount of heat to the tissues. You may consider 'pre-coagulating' the stalk by first applying some coagulation power and then finish with the yellow pedal. It sounds clever but I suspect that the last bit which gets 'cooked' is the centre which carries the vessels. Therefore I hardly ever do it anymore.
A 'pure cut' (called 'AutoCut' by ERBE and 'PureCut' by Olympus would be inappropriate as it would cut the stalk too quickly leading to immediate bleeding. You would only use pure cut setting for sphincterotomy, cutting a short oesophageal stricture etc. This leaves you with the correct answer which is B !