This week, snare selection and snaring tips on the ASGE SUTAB tip of the week. A few words about snare selection for polypectomy and EMR. First for cold snaring, I prefer the dedicated cold snares. They have a wire diameter that's reduced by about a third compared to standard snares. So they cut better, they result in a little bit more immediate bleeding. You can use a standard diminutive snare, but you're a little bit more likely to have to pull through tissue. And when you're using these snares, the art of using them is finding the right degree of distention and getting the right amount of tissue so that you can avoid drag and having to mechanically pull through the snare. And those considerations apply both to standard snaring of diminutive and small polyps that have not been injected and to cold EMR. For hot EMR, we want to use stiff snares. The stiffness of the snare helps it to grip the tissue. There's less sliding. And for snare size, we generally should limit the snare size to 15 to 20 millimeters. And the rationale for that is that great big snares are more likely to trap muscle. We see more muscle injuries. I will admit that for very large granular lateral spreading tumors, I usually prefer a 20 millimeter snare. This of course refers to the diameter of the snare. The length of the snare is even longer, but I just find that it's more efficient, especially I think it's safe if the lesion is lifting really well as lots of big granular lesions do. But there are other times where I use a 15 millimeter and I may go back and forth in the same lesion. And to finish up, I typically use a 10 millimeter snare to get those bits around the margin or in the center that have been left behind. Some people will use a cold snare to cut those off. My own tendency is if I start hot, I'll stay hot all the way through. Same with cold. If I start an EMR cold, I'll typically stay cold all the way through the process. For pedunculated polyps, you can choose a snare size that's appropriate for the head. But for the very, very large one, you want a great big snare that's open because you want to try hard to get over the top of the polyp and get down low on the stalk and transect the entire lesion on block. And then for the CAP technique, which we'll discuss in an upcoming video tip, this is a technique that I use to get a hold of flat or fibrotic tissue. You want to use a small snare, typically 10 to 15 millimeters. When people are first starting, I recommend that you use a flexible snare because it has a smoother throw on it. And the snare closure is a blind procedure. So when techs are starting out closing on tissue blindly and feeling when they have grasped the tissue, they can do it easier with that smoother throw of a flexible snare. More experienced technicians can often do it with stiffer snares, but about 15 millimeters is the maximum size that I use for the CAP technique. And again, we're going to come back to that in a future video tip. Returning for a moment to the issue of snare size for hot EMR, I want to discuss a couple of issues that may seem overly simplistic, perhaps obvious, but I think they are important and give my perspective on them. So we mentioned that the recommended snare sizes for hot EMR are 15 to 20 millimeters. The larger the snare is, snares that are bigger than that seem to be associated with a greater risk of muscle injury. I also mentioned that my preference for very large granular lesions that lift well is to use a 20 millimeter snare. And I think that in general, it's safe to do that and to even take quite big pieces. But I want to make the point that even using a very large snare, you can position the snare and show some discretion and take much smaller pieces. And I mentioned this because when I'm teaching fellows EMR, they often have a tendency to open the snare regardless of size and push the tip of the sheath right up against the next piece to be removed and take the biggest piece possible. But we can actually use a big snare, have the flexibility to take big pieces and also the discretion to take smaller pieces if we control the use of the snare. I think this also gets at the broader question of when we're doing traditional EMR, should we try to remove the lesion in the fewest number of pieces possible? Is there value in removing a very large lesion in 15 pieces rather than 25 pieces? And you might think so because we hear so much discussion about the value of on block resection, whether it's by ESD or underwater EMR. But I don't think we can extrapolate any principles to traditional EMR and say that fewer pieces is more valuable than taking the lesion in larger pieces because we have this randomized controlled trial that showed that when you're finished, if you go around and burn up the normal margin with the snare tip on soft coag, we discussed that in the first video tip, you get this very, very low recurrence rate. And that appears to be independent of whether the lesion was removed in fewer versus more pieces. And of course it suggests that the recurrences tend to come in from invisible tissue that's been left at the margin as opposed to the center of the lesion. So I think that it's not critical and we can use a big snare and have the flexibility of getting a big piece when it's really dictated that we should do that by the morphology of the lesion or the way the mound looks and still be able to show discretion with that. And that's the technical point that I want to discuss further. So to demonstrate this principle of snare control, we're going to look here at a granular lesion that starts down in the cecum and extends out into the ascending colon. Now this is a very large lesion and we're taking the first piece off here and we're going to use the approach of filling the entire 20 millimeter snare with tissue. And that's generally safe. Again, when we go to very large size snares, we probably do increase the risk of muscle injury. But this lesion, like most granular lesions, is lifting very well. Now we're going to use the alternative approach, which is rather than just push the sheath up against the tissue and take the biggest piece possible, we're going to place the tip so that we can sort of see the size of the piece that we're going to end up with. And then as the snare closes, we push the sheath forward and end up with a more conservative sized piece. So this large snare gives us the discretion to go around a somewhat more nodular area or a mound that's particularly large and take the whole thing if we feel that that's safe. Or according to our level of experience and comfort, we can place the tip and take somewhat smaller pieces. Because again, the evidence suggests that the critical thing with regard to recurrence is not that we take this out in the minimum number of pieces. Here you can see again, we're showing a little bit of discretion about the size of the piece. One thing is we clearly don't want this patient to go to surgery for a lesion like this that has a very low risk of having cancer in it. And we want to be able to do it safely. So we're showing a little bit of discretion in the size of pieces that we're taking. And then at the end, we're going to rely on snare tip soft coag around the entire margin. That's what the current data suggests is really going to lower the recurrence rate rather than removing it in the fewest number of pieces possible. To demonstrate this a bit further, we have another granular lesion in the ascending colon that we've injected. And notice that we're using the tip of the snare. It's the placement of the tip of the snare that's allowing us to control the size of piece that we remove. This very large snare, we're removing a piece that's considerably smaller than the snare we're already planning that will then take that nodule out separately. And we've got the flexibility to take out a fairly substantial nodule with this 20 millimeter snare. So basically demonstrating that using accurate placement of the snare tip, we can control piece size to a level that we're comfortable with during hot EMR. Next week, the pivot maneuver in snaring on the ASGE SuTab tip of the week.

snare selection

snaring tips

polypectomy

EMR procedures

tissue grip