Today, finding EMR scars on the ASGE SUTAB tip of the week. Before discussing the evaluation of EMR scars, I want to talk about just finding them, which probably seems overly simplistic, but my experience with fellows suggests that it can be difficult for endoscopists to locate EMR scars. Now it's easy if there are still attached clips, and in our experience, about 10% of the time at six months, there's still a clip on the site. It's more common with large clips than with small clips, or if there's a prominent form of clip artifact. So clip artifact refers to mucosal distortion that persists after the clip comes off, and we're going to come back to that. But about two thirds of the time, there isn't any clip artifact, even when clips are used. And of course, if you didn't clip because you did cold EMR because the lesion was in the left colon, then you would expect the scar to be smooth. And so how do we find it? So the first step is to open the original EMR report and study it. In particular, if there's a tattoo, does it specify where the tattoo is in relation to the scars? The tattoo proximal or distal to the site? Is it to the right or the left? If I'm tattooing, we'll usually say with the lesion down, the tattoo was placed to the left. Because if the lesion is up, then the tattoo will be on the opposite side. But you want, ideally, to see the location of the tattoo if one is present. How detailed are the photos? And I would refer you to this recent study from Michael Burke's group in which about 90% of the lesions had no tattoo, yet they found 99.7% of the scars, basically always if the prep was good, they were able to find the scar. And their primary mechanism was just looking at the photograph. So if there are several photographs that show the relationship of the EMR site to landmarks like the ileocecal valve to the adjacent haustral folds, that can greatly facilitate it. And also the detail in the language, sometimes saying that the EMR site is four folds distal to the ileocecal valve on the opposite wall, that type of language is helpful, or it's in the sig white at 32 centimeters from the external verge. Next, when you're looking for it, you want to extend the colon fully, which we'll demonstrate in to look for disruption of normal fold structures. Here's an EMR scar seen at six months after a resection, and this lesion is in the proximal ascending colon opposite the ileocecal valve. Language to that effect in the original report, here it is. It's one to two folds distal to the ileocecal valve on the opposite wall. That would be of great value in identifying the scar. To make sure we're looking at the same area, that we're all looking at the scar, I've outlined it in this picture. It's the white pale area within the yellow line. And the first point I want to make as we look at this scar, again, this pale white area, is that it's best seen when the colon is well distended with gas. What we're doing right now is deflating the lumen, and as we do that, you see that that color discrepancy between the scar itself, that whitish pale color, and the surrounding normal mucosa disappears. Now we're starting to inflate it again, and you're going to see it come back. It becomes more obvious. So this makes the point that when you're hunting for scars that may be subtle, you really want to have the colon well distended. If it's either deflated, not a lot of gas in the lumen, or if you're underwater, because the colon wall just relaxes when you're underwater, you're not going to find scars as easily. So to see scars, distend the colon. Here's another right colon EMR scar at six months. Here the yellow line roughly marks the borders of the scar. So just to demonstrate the importance of distension one more time, let's look at this scar with deflation. Right now, the colon is still distended. You can still see that nice color differential, the pale white color of the scar, but now you can see that the lumen is being deflated, and as that occurs, we're seeing that color differential between the scar and the surrounding mucosa disappear. Now if you already knew that the scar was there, perhaps you could still tell it, but if you didn't, I think it would be very hard at this point to identify the scar, and then as we start to reinflate, you can see gas entering the colon. The colon is becoming distended again. That color differential is starting to reappear, the pale white color. So distension is just really important in the identification of scars. Another tool that is useful for identifying EMR scars, and this is true in both the colon and in the small intestine, is disruption of the normal structure of the folds by the scar. In this instance, there is a red area in the lower right that is a cold snaring defect from a polyp I just took out with a cold snare, but the scar is on the left-hand side of the image. It goes from about 7 o'clock up to around 3 o'clock, and what we want to look at here is the value of recognizing disruption of the fold pattern for seeing the scar. So again, the scar is on the left. The yellow line is along the scar, and then the two yellow marks at the end are the edges of the scar, and the green arrows are on a set of folds that are going from right to left across the bottom of the picture, and you'll notice that when they hit that yellow line, they just abruptly stop, and that, of course, is not normal. You could consider that these are like converging folds, the same sort of thing we see in the stomach after the healing of a gastric ulcer. In the small bowel, it's often very obvious after EMR because except for around the papilla, the valvular coniventae, the plique circularis, whatever you want to call them, they are circumferential consistently, and so when you see disruption of that pattern, then we have to recognize that that is abnormal, and that's going to help and signal the presence of the scar. I want to make the point that these changes in the fold shape can be very subtle. Here is an EMR scar, this thin white line along the bottom, and we've got the colon adequately distended. You can see the fingers of the endocuff vision, and we're looking up at the right-hand edge, and now we're going to pass over toward the left edge of the scar. Looking at the left-hand edge of this EMR scar in MBI, that little orangish-red thing is the tip of one of the endocuff vision fingers. They look that color in blue light, and the green arrows are on a fold extending from left to right, and at the point of the yellow arrows, that fold abruptly stops, and that's where the scar ends or begins, so that's much more subtle than the last case, but it's important to learn to recognize that that kind of change in a fold shape is not normally seen in the colon. It reflects that there probably is scarring present, so learning to recognize these very subtle changes in folds that result from scarring will help to recognize where the scar is, and in this case, it's the left-hand margin. It's the extent of the scar also. One more case to demonstrate these principles. First of all, we look at the old report, which tells us that the EMR was performed near the ileocecal valve. You'll see the valve for a second. It's just ahead of the fold that we're looking at, so we're in the right vicinity. Now we've got to get distended. The scar is going from about 11 o'clock on the left down to about 7 o'clock, and as we get more distension, we can see that slight pale color change, and also we see the deformity of folds at the top edge and the bottom edge, so all of the principles we're using to find one of the major focuses of our follow-up, which is to identify the scar and inspect it for recurrence. Here's a photo of that same scar with yellow lines on the scar and marking the two edges or ends of the scar, and notice again that transition in the shape of that fold when it hits the edge of the scar. There's a subtle dip there, a transition that's not natural. That kind of change signals to us it's an extra signal of the presence of the scar. It also defines the extent or edges, borders of the scar. When we do our EMR follow-ups, we have two important goals. One is to clear the colon of synchronous disease. As we've discussed, there's a very high prevalence of synchronous disease, including serious synchronous disease in patients with large non-pedunculated polyps, and we may not have had enough time to clear the colon at the original EMR, and even if we did, it's good to take a second look in these patients. The other one that's fundamental is to find that scar and examine it for recurrence. To do that, we're going to look carefully at the original EMR report and get as much information about the part of the colon that it's in and what the nearby colon looks like. During the procedure, we're going to distend the colon fully and then look for disruption of the normal fold structures that help to signal the presence of a scar and delineate the margins of that scar. Next week, clip artifact on the ASGE SuTab tip of the week.

endoscopists

EMR scars

clip artifact

EMR report

distending the colon