EMR on the ASGE SuTab tip of the week. Over the past couple of weeks, we've discussed the use of prophylactic clip closure of certain EMR defects to prevent delayed hemorrhage. A more important and immediate use of clip closure is in the case of muscle injury during EMR. This is Michael Burke's classification of muscle injury. Type one is exposure of the muscle. We don't necessarily have to clip reinforce the muscle in this instance, but if there's been a chance of thermal injury to the muscle, it should be considered. Type two, loss of the subucosal plane. We certainly should consider reinforcement of the wall with clip closure if there's been a risk of thermal injury to the muscle. Then type three through five, three being muscle cut without perforation and types four and five, perforation without and with contamination. We absolutely must close the defect during the procedure. These are factors sometimes cited to increase the risk of muscle injury. One is using large snares on non-penunculated lesions. The recommendation has been made to limit snare size to 15 to 20 millimeters. Don't be too greedy. Location of the cecum or transverse colon. Respect the transverse colon in this regard. Prior partial resection, biopsy or tattoo, especially I think if tattoos have been made with the injection directly under the lesion and increases the risk of fibrosis and muscle injury. Anecdotally, my own sense is that using cutting current is more likely to go through the muscle without any sense of resistance that you might feel with forced coag current. And then large nodules or 1S lesions, perhaps just because of their size. There are several ways to close muscle injuries during EMR. I prefer hemostatic clips if feasible, which it typically is unless there's marked fibrosis. There are a couple of reasons that they work well. One is that these muscle injuries are typically quite small. So hemostatic clips are sufficient. I've not seen them fail for type three through five muscle injury. And second, you don't have to change scopes, re-intubate, refine the defect. You keep the injury directly in view. That's a real advantage if there's actual perforation type four or five muscle injury. Before we can fix muscle injuries during EMR, we must learn to recognize them. And this is where the blue contrast in the submucosal injectate is critical in inject and resect EMR. We've discussed before that for serrated lesions, this blue contrast is nice for delineating the margin of the lesions. But in all inject and resect EMR employing electrocautery, the real advantage of this blue contrast is allowing us to identify muscle injury. This contrast stains the submucosa blue, but it doesn't stain the muscle. The color of the muscle is white. So here is an EMR defect with a nice blue stain on the submucosa, and there's no muscle injury here. But you'll notice that there are some fine, lacy white strands. This is fibrous connective tissue in the submucosa. We'll learn to differentiate that from muscle because it's very thin and lacy compared to cut muscle where we'll see thick white bands. Here's the same picture, and I've drawn yellow lines adjacent to some of these wispy white strands of submucosal connective tissue. Again, this is normal. There's no muscle injury here. It's normal to see these submucosal strands in an overall blue defect. And we'll learn to differentiate this from muscle injury, which typically appears as two short parallel bands of considerably thicker white tissue. Here's a typical type one muscle injury after EMR. This was an on-block EMR of a lesion about 20 millimeters in size. You can see the blue area, that is the normal stained submucosa. The white circle at the bottom of the defect, that is exposed circular muscle. Now this muscle has been exposed, but not cut. What we don't know is whether there might be some thermal injury to the muscle. And so I'm pretty cautious, careful, conservative. So type one and two muscle injuries, my tendency is to clip reinforce the wall. This is a proximal ascending colon lesion, a granular lateral spreading tumor near the ileocecal valve. It's about to develop a type three muscle injury where the muscle is cut, but not perforated. So there's the first piece that looks fine. I will acknowledge that the next piece we're taking is a pretty big piece. And perhaps the lesson here is to not be too greedy. Having said that, I will say that most of the time when this has occurred over the course of my career, I've been sort of caught by, surprised by it. My own incidence is less than 1%. The Australian group reported about 3% overall type three through five injury. The two thick white bands there are the cut muscle. Here we've got arrows on these cut bands of muscles so that you can see them clearly. When you get this, you can still finish the EMR. You should be careful about gas insufflation, but before you leave, gotta close that defect with clips. The cut muscle on the base of the EMR defect is often referred to as the target sign. Now, of course, the muscle that was cut is on the specimen. So if we flip the specimen over here, you can see it in the cecum. And after it's been removed and out on the table, the cut muscle will usually appear as a circle of white and it's got arrows on it there. And that's also referred to as the target sign. This is the target sign on the specimen. Here's a 1S lesion about 25 millimeters near the ileocecal valve, has a tattoo under it. I consider this a higher risk lesion for muscle injury because there's a natural tendency with 1S lesions to remove them on block, actually injected it and went underwater. Despite that cut the muscle, the arrows are on the cut muscle. Rather than the usual blue, you can see the submucosa is black from the prior tattoo. Closing these, I typically put the clips right next to each other. And then before leaving, go proximal to the clips and bend them distally to make sure the closure looks good from the proximal side. Then you're done. That's a reliable closure. There's the specimen sitting in the colon. You can see the tattoo in the submucosa and the target sign, the cut muscle on the base of the specimen. A recommendation you often hear is that if you have a large piece of tissue in the snare to squeeze it tightly and then open the snare back up. The idea being that if you had some muscular appropriate trapped in there, when you reopen, gives it a chance to slip back out, then close back down and transect. I don't know how often that really works. Here's an example where it didn't work. In a second, you're going to see that we've cut the muscle. I would have to say that, although we talked about some different risk factors for this, my own incidence of type three or higher muscle injury during EMR has been a little bit lower than 1% over the years. And I found it very hard to predict when it's going to occur. I think the key thing is to look for it on a regular basis, to be ready to fix it. You can either fix it after you've completed the EMR. In this case, we put one clip on because the injury was kind of deep, but you want to place two or three clips over that injury that are closely spaced together to make sure that you've got it sealed. That's very effective in preventing a delayed perforation. If you want then to prevent delayed hemorrhage, you can close the rest of the defect with clips, but a few tightly spaced clips will prevent delayed perforation from type three injury. Next week, closing type four and five muscle injuries that occur during EMR on the ASGE SuTab tip of the week.

clip closure

muscle injury

EMR

Endoscopic Mucosal Resection

Michael Burke's classification