ASGE SuTab tip of the week. This tip I'll review my experience with performing difficult colonoscopy, anatomically difficult colons, which is to say prior incomplete colonoscopies by either a gastroenterologist or a surgeon. So we have more than 940 referrals to this. The last time I looked at the literature, this was about half the published cases in the literature. The success rate in this group of anatomically difficult colons, 97.3%. And this is with no use of balloon endoscopes. And in fact, that success rate compares quite well to the average reported success rate with balloon endoscopes, which is about 95%. We have reported recently that when patients have had an incomplete colon followed up by BE and CTC, and then we look at our colonoscopy as the gold standard for what is there, that the sensitivity of both of those tests for polyps is extremely low. And my own advice is that if you have an incomplete colonoscopy, that you should either repeat it yourself or have somebody that you trust repeat it rather than send the patient to radiographic testing if the fundamental issue that you're dealing with is polyp detection, that is screening, surveillance, diagnostic exams. If the question is colorectal cancer, we don't have enough cases to know if CTC and BE are adequate. These are the key publications from our center on this topic, which included a description of the basic strategy and technique that I'll describe in the video tip, as well as the impact of water filling and redundant colons and the yield of neoplasia. And finally, the recent paper on the sensitivity of BE and CTC after incomplete colonoscopy. Just to focus for a moment on the sensitivity of BE and colonoscopy after incomplete colonoscopy in our series. I can see that in our experience where CTC and BE were performed after incomplete colonoscopy in community centers around central Indiana, that the sensitivity on a per patient basis of CTC and BE were 70% and 27% and a per polyp basis were 24% and 7.6%. And this is not only for small polyps. It gets no better when you look at lesions over 10 millimeters in size or over 20 millimeters in size. Only one cancer in this series, I suppose most of the cancers that were detected never actually came to us. But the one cancer that we detected in the right colon that was beyond the extent of the previous exam was not visualized by CTC. And I think many of the same anatomic problems that plague us in these patients, very difficult sigmoids and very redundant colons can impede filling of the colon with barium, with gas. And this is part of the reason why the sensitivity is poor in this population of patients. And part of the reason why I say that the best approach in these patients may be to repeat the colonoscopy yourself using the techniques that we'll describe in this video or refer the patient to a center, another endoscopist that has experience with colonoscopy in these patients. For these difficult colons, the first step is to classify the anatomic problem. And there are three types. Hernias at the bottom of the slide are the least common by far and I'll dispense with those in a moment. So overwhelmingly in terms of referrals, the colon is either redundant, it's so long that when you get over to the right colon, the referring doctor runs out of scope before they can get down to the cecum or it's a terrible and angulated sigmoid. And the value of classifying the anatomy as either redundant colon or narrowed or angulated sigmoid is that it gets you first to choose the right scope and then secondly, the general right approach. In redundant colons, we're gonna choose adult standard scopes. Many people will choose pediatric scopes no matter what the cause anatomically, but pediatric scopes, the more flexible, the thinner the scope, the more bowing and looping you'll have and what we wanna do in a redundant colon is to prevent that and resist it from occurring. So an adult scope is better. We wanna go in underwater and occasionally we'll have to resort to and over to, but a narrow angulated sigmoid, which is overwhelmingly from diverticular disease. I hear people saying that the cause of difficult colonoscopy is often prior hysterectomy, prior pelvic surgery. And I'll give you that if it was a radical hysterectomy, especially if there's been radiation to the pelvis, but in the absence of those standard hysterectomies for experienced people, I don't think it's true that they create a significant obstacle to CEQL intubation. And these colons, bad diverticular disease, we want a skinnier scope and sometimes we'll need a shorter bending section and we'll also go in underwater. So first to dispense with hernias, which fortunately are a very small percentage of the referrals to my own practice for incomplete colonoscopy. And I'm glad of that because they account disproportionately for the times that we have failed and it's not the left inguinal hernias. They're easy to deal with. You turn the patient on their back, reduce the hernia. Then as you're inserting, have the technician keep a hand over the opening in the abdominal wall. Once you get through the sigmoid, it's no longer a problem. The problem is the transverse colon hernias. These are often in very large people. You can try to reduce them, but it's hard to tell when they're reduced. If you get up to the herniated bowel, you'll enter through a narrowing into the bowel that's in the hernia. And the problem is getting out of the hernia through the opening on the sacral side. If you push hard, you'll get mucosal tears at the anal entrance to the herniated bowel. And in my experience, switching to a thinner scope typically is unhelpful. So I've seen a number of large transverse colon hernias where the only way to perform complete colonoscopy was to have surgical repair of the hernia. So we want to choose the right scope for the redundant colon. This is clearly the adult variable stiffness scope because it resists looping more than thinner scopes do. For the narrowed angulated sigmoid, you need a number of possible scopes. We usually start first with a pediatric colonoscope. However, if the referring doctor is someone that I know and they've already tried a pediatric colonoscope, I often go first directly to the ultra slim or ultra thin colonoscope, the 9.5 millimeter outer diameter. Now that scope has the same length bending section as the pediatric colonoscope. And sometimes you need to have not only a narrow scope, but also something with a shorter bending section that has a tighter turning radius. That can either be an upper scope. The disadvantage of an upper scope is that it only has the length to reach the cecum about two thirds of the time, three fourths of the time requires a lot of abdominal pressure and loop production, or you can use the push enteroscope. I like the SIF-Q 180, which is the thinnest of all these scopes. It's a hair thinner than the upper endoscope and the ultra thin colonoscope. It still has a tight turning radius. The disadvantage of it is the narrow channels. So when you're up working in the proximal colon, sometimes it's hard to get snares, especially through the scope to perform therapeutic procedures. So I'd rather be up in the proximal colon doing therapeutic procedures with an ultra thin colonoscope than with either of these scopes, but sometimes you have to go through them to get through an extremely angulated sigmoid. So this picture shows the tip of the pediatric colonoscope on the left and then the three other scopes that we've been discussing, the ultra thin colonoscope, the upper endoscope and the SIF-Q 180 push enteroscope. And you can see that all three of the scopes on the right, although the diameter is reduced by only a couple of millimeters, that there's an obvious really substantial reduction in the surface area, the tip of the scope. And that's of course, what's really important in getting through a narrowing is the surface area. And you gotta remember that surface area is related to pi R squared. So small reductions in diameter can significantly change the surface area of the tip. And that's what you should think about when trying to get through a narrowing. So I often see in a narrowed, angulated sigmoid that the referring physician has tried a pediatric colonoscope. And I may try that too, but the key is I'm not gonna stop there. If I can't get a pediatric scope through it, I'm gonna go to one of the thinner diameter scopes. Another distinct advantage in an extremely tight angulated sigmoid is the shorter bending section of the upper endoscope and the enteroscope, which are seen on the right compared to the pediatric colonoscope and the ultra thin colonoscope, which have longer bending sections and then therefore a wider turning radius. The short tight bending section and the very tight turning radius of the upper endoscope and the enteroscope are an additional advantage in addition to their narrow caliber. So sometimes when the ultra thin won't go through, you've gotta switch to one of the scopes on the right to get through sharp angulation. One tool that we use in previous incomplete colons, regardless of whether the difficult anatomy is a redundant colon or an angulated sigmoid is water filling rather than gas insufflation. So in the redundant colon across the top in the upper left, if you fill it with gas, it becomes elongated and dilated. So each turn you go around, you use more of the scope, get over to the right colon, you don't have enough scope left to get into the cecum. On the other hand, if you don't put gas in, take the gas out, fill it with water, it stays shorter and narrower. You get around to the right colon, you've got enough scope to get down to the cecum. Prior to about 15 years ago, when I started consistently using water for redundant colons, 37% of the time, we needed an overtube, an enteroscope, something special to get to the cecum. Since the advent of consistent use of water filling, that's dropped to 7%. In the angulated sigmoid, we also use water. If you pump gas into the angulated sigmoid, because the sigmoid is mobile, it'll move up into the mid abdomen. This happens with every sigmoid. The angles, there's an average of five flexures within the sigmoid colon. They actually become more acute. You fill it with water, the sigmoid lies down flatter in the left lateral decubitus position. And the other thing is that you prevent barotrauma. Barotrauma really only occurs in patients who have narrowed, angulated sigmoids. And what happens is that in that colon, as you're passing through the sigmoid, the gas can't escape back around the scope and get out through the anus. And if the ileocecal valve is competent, you get a closed system distension of the right colon barotrauma. You can get perforation. These perforations do very poorly. They often get early onset of sepsis. They can get an abdominal compartment syndrome. You need to be ready to needle decompress the peritoneal cavity if it ever occurs. And it can occur with the use of either air or CO2. I've only had one in my career, was a fellow insertion using CO2. And so CO2 is a gas, it'll acutely distend the colon also. So water has two advantages here, making the sigmoid straighter and preventing barotrauma. The next thing you need for the very angulated sigmoid is to be able to optimize control of steering of the tip. You have to be able to negotiate that tip through difficult turns. And at the same time, keep forward pressure on the scope, the bending section into the angulated turn so that you can move through it, move around it. And there are a variety of ways to do this, but what I like to do is the so-called left-hand scope grip, where you take the insertion tube and put it between the fourth and fifth fingers of your left hand. And then you can use both hands to optimize steering because you can manipulate the up-down of the right-left controls at the same time. And you can use your hands, your forearms, moving forward or backward to control the in-out movement of the scope. You can put torque on the insertion tube and then maintain that torque in the left-hand scope grip. It requires a little bit of hand strength that can be helpful if you want the next turn to be in a particular direction. Usually the up direction is most helpful. Occasionally in a very redundant colon, you'll need an overtube to be successful. In our experience, we currently, with water filling, excellent technique, loop reduction, we need an overtube in 7% of the referred colons that are redundant. Now, of course, you would never use a device like this in an angulated, narrowed sigmoid. The black device that you see there is a reusable device from Olympus that's no longer commercially available. I've been using that for most of my career when I needed one. More recently, I've used the white overtube. This is the Pathfinder from Neptune Medical. And on the left is the device that changes it from the flexible mode to the stiff mode. I have no commercial association with this company whatsoever, but I have found this to be a very good overtube. I've used it several times, putting it in the long version. There are two lengths of it, putting it in over the adult colonoscope. And then if I couldn't get to the seek, I'm using it as a platform to put a push enteroscope through. And the few times that I've done that, it was uniformly successful. So I think it's an excellent overtube. When you're finished, be sure to write down the techniques, the tools, the scope that you use to achieve sequel intubation, because the next time the same causes of difficult colonoscopy are gonna be there, and you wanna go straight to the techniques and scope that were successful. Of course, in the very difficult colon, it's not just a matter of classifying the anatomic problem, choosing the right scope, going in underwater, optimizing steering technique. It's also essential to use basic good colonoscopy technique, which means get the loops out, abdominal pressure and position change can be important. And we're gonna discuss some of those additional elements in next week's video tip. Thanks and see you next week on the ASGE SuTab tip of the week.

difficult colonoscopies

anatomically challenging colons

high success rate

balloon endoscopes

sensitivity of alternative tests