We will, in the meantime, start with our next talk, which is going to be given by Amit Rastogi, a professor of medicine at Kansas University. He's going to be talking to us about tips and techniques and how to navigate a difficult colon. Amit, over to you. Thank you, Asma. All right. So the next topic that we'll discuss is tips and tricks to negotiate the difficult or defined colon. These are my disclosures. So the aim of good colonoscopic insertion is getting to the C-curve efficiently using good technique with the least amount of scope insertion, which is basically having the straightest possible scope, least amount of colonic distension with gas, which is CO2 nowadays that we use routinely, and also avoiding complications, which is basically by not pushing against fixed resistance and also avoiding loops and reducing loops when they form. And one of the most important things as we do more and more difficult colonoscopies is the willingness to quit. I mean, there is no harm in quitting when, in spite of your best efforts, you are unable to reach the C-curve. So let's review some of the anatomical considerations for the colon. The colon has a couple of mobile areas, which is the sigmoid and the transverse colon. Certain areas of the colon can be stretched and elongated, which is the sigmoid, the transverse, and the flexures. You can encounter sharp turns and twists in the colon, which is mainly in the rectosigmoid region, the sigmoid, as well as the flexures. And how the colon behaves during colonoscopy is also impacted by a lot of other factors like the body habitus, the intra-abdominal fat, scarring from prior surgeries, history of diabeticculosis and diabetic litis, presence of ventral or inguinal hernias, history of radiation therapy, and presence of SIDs. So if you look at the difficult or the defined colon, there are basically two main problems that we encounter. One is sharp fixed turn or a sharp angulation, or a redundant colon, which results in a lot of looping. So there are certain things that we should always consider and do during colonoscopy, which is to take a good history, which would include history of previous abdominal surgeries, history of radiation therapy, history of previous episodes of diabetic litis, what has been the previous experience of the patient with colonoscopy. We should also examine the abdomen, at least put your hand on the abdomen when you do the consent to examine for laxity of the abdominal wall musculature, look for any evidence of ventral hernia, surgical scars, or inguinal hernia. If available, always try to review the previous colonoscopy report, because that might give you some information as to what is to be expected. And one of the most important things which I always emphasize to our fellows is, describe the difficulty you encounter in your report, as well as the measures you took to successfully reach the CECA, whether it was pressure, turning the patient over, using a different score, what have you. And this is very important for future reference, because if you have difficulty negotiating the colon, the same difficulty will probably happen in a future colonoscopy. So let's talk about both these issues separately. So what about the sharp fixed angulation? This is more commonly seen in women with history of low abdominal or pelvic surgery, elderly patients with stenosing diverticular disease. As I said, always try to review the previous colonoscopy report if it is available to see if the endoscopist had any difficulty or mentioned that there was a sharp turn or not. If you know, based on previous information, that there is a sharp or fixed angulation in the sigmoid, then you may start the procedure from the get-go with a pediatric colonoscope. And if that is not successful, then even move on to a gastroscope. I usually start with an adult colonoscope, because the adult colonoscope is more stiff and loops less. But the only situation where I go with a PCF from the get-go would be prior knowledge of a fixed sharp angulation in the sigmoid. You should always hold, and this is for any procedure, you should always hold the scope with your fingers rather than with your hand. And this is because the fingers are more sensitive, and they appreciate the tactile perception against a resistance much better than when you're holding it like with the fist or clenching on the shaft of the scope. One of the most important things that you can do for sharp fixed angulation is not to insufflate gas, but on the contrary, insufflate fluid. And this is just a schematic showing that when you insufflate gas, it distends the sigmoid colon, lengthens it, makes the angle here more acute compared to when you fill the sigmoid with water, which makes it heavy, makes it straighter, makes this turn less acute. And the other, and all these will help you to negotiate to the turn. And the other important thing which we sometimes forget is continuous gas insufflation with a sharp turn or a sharp fixed angulation will result or can result in barotrauma because you're filling the colon with gas, you're struggling, it's a long procedure, all the CO2 travels upstream to the cecum, and if you have a competent IC valve, it comes to a dead end. And this is the area where you can see barotrauma, which will be in the form of linear mucosa tears and lacerations. So that is something to keep in mind. I always teach the fellows when they're doing procedures with me that torquing the scope at angulation is more important, turning the dials and torquing is more important than just pushing, because as you can see in this diagram, when you push at an angle, you basically make the angle more acute and more difficult to negotiate. So torque the scope rather than pushing, turn the dial, up-down dial with your left thumb. Keep the scope short and straight. And if after your maximum torque and moving the up-down dial, you are unable to negotiate the turn, then it's the time to use the left-hand grip so that you can free the right hand and use the right hand to move the dials, the short dial or the small dial for right-left deviation. So you take your right hand off the scope, you hold the scope sharp with your little finger of the left hand, and then you use your right hand to move the small dial to get further turn to negotiate a sharp angulation. Now if all that is not making you negotiate the turn is not successful, then you can apply pressure and the direction of the position of the pressure should be in the right lower quadrant directed middly and downwards. And if that is also not helping, then it's about it's time to change the scope, either go to a PCF first, a pediatric colonoscope, and if that does not help, then you can even go in with an upper endoscope. And here you can see that the bending section of the PCF and the gastroscope compared to the colonoscope is much shorter, and the entire curve or this area that you have of the bending section is much smaller for the pediatric colonoscope and the gastroscope compared to the adult colonoscope. If that is also not helping, then it's time to change the position of the patient to supine and apply right lower quadrant pressure, and if that also does not help, then change the position to right lateral position. I usually do the change of the scope or I change the scope before I change the position of the patient just because with more and more procedures being done under MAC or under propofol, it's just cumbersome to change the position of the patients. You need a lot of help, but if it comes to that point, then you will have to do that. I just wanted to show you that never underestimate the value of changing the scope to a smaller diameter scope because this is what happens if you have the adult scope as the reference, the diameter of the pediatric colonoscope is about 10% less. But if you look at the circumference, the reduction in the circumference is 20% because the circumference is 2 pi R. And similarly for the gastroscope, the gastroscope diameter is 25% less than the colonoscope diameter, and the surface area is almost close to 45% lower than the colonoscope diameter. And the other thing to remember is that when you have a sharp fixed angulation in the sigmoid and you negotiate it with a gastroscope, usually after that, it's a straight shot to the cecum. So even with the limited length of the gastroscope, majority of the times you'll read the cecum because that fixed angulation is tethering and fixing the colon and avoiding any loops. And that will be enough for you to get to the cecum even with the limited length of the gastroscope. These are just the degrees of deflection of these scopes. And this is important to remember also because sometimes we have older scopes, the cables are loose, and the deflection of the scope is not what it should be. And that can be a limitation or a limiting factor when you are trying to negotiate a sharp fixed turn. So something to keep in mind is to pull the scope out and check the deflection. And for that, you should know the ballpark degrees of deflection up, down, right, left of different kinds of scopes. So another thing that has been shown to be beneficial is starting the procedure in the right lateral position instead of the left lateral position. One study showed that in women and in patients with history of abdominal surgery, you got to the cecum faster when the starting position was right lateral. But overall, meta-analysis have not shown a significant difference in the cecal intubation rates and time between these two positions. But something to keep in mind in difficult cases where you have been unsuccessful in reaching the cecum or negotiating the sharp turn in the left lateral position after using all the other remedial methods that we discussed before. Now the second type of difficult or defined colon will be a redundant colon in which there is excessive looping. We should anticipate that in patients who are obese, have a lax abdominal wall musculature, have a large ventral hernia, inguinal hernia, or history of chronic constipation. How do we identify a loop? You should assess your location in the colon and the length of the scope inserted. And if there is a disconnect between the two or discordance between the two, you know that you have a loop. What are the signs of looping when you are inserting the scope? You will see a loss of one-to-one, one-is-to-one insertion and forward movement, which means that you're pushing in the scope 10 centimeters, but the tip of the scope is moving ahead only a couple of centimeters. You will feel resistance to the insertion. You will have too much of scope in the patient in relation to the location. For example, you might be reaching the sphenic flexure and you have about 90 centimeters of the scope already in. That should warn you that there is already a big loop in the sigmoid colon. And also the patient will have abdominal discomfort. That should also alert you to the fact that there is a loop that is causing this pain to the patient. Always try to reduce the loop. I think loop reduction is the key to good insertion technique. After you reduce the loop, if you have the scope, a type of scope that has variable stiffness, you can stiffen the scope, and this can help also to prevent further loop formation. Let's spend a few minutes discussing the different types of loops and where they form and how do we take care of them. Sigmoid loops are the most common. There are different kinds. You have the alpha loop, which is shaped like an alpha. The scope goes in, turns around anteriorly, and then goes towards the descending colon. You have the reverse alpha loop, which goes posteriorly, and then you have the end loop, which is the most common. One of the things that also should alert you that you're forming a loop is if you have very easy insertion and the colon looks featureless with flattening of the hostile folds without any angulation, basically this means that you're just lengthening and stretching the colon, you're not advancing too much forward, you're just elongating the colon and forming a loop. Now, once you form a loop and you identify it, you should talk right to withdraw the colonoscope. This is usually very effective for the alpha loop. How do we know that you've reduced the loop? What will happen is the tip of the scope will stay stationary on your screen, whereas the insertion tube will come out of the patient. In that way, you know that you've reduced the loop. If the clockwise torque doesn't work, then you should try counterclockwise torque, which is always helpful for the reverse alpha loop. The aim is to keep the insertion tube straight as you negotiate the sigmoid and reach the splenic flexure at around 40 to 50 centimeters, and this will make the rest of the procedure much easier. Now, if after reduction, the loop forms again on advancing the scope, now you need to give abdominal pressure and always have a very low threshold of getting pressure. I always tell the fellows there are no negative points for getting abdominal pressure. The negative points are putting in loops and struggling and getting to the C-term with almost all of your scope in the patient. So you should get pressure, and the first area is the right hypogastric region and direct the pressure medially and downwards, and that is also very important that when you have your tech giving pressure, just don't tell them to give pressure. Give them the exact location where you want the pressure as well as the direction which they should be pressing. If the right lower quadrant pressure is not helpful, then you can try left lower quadrant pressure. And the other thing that helps a lot to avoid loops or help in preventing loop formation would be water immersion, which will also keep the sigmoid heavy and straight and decrease the risk of it looping. Now once we negotiate the sigmoid, usually the descending is not too difficult to negotiate. We get up to the splenic flexure where we can encounter some problems, especially if it's high and floppy. It can get elongated and acutely angulated. How do we identify that we are in the region of the splenic flexure? You have a straight scope in the sigmoid, and you're having difficulty entering the transverse colon, you should see a sharp turn, which you're not able to negotiate easily. That should alert you that this is a difficult splenic flexure. How do we negotiate this? Again, as I said, torque, turn your dials towards the lumen or towards the turn. Sometimes suction of the air will help because when you suck air, that propels the tip of the scope forward a little bit, but just by the action-reaction mechanism. And avoid pushing too much because if you push too much, you'll just make the angulation of the splenic flexure even more acute and also increase the loop. What can help also here is left upper quadrant pressure. Again, you have to instruct your tech where exactly you want the pressure, just below the ribs on the left side of the patient and directed inferiorly. If all this doesn't help, then you turn the patient to the supine position. And then if that is also not helping, you can turn them into the right lateral position, but usually supine position and pressure on the left upper quadrant will be good enough. And sometimes you have to give pressure in two locations. So you have to have a forehand pressure for the sigmoid as well as for the splenic flexure to negotiate the turn and get into the transverse colon. Always be cognizant of the risk of splenic injury when you're negotiating a difficult splenic flexure. This is just a quick example of how the loops look like on ScopeGuide, which is magnetic endoscopic imaging. It gives a 3D view of your scope, how the scope configuration is in the colon. Here we're going through the sigmoid. As you can see, I'm pushing and we're forming a loop in the sigmoid, similar to the alpha and the reverse alpha loops that we talked about. And before it can form any further, I just talk and reduce and you'll see the loop reduces here and the scope just jumps forward. Then it'll be relatively easy to push this up. If need be, you can get pressure on this side, which is the right hypogastric region. Now we reach the splenic flexure and we are having difficulty negotiating the turn. You're struggling a little bit and you'll see in a little bit on how I will elongate the splenic flexure coming anteriorly and then making the turn into the transverse colon. But this is something that has to be remediated. So we'll again, pull the loop out. And as you see, as you straighten the scope, it flies down the transverse and you negotiate the hepatic flexure. Now you have a straight scope accessing the, going towards the C-cup. So this is the configuration that you want when you're intubating the colon, a straight scope without any loops, about 80 or 90 centimeters of the scope in the patient. So once you get into the transverse colon, this is also a mobile portion of the colon due to the large meso colon. The loop, transverse colon loop will descend downwards and you will lose one-to-one progress. That's how you recognize this. You apply abdominal pressure. The location of the pressure is in the mid abdomen and directed upwards. And again, if you're not successful and you have a big ventral hernia and the patient is very obese, then you need two people to give pressure with four hands. And you just have to get the pressure at the appropriate locations. And that will help you to advance the scope. Sometimes folks recommend massaging the abdomen, which helps to propel the tip of the scope forward. That can be also tried. And if all that doesn't help, then you can turn the patient to the supine position. That will help you to give, or help the tech to give good pressure onto the transverse superiorly. Now, after the transverse, we get to the hepatic flexure, usually to negotiate a tight hepatic flexure, counterclockwise torque, with a little bit of suction of the air is good enough. If a loop is present downstream, then you can hook, once you negotiate the flexure, you can hook the tip of the scope at the flexure and gently pull out to straighten the scope and reduce the loop. And by this mechanism, you will see that the tip of the scope just advances forward. So this is the paradoxical motion that I talk about with the fellows, is when you're reducing, the tip of the scope goes forward in the ascending colon. Sometimes you might have to rotate the patient to the supine position, and not even that, you can just rotate the shoulders towards the bed, the right shoulder towards the bed, like a half rotation. And that will help to open up a sharply angulated hepatic flexure and helps you to get past it and reach the ascending colon. Once you pass the hepatic flexure, and if you lose one-to-one progress, then what you can do is put a counterclockwise torque and exert gentle rocking movement back and forth of the scope and suck the air. And with that subtle movement, you will see that the tip of the scope will advance forward towards the cecum. Sometimes if you can see the cecum and you can't get there, you can ask your tech to apply pressure over the cecum, direct it superiorly, or also right flank pressure. So these are the two different areas of pressure that will help you to get to the cecum. You might need four hands. And if this doesn't work, then the other option would be basically turn the patient to the right lateral position, which is obviously a little difficult to do in patients who are in a proper false sedation. But if the cecum is visible and you've tried everything, forehand pressure, torquing, stiffen the scope, and you can't get there, then just turning the patient to the right lateral position and you will just automatically dip into or sink into the cecum and get there very quickly. So things to remember. Sometimes pressure doesn't help. You have to be aware of this fact that if you're applying pressure, you have straight scope and it's not helping, then take the pressure off because sometimes pressure can also impede the progress of the scope. You have to give specific directions to your tech regarding the location and the direction of the pressure. Sometimes you may need two techs to help out. For difficult colas, you might have to have four or six hands on the abdomen of the patient, pressing on the sigmoid, the transverse, the splenic flexure to get to the cecum. Always be aware of ventral hernias and inguinal hernias as these can be troublemakers. Be aware of the risk of aspiration, especially if you turn the patient to supine and right lateral position and you're applying abdominal pressure because they've taken the prep, they still have the prep, they have gastric secretions. If the patient starts having hiccups or starts coughing, then you should be aware that, or you should think about the possible risk of aspiration in this situation. And as I mentioned earlier, be ready to quit. If in spite of trying your best, you can't get to the cecum, there is no harm. You can either try on another day and during the next time you start with water immersion, load the sigmoid with water to make it heavy and let it sink down so that it loops less and has less angulation and apply abdominal pressure from the very beginning. And obviously if you can't get there, then refer the patient to one of your more experienced colleagues or a regional expert to get to the cecum or complete the colonoscopy before you try any other imaging method for screening like CT colonography or what have you. Quick word about water assisted colonoscopy. There are two techniques, water immersion, water exchange. In water immersion, you infuse a lot of water in the sigmoid whereas in water exchange, you infuse the water and remove it at the same time as you push the scope in. Studies have shown that you can improve your cecal intubation rates compared to gas insufflation. Does take a few extra minutes and especially for beginners, it might be a little challenging because you can't see the lumen or you don't see the lumen that clearly and that can be a little bit difficult for trainees when they are trying to do complete water exchange or water immersion without any gas insufflation. Studies have shown that you take some extra time to get to the cecum and but also there is less patient discomfort, especially in unsedated colonoscopies. This is just a quick video of water immersion or water exchange colonoscopy. Here, I'm just insufflating water and sucking it at the same time. So basically more like water exchange. As you can see, you have to have a good prep otherwise this will not be possible. You don't see a good lumen, but you're just anticipating which way the lumen is going by the convergence of the folds and then you're pushing your water jet in that direction to open up the folds. As you can see for beginners, it can be a little bit challenging. So I always tell my trainees to use a hybrid method where you can use water, but little puffs of CO2 insufflation to help you figure out which way the lumen is going. So here, this is kind of an unedited almost insertion phase. You're trying to make the turn. One of the difficulties is you might not know your location in the colon because you're not seeing the lumen that well, but once you get to the transverse colon like here, you can see the triangular shape and you know you're getting closer to the hepatic flexure. You keep going, try not to insufflate any gas in spite of all the temptations and keep moving forward. And as you'll see that we'll be getting into the ascending colon now, made that turn and we're going straight now. Now, if you, other issue here is recognizing the cecum. So if you have about 70 to 80 centimeters of the scope in and you're coming to a dead end and you can't find which way the lumen is going, always suspect that, okay, I've reached the cecum now. And here, as you could see, you could see through the water, the appendicial orifice, and here is the cecum. And now you can come back, insufflate air to get confirmation. And then you start suctioning all the fluid that you insufflated and basically start the withdrawal process. So this is a short demonstration of how you do a water-resistant colonoscopy. Other accessory or adjunctive things that will help are abdominal binders. This is a commercially available one, which was shown to be helpful in a randomized blinded sham control trial. Basically, the main crux was in mild to moderate obese patients, there was shorter cecal intubation time if you use the abdominal binder because it just provides more support to the abdominal wall, prevents looping. And there was a trend towards reduction in manual pressure and change in position, but something to have in your armamentarium. I don't use these commonly, but in patients who are obese and have a very lax abdominal wall or a big ventral hernia, something to think about. Then we talk about scope guide. I showed you a video. Multiple studies have shown that it lowers the risk of failed cecal intubation, lowers the cecal intubation time. And basically this is all because you can get a visual representation of how and what your scope is doing so that you can take remedial actions, whether it is reducing the loop, applying pressure, what have you. And also has been shown to reduce the pain score. So overall, something which is of utility, it does come with an extra cost. So that has been the main negative for this technology, but another way of reaching the cecum or in a difficult situation, especially when you have a loopy colon. You can use rigidizing over tube. This is one type which is commercially available, which is very flexible in its native state. It is advanced over the scope. After you reduce the loop, you advance this over the scope and then you apply the vacuum and this will stiffen the scope, stiffen the over tube 15 force. And what that stiff over tube does is avoids loop formation in the segment of the colon that is traversed by the over tube. So basically if you have a big loop in the sigmoid colon, you reduce the loop, pass this over tube, stiffen it, and then for the progression of the scope will avoid looping in the sigmoid colon. Lastly, you can try a single balloon or double balloon entroscopes just because they have over tube and they have longer length. The meta-analysis showed that success rate can be up to 97% of fecal intubation in patients who had failed colonoscopies takes about 21 minutes at a mean. When they looked at the reasons for failure, more than half of it was due to excessive looping. The other about 25% was due to fixed sigmoid and the rest was due to pain during the procedure. I would confess that I've not had good success with double balloon entroscopes and single balloon entroscope just because they are pretty floppy, but there's something to keep in mind in failed colonoscopies. Lastly, referring to an expert is very important. You should have someone in your practice or in your town or in the region where who you could refer, who has a track record of doing difficult colonoscopies. This is a study published by Doug Rex and I'm sure there's newer iterations to it because he's had many more patients now. He was able to reach the C-cum in 96% of the patients who were referred for failed colonoscopy and his main message was try water immersion versus gas insufflation. And when he did that, he was the need to use an external straightening device on the overtube was much less compared to when he was using gas insufflation. And in failed colonoscopies for redundant colon specifically, the need for external straightener was also significantly less when he used water immersion compared to gas insufflation. And even the position changing requirement was significantly less when I use water compared to gas. Overall, if you are the person doing a failed colonoscopy, water is the way to go versus gas insufflation. So in conclusion, you should anticipate the difficult or the defined colon, take a good history, examine the abdomen, review previous records, use less gas insufflation, as less gas insufflation as possible, use water aided method for sharp angulations, less pushing is the way to go, more torquing and dial turns, use the left-handed grip. If you have to move the small dial with your right hand, use water aided, change to a smaller caliber scope, apply abdominal pressure, and then lastly change the position of the patient for redundant colons, anticipate the location of the loop, type of loop, and reduce as necessary, apply abdominal pressure, again, water immersion is helpful, and then lastly change of position. The other adjuncts that you can use are overtubes, the scope guide, abdominal binders, double balloon endoscope. The most important thing that you should not do is do not push against fixed resistance, especially without a visible lumen, because that invariably may result in or can result in perforation. And document the difficulty in the report, have a detailed description in the report as to why was it difficult and what were the measures you took to remediate and get to the CECOM, because this will help you in your future colonoscopy or anyone else who does the future colonoscopy. And be prepared to quit and refer to an expert. Thank you.

colonoscopy tips

difficult colon navigation

colon anatomy considerations

problems in difficult colons

techniques for negotiating difficulties

alternative methods for difficult colonoscopies

importance of documenting difficulty