So, this is fun, okay? These are tools of the gastroenterologist. Obviously, I deal with these a lot, and I see a majority of you folks are from device companies, so this will be fun. All right, so general GI and interventional GI, and I think ASG is also trying to, you know, divide these sort of aspects in educational sort of thing as well, because as you saw, even among our faculty, there are folks, you know, who call ourselves general GI faculty, and there are folks who call ourselves the interventional or the advanced GI faculty. So we'll go through the similar way here, where we are dividing our procedures as endoscopy and colonoscopy as general GI, the EUS, ERCPs, and there are certain other procedures which come as the advanced GI. We're going to focus only on ERCP and EUS in this particular talk. So endoscopic examination of the upper GI tract, you have esophagus, stomach, and the duodenum. You know, in short, we just call it EGD. Some call it endo, some call it, you know, upper GI. They're kind of all synonymous words, depending on, you know, which part of the country you're in and which lab you're working in. But the focus is on examination of the esophagus, stomach, and the duodenum. Typically the first and second portion of the duodenum, we don't tend to go beyond that in the upper endoscopy, occasionally we do. There are several indications to do the upper endoscopy for abdominal pain, it could be for different symptoms of acid reflux, we call that heartburn, chest pain, could be any of those symptoms we are suspecting, reflux disease, it could be for difficulty swallowing solids, liquids, depending on the indication, there are several causes for that. If somebody has low iron levels, Dr. Martin mentioned that the duodenum is critical in the absorption of iron. So somebody has low iron levels, we not only do a colonoscopy to make sure they don't have any cancer, but we also do an upper endoscopy for the absorption effect, if the duodenal lining is normal, but also certain ulcers which can cause slow bleeding and resulting in low iron levels in the blood. So we do endoscopy for that. If there's any sign of bleeding, whether they are vomiting blood, or whether they have black stools, blood as it courses through the intestines gets digested, the protein part of it gets digested and looks, instead of looking red, it starts looking more black and tarry, and that is called melanoma. So if they have signs of bleeding in that aspect, if they, either you're suspecting they have varices because of certain liver conditions or certain other pathological conditions, or if they, again, are throwing up blood and you're suspecting varices, you do an endoscopy for that. Foreign body removal or food impaction. The foreign bodies sometimes are intentionally ingested in folks who have certain psychiatric problems, or sometimes it could be accidentally ingested. So for both such indications, you do the endoscopy. Food impactions can happen in sad situations where, you know, elderly folks, they're not chewing very well, you know, they swallow a bigger piece of meat and just get stuck, or it could be certain other conditions where the esophagus is really narrow and you're not able to, you know, pass through certain food and the food can get stuck. Or for placement of additional, for nutrition purposes, a placement of a feeding tube. The endoscope insertion from the endoscopy, from the EGD standpoint, is always done under direct visualization. So we don't tend to go just blindly passing the scope. You have a lens, you have a camera, we look for certain landmarks. So this is a great picture we teach our fellows in terms of identifying these landmarks and knowing where to go. So this is kind of the front of your body, and this is the back of your body, okay? The cameras in the endoscopy, and when we go to the sim lab, you'll see, it actually inverts the image so we have a little more, you know, more natural, normal feel for us when we're doing the endoscopy. When you actually put it on the keyboard here, the F3 will look, you know, upside down because of how the cameras are oriented. But so these landmarks, right, so these landmarks here, so these are vocal cords going into the lungs, so that's the trachea behind that. And the epiglottis is over here that sort of, you know, flaps around your airway. These are areopiglottic folds. This is your pyroform sinus, and your entry into the esophagus is right behind here. So either you go into this and kind of turn right, or you go into this and turn left, and you enter behind this into the esophagus. That's the inlet into the esophagus, and that's how our food naturally finds its path. And you'll be like, you know, how does a food find its path, right? It just naturally finds its path, and that's a coordination of your pharyngeal muscles, muscles in your pharynx and your throat, allowing food to pass down into the esophagus. So you heard about this already. It's a GE junction, and some folks, we call it now the EGJ, whatever it is. It's a junction between your esophagus and the stomach. Depending on individual, it could be anywhere somewhere 35 to 45 centimeters from the incisors, your teeth. As Dr. Guha mentioned, the Z line, which is naturally very irregular, and it represents the connection between the esophagus and the stomach. The esophagus looks much more pale pink. The stomach looks a little more kind of salmon-y colored, or we call it orange or salmon-colored. The top of the gastric folds marks the beginning of the stomach, and this is the top of the gastric folds, which are kind of, you know, more folds like this. The esophagus looks more flat, while the stomach has folds. And this is the endoscopic view of the GE junction, where you see the endoscope is kind of, you know, shining light. This is the angle that you're seeing, the angle of hiss that Dr. Guha mentioned, esophagus and the stomach line. As you enter into the stomach, so it's almost like a virtual show here of different pictures of how the stomach looks as the endoscope is passing through. In the upper part of the stomach, this is the lesser curve of the stomach, and this is the greater curve of the stomach. And as you go down into the lower part of the body of the stomach, the same kind of relationships, you know, on the top, you have the lesser curve, and on the bottom, you have the greater curve, lesser curve and greater curve. This part of the stomach is the antrum, very close to the pylorus, that's the opening going into the duodenum. And as you enter the duodenum, the first part of the duodenum, which is the duodenal bulb, it's a little more capacious, a little more, you know, wider. And then you start going down that sweep of the duodenum into this area here. And you get into the second portion of the duodenum, where sometimes you don't always see the major papilla with the forward-viewing endoscope, which is what the EGD scope is. The ampulla is more on the sideways sometimes, and that's why you require a special scope to be able to visualize the ampulla and perform the ERCPs, those are side-viewing scopes. And when we come back, we do retroflexion in the stomach, which is looking back on the scope itself, making the scope into a J or a hockey stick sort of a configuration using the wheels. And so this sort of shows you the G junction in retroflex view. And this part of the stomach is called the fundus of the stomach, which is what you're trying to visualize by retroflexion, which you cannot see in forward view completely. So switching gears into the large intestine, the different parts of the colon were already kind of explained to you, anus, rectum, sigmoid, descending, transverse, ascending, and cecum. And this is the opening of the appendix in the cecum, which usually marks the end of our extent of advancement with the colonoscope. You can also evaluate terminal ileum. Terminal ileum is the opening of the small intestine into the colon. If you're doing a colonoscopy, in majority of the cases, you do require a clean colon. In some cases, when the patients are obstructed, you cannot give them a preparation. You do the colonoscopy without a prep. It's not fun. And you give them laxatives. There are several brands of laxatives available that we give them to clean out the colon. The major reason why we do colonoscopies are for screening for colorectal cancer. That kind of accounts for probably a chunk of the colonoscopies. Screening is done for folks who are asymptomatic, or if they have family history, or they have other cancers, or other genetic conditions, which puts them at a higher risk of having colon cancer, while surveillance is once you identify a polyp, or you've had a patient who had a cancer before, and that becomes a surveillance. You're putting them on a follow-up plan for that. This is a great picture that we share with our fellows as well in teaching, so that there is different stages through which colon lining goes before it becomes cancer. It starts off as a little bit of increased growth, then it becomes a precancerous type of growth, resulting in a bigger size, and bigger size, and not necessarily always a bigger size, but sometimes the changes could happen a little bit faster than you expect because of either genetic condition, or certain other pathways that the proliferation goes through. It becomes cancer that is initially confined to the superficial lining of the colon, and then it starts eroding into the submucosa, which is a second layer of the colon that becomes an invasive cancer, and then as you leave it alone without doing any intervention, it starts becoming deeper and deeper. You want to catch this before it turns into even this. You try to catch it either in this stage or in this stage, then you are really saving the patient from developing a cancer. Unfortunately, majority of my practice, I deal with more of these, because now we have polyps that have grown to the size, or have changed to form cancers within the first lining, and then you have to remove them. You can still remove these endoscopically and save them from surgery, and some select groups of these polyps also, you can remove them endoscopically and save from having a surgery. Several indications for it, similar to the upper endoscopy, if they have pain that is more in the region of the lower abdomen, or other associated symptoms that point towards the colon. If they have blood in their stool, if they have low iron levels, again, we talked about polyps and cancers causing iron deficiency, anemia. Inflammatory bowel disease, Dr. Abraham's specialty, diarrhea. Sometimes you do biopsies to make sure there's no inflammation in the colon. And also, if there is any abnormal scans, so they got a scan for something else and they found a growth, or found something abnormal in the colon, you have to directly visualize it or take a biopsy and make sure everything is okay. The therapeutic indication, removal of polyps ends up being the majority of the times. If you have bleeding, if you want to localize where the bleeding is coming from, valvulose is one of those indications where you cannot prep these patients. These are twisted, large intestines resulting in bowel obstruction, and you do a colonoscopy and straighten out the colon, essentially, and help decompress the colon. Occasionally, the colon is also blocked off because of a cancer. In those cases, again, you cannot prep these patients. You just give them enemas as much as you can, and you go to find the area of the obstruction and place a stent. So, these are all some therapeutic indications of why you do a colonoscopy. All right. So, the accessories and tools. So, there are several tools, and it's ever-expanding, this area. More and more devices seem to be coming on the market for us to use. But the basic ones are biopsy forceps. You have snares. You have baskets and nets, injection needles, clips, different electrocautery probes, some band ligators, and we'll go over a few of these in terms of what their purposes are. So, forceps, as you would think of, they are used to take tissue, either in the form of tissue. Some forceps are also used for coagulation as well, but the majority of the forceps are used for obtaining tissue. They're from various sizes. You can have them with the center spike, which allows tissue to not get lost, so you can take more than one bite with it, and the ones without the spike, where typically you tend to do only one bite with those. Snares, the main purpose of snare is to remove polyps, and they, again, come in various shapes and sizes. It's a good picture showing the different types of snares. There are certain special features of these snares as well, and not only the shape, but also what sort of, are they monofilament, are they made of single filament, are they made of two different wires, are they braided, are they thick, are they thin? There are several aspects of the snares, and you ask each one of us, we'll have our own special snare that we love to use for different polypectomies. There are some snares that have an injection needle with it as well, so there's all kind of innovative things for these snares that you guys come up with in different companies, sometimes with our ideas and sometimes with your own ideas. So the technique for polypectomy with a snare, so there are different types of polyps. This one is kind of showing a polyp that is on a stalk. It almost looks like a broccoli head, right? So this is a little head on a stalk, and it's kind of easy to visualize or kind of understand how snares work. You put this snare around the polyp. Sometimes the limiting factor could be the size of the snare and the size of the head of this polyp, so to select the right snare to kind of fit through and get underneath closer to the base and be able to choke the blood flow off the polyp. And then you have a choice to either use cautery, which is called the hot snare, or not use cautery, which would be the cold snare. I would say in majority of the cases where you're seeing a stalk like this, you probably end up using cautery and using a hot snare because they tend to have a good blood vessel within the stalk that will bleed otherwise if you don't use cautery. And then there are other types of polyps that are more flatter polyps, and in those cases there's no stalk, but the concept is similar. You're still putting a snare around it, trying to capture all of the polyp, and try to cut the polyp, almost create like a pseudopolyp like this by tenting it, and then being able to resect the polyp, again, using either heat or no heat. So this is a small video clip kind of showing how the snare is placed over the polyp. Look at that, and then it's closing the snare, making sure you have normal tissue, and he's applying heat here to get the polyp resected, and now it is kind of separated from the colon wall. Another hot snare polypectomy, the endoscopist here is putting a snare. So this is a little more flatter polyp than the previous one, but again, you're creating that almost like a pseudostalk by using the snare around, capturing the base, and you're lifting, tenting away from the colon wall so that the heat doesn't get conducted through the colon wall and create a perforation. So you're lifting it up, applying heat, and cutting off the polyp, and that's how the polypectomy base will look like when you applied heat. All right, and once you have removed the polyp, sometimes we just use the suction. If it's a small enough piece to kind of, you know, pull the polyp through the channel of the endoscope, occasionally if there are big polyps, you may have to use devices like these called baskets or nets, and you also use these for foreign bodies as well to remove. Again, they come in different shapes, different sizes. You know, some of them have extra, you know, wiring on it to maintain the integrity of the basket. Again, this is all innovation site where, you know, it gets really interesting. So this is polyp retrieval. Here I think we're using a net to retrieve it, and this is suctioning the remaining smaller pieces, and here you're just using a snare to capture the polyp and then either you could remove it like that or sometimes you can cut the polyp into smaller pieces if you're not worried about an advanced pathology. And this is again using a net to capture it and remove it. Injection needles, the purpose of injection is if you're trying to deliver a medication into a certain area like epinephrine sometimes if you're trying to stop bleeding. You can also inject steroids like Kenalog for when you're dilating a stricture to increase the interval between dilation. Steroids tend to delay the scar tissue formation. Or you can inject a spot dye for marking for a future polyp resection or sending the patient for surgery. Or for removing large polyps, we try to protect the muscle layer of the colon wall by injecting fluid underneath the polyp in the submucosal layer and do our endoscopic mucosal resections or endoscopic submucosal dissections to take out large polyps. They come in different gauges, different sizes. So the size of the needle is measured as a gauge. And typically from the catheter when you ask your technician to open the needle, it jets out from the catheter a few millimeters. And depending on the type of the catheter, it could be different lengths. So the major reason, as I said, is to inject certain medications for hemostasis, for lift polypectomy, the EMR-ESD POEM procedures for achalasia. That's another area where we do inject fluid to do therapeutic procedures. The tattoo, that is the marking, tissue marking. Botox is another indication where you're trying to relax certain muscles like in achalasia, the muscle that Dr. Guha was talking about, the lower esophageal sphincter is a little too tight and not allowing food to go down, not relaxing when it's supposed to be relaxing. Botox temporarily at least relaxes that muscle, allowing food to go down. The effect typically lasts for about three to four months before patients start having a relapse. Similar thing with gastroparesis, when there is delayed emptying of the stomach, one of the mechanisms you can allow the food to empty out of the stomach is by relaxing the pylorus muscle, the opening between the stomach and the duodenum. By injecting medication there, you can also allow food to pass through. So this is a video sort of showing you the submucosal injection to do an EMR. So here the fluid is getting injected into the submucosal layer, and you know that it's in the submucosa because of the lift that you're seeing. If it is in the muscle, you won't see that lifting. And there are several agents available in terms of doing the lift. And most of us, when we are doing the lift, we also put some dye into the fluid to allow easy differentiation of the polyp from the surrounding, like in this case, you can see the bluish hue now. To separate the polyp from the surrounding, you can actually clearly see where the margin of the polyp is. But also once you do the resection, the muscle does not take up that stain. So you can separate, you can see the muscle, and you can also know if there is any injury to the muscle layer or not. So that blue color becomes really important for EMR and ESD, as well as for POEM procedures. Clips, again, there are several types of clips, lengths, sizes, and there just seems to be more and more innovation in this particular area. There are clips that have a central bar, allowing you to grab one end, the other end, and then be able to close together, even in larger defects. Shorter stem clips, wider wingspan of the clips, I mean, you can name it, there's several tools here. The major purpose is for bleeding and for closing mucosal defects after EMR or for ESD sometimes. Electrocautery probes, this is one of those catheters. This is a gold probe, it's a gold-plated electrocautery probe that conducts energy. There are also forceps that can do the same function, conducting heat and being able to stop a bleeding vessel. And the overall principle is the same, which is they generate heat by passage of electric current through the probe, and they're cauterizing tissue, slowly kind of cooking the tissue and coagulating, whether it's a blood vessel or a bleeding tissue. APC, on the other hand, is a different modality of hemostasis. You're also stopping bleeding in majority of the cases with APC. Occasionally, you also use APC for tissue destruction as well. But in terms of the hemostasis, the difference between this and the cautery probes is this one is a non-contact cautery. That means you're actually delivering energy through ionized argon gas. You're not touching the tissue, you're staying a few millimeters away from the tissue, stepping on the foot pedal that allows the ionized gas to go through the catheter, and it delivers energy through the gas onto the tissue. So it's very superficial compared to, go ahead. It's very superficial, so I was just gonna say that. It's very superficial energy, but if you step on it for long enough, you can go deeper, but it doesn't go as deep as the contact methods do. So for example, if you saw like a big bleeding blood vessel, in those cases, you don't tend to use the APC as your modality, but you use the cautery probes as your modality of choice. But you could also use APC for tissue destruction as well. Similar concept, you're burning the tissue and you're essentially ablating the tissue. Sometimes when you're doing either removal of polyps, et cetera, there is some residual part that just cannot remove. In those cases, you can use it. Also, after doing an EMR, the current standard of practice is to treat the edges of the EMR with some coagulation. So typically we use our snare itself, the tip of the snare, to do that coagulation, but some of us also use APC to kind of give a little better predictable depth as well as width of that ablation. And that reduces the polyp chances of coming back at a later point. Even studies have shown from 20%, it goes down to about 2% by doing that treatment. So the technique, as I said, is electric current passed through a jet of ionized argon gas. It coagulates bleeding lesions without any physical contact. Band ligation, you're using it for banding of esophageal varices as well as for mucosal resection. The technique is you're trying to create a pseudopolyp by a flat polyp or a flat lesion, you're changing that into a pseudopolyp when it comes to the mucosal resection part of it. You're sucking that tissue, deploying a band under the base of that tissue that you have sucked in, and if you're removing it, removing tissue, you put a snare underneath that band or above the band, depending on your comfort level there and how much tissue you have grasped, and resect the pseudopolyp that you have made by this band. So that's for the mucosal resection. For varices, the varices tend to be very juicy, plump vessels under the mucosa, and you use this to kind of suck that blood vessel in and you leave a band, and over time, the blood flow just kind of fades away and the blood vessel there kind of sloughs off, and that's how the varices get obliterated. So you do them periodically over time, and eventually the varices get obliterated with the banding. So this is sort of a picture exemplifying that suctioning, getting enough tissue, and then putting a band underneath that varice. ERCP is used for endoscopic examination of the bile duct and the pancreas. We're using x-rays for this. There is a difference in terms of how the ERCP scope, which is a side-viewing scope compared to the forward-viewing scope, there are several indications for it for removal of stones, for dilating strictures, placing a stent, even doing biopsies inside the duct, and the side-viewing aspect of the scope allows the devices and catheters not only to come at an angle that is helpful to go into the major papilla, but they can also use the elevator to deflect the catheter up or down, which is an important function to be able to drive catheters up into the bile duct or the pancreatic duct and be able to manipulate it that way, which is very different compared to the forward-viewing endoscope, where the channel, instrument channel is here, the instrument channel is all on the side. So in the ERCP scope, go ahead, yes. I'm not familiar with ERCP, so this is a naive question, I apologize. How are you? No naive questions here. This is called the basic ARIA course. Good, well, this is a basic question. So with ERCP, how are you getting the scope down? Are you using a forward-facing scope and then doing a guide wire transfer or something like that? If it's side-viewing, I'm just curious, how do you know where you're going? Right, so it's a very good question. I was just about to say that, actually. So compared to the forward-viewing scope, the side-viewing scope does require a little bit more practice, because it is blind, a little bit of blind, especially when you are passing through the esophagus. In the esophageal inlet area, remember the picture that I showed you with the forward-viewing scope, you clearly see all those landmarks. You don't necessarily see that type of landmarks with the side-viewing scope, but you can see certain other landmarks. For example, as you're passing the tongue, you see the separation of the tongue and the palate, and then as you go down, you do see the epiglottis and you do see the adiapiglottic folds, and then you know you just have to be behind it. It's almost like you're driving. You can see some things, right, but you're driving knowing that that's not where you're going. You're going below the area that you're seeing. So it just requires a little bit of mental training to be able to pass the side-viewing scope. So it does require additional training to be able to pass the side-viewing scope. Thank you. So ERCP is, you know, examining the bile ducts, the anatomy that we went over in the previous lecture, which seemed like an hour ago, and this is the cholangiogram that you can demonstrate by doing an ERCP. So you're injecting contrast into the bile ducts, and that's sort of, you know, showing you the left-right hepatic duct, cystic duct going, and I don't think this patient has a gallbladder. I'm not sure. The gallbladder is not opacified here, and the bile duct and coming down into the intestines of the ampulla, they actually also pacified the pancreatic duct, which we try not to do if your focus is only on the bile duct, but here you can actually see the pancreatic duct as well going into the major pepulae, and that's how we investigate both bile and pancreatic ducts. Kind of similar thing with the pancreatogram on this particular case. This is the pancreatogram with the pancreatic duct, sort of much smaller compared to the bile duct usually. The endoscopic ultrasound, you're combining ultrasound with endoscopy. Dr. Guha explained to you the five layers, and we are seeing the five layers here. Superficial mucosa and deep mucosa. It's just right here underneath. Submucosa, muscle layer, and then it's the outer adventitia or cirrhosa. You can use it to examine the upper GI tract or bile ducts and pancreas as well as rectum. Sorry, we went back here. All right, so there are several indications for it. You can use it for staging of cancer. You can also use it to do biopsies for evaluation of submucosal lesions, for gallstone disease, as well as for drainage of pancreatic pseudocysts. The EUS now is also used for other therapeutic interventions like doing gastrointestinal bypasses or bypass between the colon and the small intestines and so on. There are two main EUS scopes. You have a radial scope, which is scanning sort of perpendicular to the scope, and a linear scope, which is scanning more in parallel to the axis of the scope. The purposes are very different. The radial scope, you're using it for staging cancers. You're using it also for defining which layer a particular lesion is coming from. But the linear scope is mainly used to do interventions. With a radial endoscope, it's mainly a diagnostic tool. It cannot do any interventions. With the linear scope here, it kind of shows you the needle going into the tissue. So this is a lymph node that we are biopsying through the esophageal wall by passing a needle into that tissue. So kind of showing in this picture how the needle is sort of going into that lymph node. So in conclusions, you got a basic introduction to endoscopy, how the different pictures look, as well as different tools that we have available. This is very basic in terms of what tools we have available right now. And in ERCP and EUS, there are several more catheters and guide wires, and it just opens up a stent and et cetera that become used. But it's sort of a basic understanding of that. I think I went over. I cannot believe it. All right, questions? Yeah. Yes, you talked about snares and polyp removal earlier, and that there's a difference between hot and cold snaring. And I've read different reports on different preferences that different physicians have. And I guess my question for you is, when you're going in there and you see multiple polyps that might require a different tool, do you typically do a device exchange, or do you just work with what you have and then deal with whatever bleeding or whatever happens after that? What's your technique? Yeah, I think it's a more subjective question. It depends on which endoscopist is performing and what their choices are. I'll just answer what I do typically. Depending on the polyp, whatever it needs, I use that device. So if it requires an exchange of device, I exchange the device into the right tool. If a polyp requires a cold snare to be done, I use a dedicated cold snare for that polypectomy. Now, if you've used a hot snare to do a polypectomy on something, and then you see another polyp down in a different part of the colon, that you can use cold snare, you can use a hot snare as a cold snare as well, right? You just don't apply the heat, and you can use it as a cold snare. But there are special properties of the cold snare which are very useful in certain types of polyps. So it's a little subjective question, but that's kind of in general. I would say majority of us would probably do the same thing. Let's say if something requires a forceps rather than a snare, they would change the device out. All right, oh, one more, yes. Hi, you mentioned you could use Botox to relax the esophagus. Would you use that as a treatment for like EOE or GERD or something like that? So GERD is when there is relaxations, too much relaxations, right? So you definitely don't wanna use that in GERD. And EOE is not necessarily a muscular disease. It's more of an inflammation and a scarring process. So in there, again, Botox doesn't tend to work very well. So it's mostly for muscular disorders like spastic disease of the esophagus or achalasia. Yeah. For using Linear US, how many, like what percentage of the endoscopist population would you say are actually familiar with doing FNA, FNB, and these types of procedures? So most endoscopists who are trained in EUS, I would say would do the FNAs. What percentage would you say are trained in the US? The general population of endoscopists or advanced endoscopists? Advanced endoscopists, I need help from the faculty. I would say maybe about 30% of our GI. Can I say that? Yeah. So like if you take a group, right? If you take any practice group for that matter, you'll see maybe one or two advanced endoscopists or maybe more, depending on the size of the group, obviously. We are six advanced endoscopists in our group, of a group of 44 gastroenterologists. So, and what's the- So that's roughly, yeah, there are 1,300 approximately interventional endoscopists in the US now, you know, and I'll say 25 to 30%. 25, 30%. And most of us, you know, who are trained in doing EUS will be doing FNAs and FNBs. Thank you.

gastroenterologists

ERCP

EUS

upper endoscopy

colonoscopy

biopsy forceps

therapeutic interventions