As Dr. Tierney alluded, we do have some very nice devices, tools as it were, that help us to diagnose and also to treat the various disorders that we see in the gastrointestinal tract. Some of these are newer, but many have been around for a long time and the fact that some of these devices haven't changed a whole lot in decades is a testament to how powerful these devices are and how well designed they are. They could be that old and still not have been replaced by new technology. So here we go. This is really exciting stuff. So the objectives of this lecture are twofold. To look at general gastroenterology and what devices we use in that aspect of treating GI disorders and diagnosing and treating them and also to give you a little glimpse into interventional gastroenterology where we're actually able to do some complex things with endoscopic devices to actually treat disease states. So in general gastroenterology, we rely greatly on upper gastrointestinal endoscopy to look at the upper GI tract, colonoscopy to look at and treat the lower GI tract, along with some devices, accessories, or tools as it were, that we generally introduce through these scopes, although sometimes also side saddle alongside the scopes to meet out diagnosis and treatment. And also in interventional GI, which uses some specialty scopes to perform endoscopy in the bile duct and the pancreas duct in ERCP or endoscopic retrograde cholangiopancreatography and endoscopic ultrasound or EUS, where there's actually an ultrasound machine built into the tip of an endoscope. Those two scopes are rather specialized and you'll see how in just a moment. So in upper endoscopy or upper GI endoscopy or upper gastrointestinal endoscopy, those are synonymous terms, we're examining and potentially treating disorders in the upper GI tract. And the upper GI tract, as you know, includes not only the esophagus, but also the stomach and the very first part of the small intestine, which is the duodenum. So an upper GI endoscopy or esophago-gastroduodenoscopy, abbreviated EGD, is really examining not just one organ, but actually examining three separate organs. As such, when we document an endoscopy report or op note, it really is three separate notes in a sense. We will describe what we see and do in the esophagus, and then we'll describe what we see and treat in the stomach, and then do so in the duodenum as well. So sometimes this can be a rather detailed and involved note when we're examining the upper GI tract. An additional note is that while we frequently use the term upper endoscopy or upper GI endoscopy synonymously with EGD, it's in fact a more general term because sometimes we're examining not just what is examined in a standard EGD, which would be examining the esophagus, the stomach, and really the first and second portions of the duodenum. The first portion of the duodenum is the bulb, and then the second portion is here, this curved part of the duodenum. And a typical upper GI endoscope, the scope that we use for an EGD, can reliably get down to the second portion or the very beginning of this third portion of the duodenum, the transverse duodenum, but rarely gets past, say, the midpoint of the third part of the duodenum or this fourth portion of the duodenum near the ligament of trites. To visualize those areas reliably or to see some of the jejunum, one might need to perform an enteroscopy, and that can be done with a colonoscope, or it can be done with a dedicated very long scope called an enteroscope. With a colonoscope, you can typically see all of the duodenum and sometimes a small portion of the jejunum. With a dedicated enteroscope, one can reliably see a substantial portion of the jejunum. I bring that up because technically speaking, upper GI endoscopy includes enteroscopy. So technically, upper GI endoscopy is a rather more general term than EGD, and EGD is sort of a subset of upper GI endoscopy because upper GI endoscopy includes EGD, and most upper GI endoscopy, in fact, is EGD. But occasionally, an endoscopist might perform an enteroscopy using a colonoscope simply because the scope is longer than a standard upper endoscoping can see farther down or a dedicated enteroscope. Before I leave that topic, I'd like to ask if you have any questions because I'd like to clear up anything that seems unclear to you. Yes, sir? Is the vision different if you're doing an endoscopy? That's a really good question. And the answer is yes, sometimes, particularly if one is doing a deep enteroscopy with, say, an enteroscope, which often has an overtube and can look far down into the jejunum. That would be rather uncomfortable to perform with only light sedation, which could make it difficult and unpleasant for the patient and also for the endoscopist, lead to a less than optimal examination. So you're right. That's frequently done with anesthesia assistance at many institutions. Thank you for asking that question. Other questions? Or is there anything that's unclear that I could explain better? Okay. Hope that helps. The indications of upper GI endoscopy are manifold, but some of the most common ones include upper abdominal pain or discomfort. Pain doesn't mean the same thing to everybody, and so discomfort can be kind of a rather more general term that we use with patients so that it's a little bit more all-encompassing. Because some patients will only think of sharp pain, for example, as being pain and might not think of a discomfort that you might think of as an ache as being a type of pain. So sometimes we use the term discomfort instead. Gastroesophageal reflux disease, sometimes abbreviated GERD, which we pronounce GERD, is extremely common and is probably the most common indication in GI practice today for performing upper GI endoscopy. Dysphagia is difficulty swallowing, which is different from odynophagia, which is a term that's not on that slide, O-D-Y-N-O-P-H-A-G-I-A. Odynophagia means painful swallowing, which would be another indication or reason to perform an upper GI endoscopy, as would be iron deficiency anemia. If someone has an iron deficiency anemia, you want to know if they might be losing blood in the GI tract, and particularly the upper GI tract can be a common location for the abnormal loss of blood for various reasons. Actual signs of bleeding, overt signs, whether that's vomiting red blood or passing red blood in the stools or passing dark blood or black blood, which has been subjected to digestion in the upper GI tract, which can make blood turn jet black. That's called melanin. Esophageal varices, which are varicose veins that can develop in the esophagus, usually as a result of portal hypertension, which can happen in the setting of liver disease and for other reasons. Not only to look for those, because if a patient has them, there might be things that can be done to prevent those esophageal varicose vessels from breaking open and bleeding, or to frankly treat bleeding esophageal varices. We sometimes perform upper GI endoscopy to remove things that a patient has swallowed, either accidentally or otherwise, that might cause problems if they're allowed to remain in the GI tract or pass lower into the GI tract. They might injure the GI tract or block the flow of contents, liquid or food, and food impactions, so where somebody has swallowed food that then doesn't move through the esophagus and can get stuck there, that can be very dangerous, because then when you swallow saliva and it doesn't go down, you might then bring that saliva back up and then aspirate that into your lungs, and that can be very harmful. So we sometimes use an upper GI endoscopy to remove foreign objects or impacted food from the esophagus or farther down in the upper GI tract. Conversely, we sometimes need to feed a patient who can't eat enough to meet their nutritional requirements, so we might actually use an upper GI endoscopy to aid in placing a feeding tube either into the stomach or farther down into the intestine. For patients who have issues with their stomach actually handling food, sometimes we actually have to pass the tube into the small intestine and feed at that location. Now the insertion of a forward-viewing endoscope, whether that's an upper GI endoscope, an EGD scope, or a colonoscope when performing a scope from below, these are scopes where the lens sees forward so that the view that the scope is giving you is analogous to the view that the person, say, driving a subway train might see from the driver's seat. Since these scopes see what's in front of them, there's absolutely no excuse for driving that scope without seeing in front of you directly. And so we pass these scopes with direct visualization. We don't pass them blindly, although there are spots where we might momentarily lose that view of the lumen or the view of the tunnel. So we perform forward-viewing GI endoscopy, including EGD, under direct visualization. When we do, we first insert the scope through the mouth over the tongue. And then as we round the base of the tongue, we get this view of what's called the hypopharynx. And this is the spot where the back of the throat, so to speak, divides into the airway, which is ventral towards the chest, and the esophagus, which is dorsal or towards the back. So it splits off. So if the front of the body is this way and the back of the body is that way, the airway is right here, and the esophagus is tucked back in here. So when we pass our scope through the mouth, over the base of the tongue, to the place where the airway and the esophagus split off here, where we're aiming is actually right here, not there. If you're a lung doctor, you might be aiming here. But if you're a gastroenterologist, this is the sweet spot. As you can see, these are the vocal cords right here. We actually get this view frequently, but we don't actually go through there. That's not our job. It is for us, but not if you're a lung doctor. Then this is the sweet spot. So these are the vocal cords here, and this is actually the bronchus. We try not to go in there. And then there is the epiglottis, which is kind of like a trap door up here, which closes that airway opening when you swallow, right? Because otherwise, if your epiglottis didn't close the airway, you would actually accidentally aspirate food into your airway and hopefully cough it out. There are disease states in which that trap door, that epiglottis, which you can't actually see well in that picture, doesn't work well, such as in patients who've had radiation to their neck area for cancer in that area, and that can cause problems with food and saliva getting into the airway and even result in pneumonias. So that trap door, that epiglottis that's under involuntary control that closes when you swallow, is actually a really important safety device built into your wonderful body. These little areas here that almost look like a hole, although it's not a hole, it's kind of almost a sack, are called the piriform sinuses. And the scope may have a tendency to go into those areas. So for a new endoscopist, it's a little bit of a challenge and an art to actually nudge the scope away from the piriform sinuses and try to stay midline to get through the upper esophageal sphincter muscle, the UES, and into the esophagus itself. This is all very important. Any questions at this point? So as we traverse the body of the – we've just gone through the upper esophageal sphincter and we're traversing the lumen of the esophagus with the scope. And as we transition to the distal esophagus, the lower esophagus, we come to that area where the esophagus drains into the stomach and this is the esophagogastric junction, the EGJ, or some refer to it as the gastroesophageal junction if you're more of a stomach fan than an esophagus fan, I guess, or GEJ. The EGJ and the GEJ are synonymous. They're the same thing. It just depends on, you know, are you a Cubs fan or a Sox fan, are you an esophagus fan or are you a stomach fan? You don't have to raise your hand and let me know. But they mean the same thing and you'll hear both of those terms batted around. They're both correct. In most individuals, adult individuals as opposed to the measurements that Dr. Lightdale was sharing with you for infants and kids, in most adults, the esophagogastric junction is located somewhere around 35 to the 40s past the incisors. So the incisor teeth are what we're talking about, your two front teeth. In some individuals, it can be as far as 45 centimeters distal to the incisors. So as Dr. Lightdale alluded earlier, there can be an 8 to 10 centimeter sort of a normal range if it were for the length of the esophagus in adults. The squamo-columnar junction refers to the junction of the squamous mucosa or lining tissue of the esophagus, which is paler, and the pinker or redder colored mucosa or lining tissue of the stomach. In normal anatomy, the squamous lining of the esophagus meets the columnar lining of the stomach at the top of the stomach, and the top of the stomach is defined as the top of the rugal folds, the proximal end of the gastric folds. That is anatomically where the stomach begins and the esophagus ends. So here's a gastric fold, a rugal fold. Here's another rugal fold. Here's another one. You can see where that fold flattens out right here, fold flattens out right here, fold flattens out right here. I know it's a little subtle, but that's very important because while in normal anatomy, the squamous lining of the esophagus ends at the same spot as the tops of the rugal folds of the stomach, in some disease states, in some disorders, as Dr. Lightdale will teach you in a few minutes, they do not meet at the same spot. The squamous lining of the esophagus might end upstream from the tops of the gastric rugal folds, and that would not be the normal state of health, and she will school you on that shortly. But in normal anatomy, this Z line, as we call it, which is where the squamo-columnar junction is, is the same location as the tops of the rugal folds. Does that make sense? It's a little subtle, but extremely important, as you will learn in Dr. Lightdale's talk. Questions before I leave this? So we just went over that, and the next few pictures are going to show you a schematic of where the scope is looking. Here the scope is in the distal esophagus looking at the EGJ or the GEJ, and this is the actual view that you get with a scope. So here's a gastric rugal fold, gastric rugal fold. The rugal fold is ending right where the Z line or the squamo-columnar junction is, and so this is the normal view. Sometimes you will see that where the diaphragm is impacting the esophagogastric junction might not be exactly at the location of the squamo-columnar junction, and to some extent or other, that may demarcate what's called a hiatal hernia. I'm not going to go farther into that because this is a normal anatomy lecture, but we'll hear more about that in a few minutes. The upper stomach or the proximal stomach looks like this. This arched area, which acts sort of as a reservoir and is important in liquid emptying, is called the fundus, as you learned. This area, again, as Dr. Lightdale mentioned, is the cardia, right below the EG junction. The majority of the stomach is the body, and then the lower or distal part of the stomach is the antrum. Sometimes you'll hear about this area right before the pylorus being called the pre-pyloric area or the pre-pyloric antrum. Pre-pyloric is just a subset of the entire antral portion of the stomach, which is that portion distal to this angulation, which is the insessura angularis. When you look down into the body of the stomach with a scope, this is the greater curve or the greater curvature. This is the lesser curve or the lesser curvature. When you look to the left, that's the front or the ventral portion, the anterior abdomen. This would correspond to the back or the dorsal portion. With an endoscope, since there's a lens involved, the image is flipped, so what's up is down and what's down is up. It's not all that important when you're looking with an upper GI endoscope, but in some other situations it can be important to remember that. You don't need to. Looking at the distal stomach, this is looking towards the antrum from the body here. The pylorus is tucked right in there, and this is that angulation, which is called the insessura or the insessura angularis. Here the scope is looking right at the pylorus, which is the opening between the antrum or pre-pyloric antrum of the stomach and the bulb of the duodenum here, which is also called by some the first portion of the duodenum. It's actually the most common place for ulcers to occur. The pylorus is a strong muscular ring, and that muscular ring is there because the stomach has multiple functions. One of them is to act as a reservoir so that you can eat your meal and get moving. You don't have time to spend hours eating your meal. The stomach is a reservoir so that you can store that food, and over time after you eat, the stomach takes that stored food and it grinds or mills it into tiny little particles of a millimeter or two in size. Your pylorus acts almost like a filter so that when it's closed, the stomach can grind against that closed door, and then it squeezes and jets only little particles through the pylorus so that the larger ones can continue to get milled. The reason for grinding and milling the food is to increase the surface area so that the digestive enzymes can get to as much surface area of the food as possible. It's all about efficiency and not wasting those nutrients. Does that make sense? And the pylorus is key to that. Every now and then, it opens up large to let things that can't be further milled through as basically fiber and waste. Here's a view of that duodenal bulb or the first portion of the duodenum here. It looks like this. Sometimes you'll see little bumps like this one right here. They're called Brunner's glands. They make bicarbonate to neutralize stomach acid. And then as you go farther down to the second portion of the duodenum, this C-shaped part of the duodenum, sometimes called the duodenal sweep, sometimes you're able, with a forward viewing scope, to see the major papilla, which, as you learned already, is the joint opening of the bile duct and the pancreas duct. And you're looking here towards the third portion of the duodenum, which, because it goes across the abdomen, is sometimes called the transverse duodenum. Now we didn't get the whole look at the stomach because you know how when you walk into a room through the doors, you can't see what's behind you. To see what's on the walls that the door's on, you actually have to turn around to see what you already passed. Well, the same thing as you go from the narrow esophagus into the capacious stomach. You can't see the fundus going in, so you have to turn around. And the way that the scope turns around is called retroflexion. So by retroflexing the scope, you're able to see the fundus and this part of the cardia much better and in greater completion than you would be able to see with an end-on view only. Does that make sense? So a retroflexion view of the fundus and cardia is imperative in any upper GI endoscopy. Otherwise, one would miss seeing those areas and potentially miss something that needs to be diagnosed or treated. So that is called retroflexion. And it's properly done either as you're withdrawing the scope from the duodenum back into the stomach or upon entering the stomach before entering the pylorus to get a complete view of the stomach before looking at the duodenum. Either is correct. Now we're going to transition from the upper GI tract to the large intestine. We were saying that to scope the large intestine, we would perform what's called a colonoscopy. Now there are different parts to the colon or large intestine. Large intestine and colon are synonymous terms. The colon begins where the ileum, the final portion of the small intestine, enters the colon. And the ileum enters the colon at the ileocecal valve, which is right where the cecum transitions to the ascending colon. There's a little appendage called an appendix, which is a blind sac, if you will, that's attached to the cecum. The cecum is just this part that is, so to speak, upstream from the ileocecal valve. So stool, fecal matter dumps in here from the ileum to the ileocecal valve right where this cecum is. Downstream from the cecum is the ascending colon. And it's called that because stool ascends from the pelvic area up to the very top of the stomach. Then goes down the transverse colon, which is called transverse because it goes across the top of the belly. And down the descending colon because this part is called the descending colon because it goes down. To the sigmoid colon, called that because it's sigmoid or S-shaped, it's curved. And then the rectum, finally, called that because it's erect. It's the up and down, up-down portion of the colon, the very final part of the colon. And then through the anus out into the wild blue yonder. That's the normal lower GI tract anatomy. Colonoscopy is the endoscopic examination of the colon performed usually by going through the anal orifice up the rectum and then through the colon. And then many times, we can get a view of several centimeters of the terminal ileum as well. Now, the colon stores feces. And as a result, if we don't cleanse the colon before we perform colonoscopy, we wouldn't be able to see the vast majority of the surface area. And in fact, by pushing a scope through areas where we can't visualize the lumen because it's blocked with stool could be unsafe. And so we typically have the patient prepare for the colonoscopy by observing a liquid diet and then using laxatives or high volume colon cleansing agents to cleanse the colon before we perform an elective colonoscopy. One of the important indications of colonoscopy is in the diagnosis and management of colorectal cancer. As you're probably aware, colorectal cancer frequently starts as a polyp, which is a small pre-malignant condition. Some of those can grow larger, and as they grow larger, develop chromosomal abnormalities that can then lead to cancer, which is originally contained in the polyp. But as the cancer within the polyp grows, can invade the lower areas and even travel to other parts of the body, which we call metastatic cancer. Those usually can't be cured. So in order to sort of stop this progression, we want to screen and survey patients because if you can nip a polyp like this or even this one in the bud by removing it with a colonoscope, you can prevent that progression from adenoma to intramucosal carcinoma that's contained, prevent that from progressing to these invasive forms of cancer, particularly the ones that could metastasize to other parts of the body and become incurable. Is that clear? So preventing this progression is the whole reason for performing screening and surveillance colonoscopy. Screening specifically refers to performing colonoscopy for patients who are without symptoms. If they have symptoms, and those symptoms are what are making you perform the colonoscopy, that's diagnostic colonoscopy. By definition, if you're screening, these patients do not have symptoms attributable to the colon. Is that clear? Now that screening might be in normal risk individuals or might be in high risk individuals such as patients who have a family history of polyps or colon cancer or patients who have conditions that may predispose to a higher risk of developing colon cancer such as inflammatory bowel disease, IBD, ulcerative colitis or Crohn's colitis. However, if we're calling it screening, whether they are normal or high risk, those individuals should not have symptoms that could be attributed to the colon. If the symptoms are what's making you scope, that's diagnostic colonoscopy, not screening. So screening is for asymptomatic patients. Surveillance is a little different. Surveillance is still the asymptomatic patient, but these are periodic examinations when you've already found disease. So somebody who's had polyps before or had colon cancer before, they're not normal risk and they've already presented with the disease. So you know that they're at high risk for having polyps again or developing cancer. And so for those patients, we call that surveillance. Now there are a number of indications for diagnostic colonoscopy as well as for screening. Those include abdominal discomfort or pain, rectal bleeding, iron deficiency anemia. With rectal bleeding and iron deficiency anemia, we want to know are those coming from undiagnosed colon cancer? Are they coming from inflammatory bowel disease? Or are they frankly coming from somewhere other than the colon? We need to know. So a colonoscopy would be so revealing. We might actually be concerned about inflammatory bowel disease, ulcerative colitis or Crohn's disease, diarrhea, or working up some sort of abnormal finding on imaging, such as a CT scan that maybe was done for a non-GI reason happened to show a lesion in the colon. A colonoscopy might be required to determine what that is, if anything. There might be therapeutic reasons where we're actually going in with a colonoscope to treat, whether that's to remove polyps, to look for and treat bleeding. There might be a twisted bowel, a volvulus, and you can actually untwist that with a scope. That's called a reduction of a volvulus. We might decompress the colon where things aren't going through, which we might even do by leaving a tube behind. Or if someone has an obstruction, such as from a colon cancer, we might place a stent to overcome that obstruction. There are a number of accessories we can pass through the scope, including biopsy forceps, snares to remove polyps, baskets and nets to retrieve things like polyps that we've cut off. We might use injection needles to inject medications or tattoo. We might use clips to close defects, sometimes that we create, or to prevent polypectomy sites from bleeding. We might use electrocoagulation or cautery probes to treat bleeding sites. Or we might use rubber bands to ligate vessels. Biopsy forceps are simple and commonly used. They come in different forms. We usually use them to obtain tissue. Rarely, we might use them to remove a small polyp, although our practice has changed over the years, and we tend to use snares even to remove small polyps. They come in different sizes and shapes. Snares are wire loops that go through, typically, a plastic catheter. And they're primarily used to remove polyps, although we sometimes use them to grab foreign objects or food impactions to help in their retrieval. And they also come in different configurations with various special features. And you may see some of these variations on the theme during the lab. The technique is rather straightforward. You put the loop over the polyp, and then you tighten that loop against the plastic catheter. And when you do that tight enough, you can cut it off. And most of the time, we do this without electrical current. But we might use electrosurgical current, particularly for larger polyps that we may not be able to successfully cut through with just a cold wire. Here is an image of a hot polypectomy. So we're going to get the loop around and then tighten the loop against the plastic catheter. You'll see the polyp on the petal. And you'll see the tissue whiten. And that's where it's been burned and cut through. And then that polyp can then be snared again and removed. Here's another example of that. Tightening down on that, and then current is applied. Sometimes you'll see a little bit of water vapor, looks like smoke, arising from the tissue. And the thicker ones take longer to cut through. See the whitening of the tissue as it burns. And then that can be successfully removed. And that's the polypectomy site. Sometimes we'll use a snare that has a cloth that's stitched onto it. That's called a removal net. Or there are similarly shaped baskets, which are less often used to remove, as I mentioned earlier, polyps or other foreign objects that are too large to suction through the scope. If a large polyp is removed in one piece, we pick up the resected polyp with the snare and drag it behind us. If we have one large piece and multiple small pieces, we suck the small pieces through the channel and then pick up the large one with the snare and drag it a few centimeters behind so we can continue examining. There are various injection needles, which are pretty self-explanatory. We use these frequently to inject medication to reduce bleeding, prevent bleeding, stop bleeding. But sometimes also to inject dye or tattooing agents to mark places that we might need to look at again. Sometimes we use them to inject saline or other fluid, epinephrine, sometimes tinted with dye, to take flat polyps and raise them up so that we can actually successfully capture them with a loop snare. This is sometimes called endoscopic mucosal resection, or EMR. There are fancier versions of that called ESD, which you'll see later. Sometimes we're tunneling under here to actually incise the muscle when we do a poem. We sometimes also inject Botox into the muscle, particularly at the lower esophageal sphincter for patients who have a disease process where that sphincter won't relax and so they have trouble swallowing or dysphagia. You'll see a needle here injecting fluid under the mucosa into the submucosa to lift that polyp up. That serves to make it stick out so you can grab onto it with a snare. It can also act as a heat sink to reduce the burning of the muscle tissue below when you use cautery to take out a polyp. It can also be used to bring something that's away from you closer to you to give you better access at capturing and then removing that tissue. See how nice that is? Can also reduce the risk of bleeding in the same way that if you cut yourself, you could put pressure on that cut with your finger. Well, the pressure from the fluid injection can slow down bleeding to help you better focus your treatment at the bleeding source. Several clips called hemostatic clipping devices are sometimes used to pinch vessels or clip them shut so that they stop bleeding or to prevent them from bleeding. Sometimes when we take a larger polyp off, we might close that defect to reduce the risk of post polypectomy bleeding. And that's frequently done with clips, which come in different sizes and shapes from different manufacturers. Sometimes instead, we'll use heat generated by electrical current to press the front of the vessel against the back of the vessel and seal the vessel shut so that that vessel clots because of lack of flow, which then leads to permanent stoppage of the bleeding and prevention of bleeding in the future. Argon plasma coagulation is a more superficial way to obliterate tiny vessels or capillaries. This has ionized argon gas traveling through the catheter. And that ionized gas is the last way that the current is transferred to the tissue. And those small vessels, such as in gastric antral vascular ectasias or angio dysplasias, can be burned and obliterated. We also sometimes apply rubber bands to larger vessels, like esophageal varices, which are varicose veins in the esophagus we talked about, or sometimes even for hemorrhoids. We just apply the suction through the scope. The varicose vein is brought into this cap here. And then as we turn this crank, one of the rubber bands is fired over the vessel. And it is then, over time, obliterated. And the blood clots. And the bleeding stops. Or you can prevent future bleeding by obliterating that vessel. And here's a schematic of that. ERCP is endoscopic retrograde cholangiopancreatography. This is endoscopic examination of the bile duct and the pancreas duct, which Dr. Tierney alluded to earlier. And we do that by using a dedicated scope that has a lens on the side, since the major papilla is on the sidewall of the duodenum. And we will then inject dye into the bile duct and the pancreas duct under X-ray and use the X-ray imaging to guide anything that we do in those ducts thereafter. Here you can see a catheter inserted through the duodenoscope into the bile duct, presumably to get rid of that bile duct stone. This is what the image looks like under X-ray. The dye has been injected into the ducts. And as you can see, this has a lens on the side. And it has an elevator which is actuated with a thumb trigger that will bring that device, the catheter device, up into the view of the lens. So here we're injecting dye into the bile duct and similarly into the pancreas. Both share the same opening. In endoscopic ultrasound, we said that this is also a dedicated scope. Here an ultrasound machine is built into the tip of this special echo endoscope. And using this, you can identify all five layers of the GI tract wall, and sometimes even meet out treatments. The indication most commonly for endoscopic ultrasound is diagnosis and staging of cancer. Also obtaining tissue with needle aspiration or needle biopsy, evaluation of lesions underneath the lining of the GI tract, diagnosing gallstone disease, and sometimes draining pancreatic pseudocysts, or frankly, other therapeutic uses of EUS, which we can discuss later. There are two different kinds, radial and linear. The radial allows you a 360-degree view, but only to look, typically used in the esophagus or the rectum. And then the linear echo endoscope, which actually allows you to see devices such as needles that are passed through the scope, that pass through the view of the echo endoscope, and allow you to safely inject or obtain tissue. Here you can see a lymph node, a periaortic lymph node being biopsied under echo endoscopic view. So this serves as an introduction to GI endoscopy. We're only scratching the surface. There's lots more exciting detail. Gives you a basic understanding of the core of upper and lower endoscopy, ERCP and EUS, and a few of the accessories that we use through the scopes. Thank you very much. Thank you.

gastrointestinal endoscopy

diagnosing GI disorders

treating GI disorders

upper gastrointestinal endoscopy

biopsy forceps

polyp removal

endoscopic retrograde cholangiopancreatography

endoscopic ultrasound