All right, now we get to have some fun with some of the tools and toys that we get to use as gastroenterologists. And this will really be a very important introduction for some of you that are new to the GI space, and particularly if you're new to GI endoscopy. When we go into the Bioskills Lab later today, the material we talk about right now will provide a framework for that discussion. Okay, I'm going to skip over that one. Let's go to this one. Upper GI endoscopes can be used in the lower GI tract, and colonoscopes can be used in the upper GI tract. Is that true or false? Oh, there we go. So the answer is true, that you can use these, and we frequently do in practice, and we can chat about that when we're in the lab later today. Next, in most GI endoscopes, optical fibers and electrical signals from digital chips are used to carry both light to the scope tip and images to the image processor and monitor. And the answer there is yes, true. In the old days, we used to have fiber optic instruments where it was all just fibers carrying both the light and the images, but now we have digital instruments. So our goals today, our objectives, are really to review the devices we use in general GI endoscopy, which includes upper endoscopy, or EGD, and colonoscopy, and also to give you a brief introduction to what we call advanced endoscopy or interventional endoscopy, which includes ERCP and EUS. So upper endoscopy includes an examination of the esophagus, the stomach, and the first part of the small intestine, the duodenum. And the term we use is esophago-gastroduodenoscopy because we're inspecting with a scope all three of those areas. So we abbreviate that EGD. Why do we do upper endoscopy? Well, there's a whole list of appropriate indications for somebody that has digestive symptoms or disease states that require us to do an upper endoscopy. And this is a brief, perhaps the most common reasons that we investigate patients with symptoms. And that includes upper abdominal pain or discomfort that's unexplained. Longstanding acid reflux in certain patients would perhaps warrant an upper endoscopy. Somebody with dysphagia, a sense of food getting stuck, not traversing the esophagus appropriately should have an upper endoscopy. Iron deficiency anemia, where the body is low in iron, suggests there may be a reason in the digestive tract to chronically losing blood. And so we want to perhaps look in the upper digestive tract for diseases that would be associated with chronic blood loss. Likewise, any sign of bleeding, vomiting blood, or passing black stools from below would be a potential sign that there's more acute ongoing blood loss from the digestive tract. Esophageal varices we'll talk about in a later lecture sometimes need first to be confirmed and diagnosed with an upper endoscopy and sometimes treated. And occasionally food will get stuck in the esophagus or there will be a foreign body in the upper digestive tract that needs to be retrieved because it could cause harm to the patient. And we can do that via upper endoscopy. And finally, we can place long-standing or permanent feeding tubes in patients using upper endoscopy. So when we insert an endoscope, we first have to go into the mouth. And this area of the body is a very complicated anatomic area. There are lots of structures in the head and neck area, but this is what we see when we put the endoscope into the mouth and into what we call the hypopharynx. And we're looking down at the airway. This is the vocal cords, and we don't want to go there. That's where our pulmonary colleagues go, but as gastroenterologists, we don't want to go there. We actually want to go back here near the piriform sinuses to get to the esophagus. But we see this most of the time when we go in for upper endoscopy. So when we're inspecting the esophagus, we talked a little bit earlier, Brooke talked about the Z line at the junction of the esophagus and stomach. And here you can see the nice salmon-colored mucosa of the stomach, whereas the pearly white lining is normal squamous mucosa of the esophagus. And why is it called the Z line? Well, it's called the Z line because it's often irregular like this. You can sort of see it almost looks like a letter Z right there if you were to trace that out. And that's why it's gotten that vernacular. We can also define this because you can see the top of the gastric folds. You can see a fold there and a fold there. That defines that stomach as opposed to esophagus, which is a tubular structure with no folds in it. Here's another good example of the squamo-columnar junction. You can see it's a little bit more regular and straight compared to the previous patient. But again, you can see the stomach folds with salmon-colored mucosa here and the pearly white lining of the esophagus. And if we didn't see this squamo-columnar junction at the bottom of the esophagus, if we saw that salmon mucosa extending up higher, that would be a sign that we're dealing with Barrett's esophagus, which we'll talk about later. As we drive the instrument, the endoscope, down into the stomach, you can see we now are seeing the rugel folds along what we call the greater curve of the stomach. And this is the lesser curve of the stomach. And it's usually have less prominent folds on this side of the stomach. We keep advancing the instrument further down into the body of the stomach and keep going. And we can visualize the pylorus, which is the muscular sphincter at the end of the stomach controlling the emptying of contents into the duodenum. If we keep advancing our scope further, we enter into the duodenal bulb. And again, the lining here is distinctly different than what we saw in the stomach. And we keep going into the second portion of the duodenum, and we can most of the time identify the major papilla or the ampulla vata, which is where the bile duct and the pancreas duct drain secretory contents into the intestine to help us digest our food. Both of the bile and the pancreatic juices are designed to help mix with our food and break down our food so it can be more appropriately and more efficiently absorbed down further in the small intestine. So this is, when we're doing ERCP, this is how we can access the bile duct and the pancreas duct. We come back in the stomach a lot of, most of the time, we should be what we call retroflexing where we can turn our instruments. Our instruments can turn in very sharp angles, more than 180 degrees, and look at the entrance of the scope as it's coming into the stomach so we don't miss any pathology way up high in the stomach. And this is probably the spleen indenting the stomach up here. Okay, now for a colonoscopy, we are using different instruments. As we alluded to in the question, we can use both upper endoscopes for the colon and colonoscopes for the upper digestive tract for specific indications. But a colonoscope is typically longer and a little bit larger diameter than an upper endoscope. And it's longer because it has a longer course to traverse. So here's, again, an anatomic orientation, which we've already discussed, of the colon. For colonoscopy, it's really important that we actually have a cleansing of the colon. The patients have to take a bowel preparation to clean their bowels out. Otherwise, we're not going to be able to adequately visualize the lining of the colon. And that's really the whole goal, is for us to adequately visualize the lining of the colon to detect disease, detect polyps, detect cancer, et cetera. And if it's not adequately prepped or cleaned, it's not going to be an adequate examination. So this bowel preparation is really pretty key before we even get started with a colonoscopy. But the goal is to inspect the whole colon. And in fact, we can inspect the very end of the terminal ileum. So as Gauri was mentioning, we can inspect the upper part of the small bowel with an upper endoscope. And we can inspect the end of the small bowel, or the terminal ileum, with a colonoscope. Now why do we do colonoscopy? A whole list of indications, similar to what we mentioned with upper endoscopy. But by far and away, the most common reason is colorectal cancer screening or surveillance for patients that have known history of precancerous polyps. So screening refers to the situation where someone has no history of polyps. They don't have any symptoms. They're really just doing it as a baseline examination. But once you have detected precancerous polyps, you go into a surveillance program because you're at higher risk of getting those polyps in the future. And so your interval for a colonoscopy is likely going to be more frequent than a pure screening examination. But the whole goal for screening or surveillance is to detect polyps. And here you can see that they vary over time. Small polyps will develop into larger polyps and eventually into early cancers and then advanced cancers. And our goal with colonoscopy is to identify lesions earlier so that it can be removed with the endoscope and interrupt this cycle and prevent colon cancer or lower the risk of colon cancer. Other reasons we might do colonoscopy are included here. And that includes rectal bleeding, iron deficiency, anemia, again, for the same reasons we do upper endoscopy. If there's some process or disease state that's leading to chronic low-grade blood loss, we want to detect that and potentially treat it. Inflammatory bowel disease. Anybody that has symptoms of chronic diarrhea or chronic bleeding or chronic abdominal pain where we're concerned about a chronic inflammation of the colon or just the small bowel, we will want to do a colonoscopy to investigate and diagnose that. Many, many causes of diarrhea and many of those diseases can be diagnosed with a colonoscopy. And so that is often, diarrhea is often an indication for colonoscopy. And then finally, abnormal imaging. So a patient gets a CAT scan and they find, incidentally, that there's something wrong with the colon on the CAT scan. That would be an indication to do a colonoscopy. There are therapeutic reasons or reasons for us to intervene during colonoscopy and that includes, as we talked about earlier, removal of polyps to interrupt that cancer cycle. Anybody that has bleeding, acutely or chronically, we can intervene with various devices and tools, which we'll talk about in a minute, to help stop that bleeding. Volvulus is a twisting of the colon that happens, not commonly, but it does happen, it's often in elderly individuals. And when that colon becomes twisted, we can actually go in with a colonoscope and untwist it. And when it is twisted, it often results in a blockage of the colon. So by untwisting it, we can relieve that blockage. And then, very occasionally, there'll be patients that have just, usually critically ill patients in the hospital that have very distended colons because their colon just isn't working properly. The peristalsis is not working and we can go in with a colonoscope and take all the air out and decompress the colon. So there are a number of tools and devices that we can use during endoscopy, both upper endoscopy and lower endoscopy. And this just gives you a very brief sampling of some of those devices. And we'll cover some of these as we go along. So this is a biopsy forcep. And really, the purpose of this device is to obtain small pieces of tissue to send to our pathologist to help us understand what the disease state is when they look under the microscope. We can also remove very small polyps with these biopsy forceps. They come in various sizes and shapes. You'll notice some of them have a spike in the middle of them. And the reason for that is designed to, after you take the first bite, that spike holds the tissue in place on the forcep and you can grab a second bite. So you can get two pieces of tissue with one pass of the instrument. You'll also notice there's different sizes. We have some that are jumbo, some that are large, and then some that are regular size. And some of them have teeth, and some of them are just cupped. Now, polypectomy snares or snares are also tissue acquisition devices that are really designed to get larger pieces of tissue and, more specifically, remove larger polyps or growths. They also come in various sizes and shapes, and they have fairly subtle differences in designs that can help with specific interventions. You can see the different shapes and sizes. So some of them are a little bit more oval. Some of them are a little bit more rounded in shape. There's some that are crescent-shaped. Some often have a duckbill on the tip here. And this one has a spike or a needle on the tip to help ground or fix the tip of the snare while you're trying to deploy it. And you'll get a chance when you're in the lab later today to see these devices and see how they work. In essence, fairly simple, but they do require some expertise in terms of operating them. So the goal with a snare is you really want to get the lasso, so to speak, or the snare all the way around the tissue that you're trying to acquire. Usually your technician then closes the snare into the sheath with a handle outside the devices passing through the working channel of the endoscope. And there's a handle on the other end of the endoscope where the technician or even the endoscopist sometimes can close that snare and snarl the tissue that you're interested in cutting through. And then often while applying cautery, especially in a polyp like this, you would typically apply cautery to cut through the tissue and coagulate the blood vessels. We can remove polyps with what's called a cold technique where we just guillotine without cautery and the pressure of closing the wire on the device actually cuts through the tissue. But with a polyp like this where it has a stalk, we would typically do that with hot or passing cautery or electric current through the snare to accomplish that resection. Okay, in the interest of time, I'll show this video, but we'll pass through the others. Here's a snare where the endoscopist is getting the snare around this polyp, and then they're going to use electrocautery. And you can see there they cut through the tissue. Then they're going to lift that resected polyp off of the tissue. And you can see the coagulated base to that. There are retrieval baskets and nets that we can use to retrieve tissue. In that particular video, you saw them actually grab the resected tissue with the snare, which you can also do and retrieve it all the way out the patient. But we will often use retrieval nets and baskets for removing large polyps, but also, as I mentioned, food will sometimes get stuck in the esophagus or there'll be foreign bodies that a patient has swallowed. And many of us have seen some very interesting things swallowed over time, some we can't even repeat in a public setting. But these devices, these baskets and nets come in very handy in capturing the foreign bodies to be able to then extract them out of the patient. The way these work is it's essentially very similar to a snare with a wire, but there's a netting that covers the whole surface area of the snare. When it's open, a foreign body or device or polyp can be caught or trapped in the net. And then as the assistant closes the wires, you can see that whatever your target is is maintained or captured within the net. It can then be securely removed from the patient. Here's a video just showing the use of a net as it's retrieving a polyp. Injection needles are another important device or tool that we use. Sometimes we're injecting a dye or a tattoo to mark the location of a interesting lesion. So let's say we remove a large polyp and we know we're gonna come back to that area six months later. When it's healed up, we may not be able to tell for sure where it is. So we wanna mark that close to that area with a tattoo so we can find it and inspect closely to make sure that there is no residual polyp there. In addition, if there's a cancer that we find, and we wanna make sure that our surgical colleagues can find that cancer when they're going to operate, especially now in the era of laparoscopic surgery, the tattoo can be seen on the outside of the colon too. And so our surgeons can find that very helpful to make sure that they're resecting the right part of the colon where the cancer is. Like many of our devices, these injection needles come in various sizes in terms of the width of the needle, the gauge of the needle, if you will. And that determines how quickly and how much volume we can inject through the needle. But like all of our devices, they are coming through the working channel of our endoscope. Here's an example of what we might use an injection needle for. We can not only do tattooing, as I mentioned earlier, but we can inject medicines to achieve hemostasis. We can inject epinephrine, typically, to lead to vasospasm and clamping down blood vessels to help us achieve control of bleeding. Sometimes we can, especially in old days, inject medication to treat and ablate varices. But a lot of times we're using the injection needles to lift up the tissue. And here you can see you have a polyp, and the needle is being used to deliver a cushion of material or fluid to lift that polyp away from the wall of the digestive tract so that we can then more safely resect that polyp without injuring the deeper layers or creating a hole in the deeper layers of the digestive tract. And here you can see after we've injected, the cushion is more pronounced, and the lesion of interest is a greater distance away from the wall. And we use this injection technique of creating cushions for many of our interventional endoscopy techniques, including endoscopic mucosal resection, endoscopic submucosal dissection, which are two different techniques of resecting precancerous lesions, or POEM, which is a therapeutic maneuver to go into the third space, which is the submucosal layer. When we talk about third space endoscopy, we're talking about doing interventions within that space right there. Okay, I'm gonna move along, and we'll talk about hemoclips. And hemoclips are another set of devices which has really exploded on the market within endoscopy. There are now numerous companies making hemostatic clips. Most of these go through the working channel of the endoscope. Some are actually designed now to fit on the endoscope, what we call over-the-scope clips. But most of the time we're using through-the-scope clips, these, which is what you see here. We can use these to treat GI bleeding by essentially clamping down on a bleeding blood vessel and tamponading it. And there's a number of different GI bleeding lesions that we can treat in this fashion. We can also use these clips to close mucosal defects. So after we did a resection, say after that previous polyp that we inject, we lift it up, we resected it, there's a defect there. We can use these clips to close the defect to lessen the chance of the patient having bleeding later on. And here you can see a lesion that was polypectomy site that was closed with multiple clips. Electrocautory probes are an important set of devices that we use primarily in controlling GI bleeding. Here you can see what we call a bicap probe or a multipolar electro-surgical probe that will create heat at the site of the lesion of interest and that heat serves to coagulate the blood vessel. A different type of electro-surgical coagulation is called argon plasma coagulation and you'll get a chance to see this a little bit later in the lab. Here, argon gas is passed through the catheter and then an electrical charge is delivered to a tungsten electrode at the end of the catheter and that argon gas serves to carry that charge to the tissue of interest. And we can use that argon gas, particularly that electrically charged argon gas to deliver a current and therefore heat and to the tissue which destroys tissue and or creates hemostasis. So we're using electrocautory to coagulate small blood vessels in this case or destroy tissue. Band ligation is another set of devices which we can use for multiple purposes including banding of esophageal varices which we'll see a cartoon in a moment. And also we can use these bands to lift up tissue to create a pseudopolyp and resect that tissue. And so we have a set of devices that we can use to lift tissue up away from the wall similar to what we do with the lifting with a cushion injecting medicine but by creating a pseudopolyp, we can resect abnormal tissue and so that's why we can use for both banding of bleeding lesions but also resecting tissue as well. Here you can see how a banding device works and in this case, we're banding esophageal varices. Here's the endoscope. The endoscope has a cap on the tip of it and on the cap is a set of bands that is preset around the circumference of the cap. The lesion of interest which in this case is a varix is suctioned up into the cap. Here you can see it's suctioned up and then the endoscopist can deploy or release the band from the tip of the cap and when it does, the elasticity of the band clamps down on the varix and here you can see that ligated varix. The blood flow in the varix then is stopped or ceases and when it stops or ceases, a blood clot forms and that serves to clot off the feeding varices as well or the feeding vessels as well. Okay, let's move on to have a brief review of ERCP or interventional endoscopy and here the goal is to primarily examine the bile ducts or the pancreas duct and as we talked about earlier, we can see the papillae ovata or the ampullae ovata in that second portion of the duodenum. Dr. Abagunde mentioned that there's a minor pancreas duct and a major or main pancreatic duct and here's the opening of the minor duct which is often quite visible in some patients but our interest in most of the time, most of the time when we're doing ERCP is this major papillae which is where the bile duct and the pancreas duct both drain into the intestine. So we can position our endoscope in that second part of the duodenum and actually visualize that opening of the bile duct and we also have the ability to introduce devices into those ducts. We always use x-rays for this procedure because we are relying on x-rays to define the anatomy for us during ERCP. So there's a lot of reasons we can do ERCP. Here, as you can see, the dye that's injected and under x-ray guidance, we can outline the entire biliary tree with a catheter that's inserted into the ampullae ovata. We use this commonly to help treat gallstone disease, particularly if the gallstones are in the bile duct. We use it for stricture dilation, stent placement and we can biopsy inside the bile duct. There's a slight different modification of our endoscopes to help us do this technique. Here, you can see a standard EGD scope where the working channel, which is where our devices come out, the light that helps to shine, provide light to the inside of the lumen and our camera, which is where the optics are for our scope and then there's an air water channel right adjacent to that. This is all looking straight ahead from the endoscope but on a ERCP scope or a duodenoscope, we're actually looking out the side of the instrument. We call it a side viewing instrument. So the optics, the suction channel, the air water channel and the light source is all looking out the side and that's because the orientation of the ampullae ovata is really on the sidewall of the duodenum. So here we see an example of our duodenoscope placed down in the second portion of the duodenum. We're placing a catheter up into the bile duct and here's a beautiful cholangiogram filling up the entire biliary system with x-ray dye and you can actually see partial filling of the pancreas duct on this particular study. We can likewise purposely go into the pancreas duct with this same technique and here you can see a wire catheter that's inserted into the pancreas duct and injection here fills out the pancreas duct all the way out to the tail of the pancreas. Here's a PD stands for pancreatic duct and here we've got partial filling of the common bile duct. We saw a beautiful picture of endoscopic ultrasound that Brooke showed earlier and this technique really combines both endoscopy and ultrasound where we can look at a number of anatomic structures including the wall of the digestive tract and we can define five different layers of the wall of the digestive tract with this technique. We use it to examine the upper digestive tract so staging cancers of the esophagus, the stomach. We can also look at bile ducts, the gallbladder and pancreas with very high resolution ultrasound images and we sometimes use it in the rectum to stage rectal cancer. So the indications for endoscopic ultrasound include as I mentioned staging of cancer and that includes the esophagus, stomach, pancreas and rectal cancer perhaps the most common cancers that we stage but most importantly as we talked about a little earlier we now have the capacity to do therapies and interventions and the earliest one was really the ability to obtain tissue from these target organs particularly the pancreas or lymph nodes or the bile duct that was inaccessible by any other means of getting tissue short of surgery. So now we can use endoscopic ultrasound to obtain fine needle aspirations or even biopsy of abnormal looking tissues or even cysts within the pancreas which can sometimes be precancerous. We can also use endoscopic ultrasound to look at lesions that are in the wall of the intestine. So most of the time when we're doing endoscopy we're looking at, we're trying to diagnose lesions that are on the carpet or on the surface of the lining of the digestive tract. Sometimes there's actually lesions not on the carpet or on the surface but deeper in the wall and endoscopic ultrasound helps us to identify, image those and again also obtain tissue biopsies of those to help understand what they are. We can use endoscopic ultrasound to diagnose gallstone disease and sometimes we're able to find gallstones when a standard transabdominal ultrasound is unable to do so. And we can now intervene with multiple interventions including draining of pancreatic pseudocysts, draining gallbladders, draining the bile ducts, draining abscesses that are usually done previously either surgically or by interventional radiologists and so there's a number of interventions that we can do now with endoscopic ultrasound. This shows you the basic designs of the two fundamental types of EUS scopes or echo endoscopes. The radial scope, the image of the ultrasound is 360 degrees and perpendicular to the long axis of the scope and this is very helpful for staging of esophageal cancer or staging of rectal cancer or even looking at submucosal lesions in the wall of the digestive tract. But a radial scope does not allow you to do a fine needle aspiration or interventions because the plane of the ultrasound is not in the same plane as the axis of the working channel of the scope. Anything you put down the working channel of the scope will just show up as a dot rather than being able to see the whole device on ultrasound. On the other hand, a linear scope does have the ultrasound plane. Usually it's about 180 degrees so it's not 360 but the important part of this diagram shows you that the ultrasound plane is in the same plane as the device coming out your scope so you can see the entirety of the device in your ultrasound image and that's why you must use a linear scope if you're doing therapeutic EUS. So as I mentioned, you can use a radial EUS scope for staging of esophageal cancer and here you can see one in the esophagus and this cancer was staged as T1 or very early stage esophageal cancer whereas we would use a linear EUS scope if we wanted to sample a target tissue. In this case is a lymph node near the aorta which would really not be accessible any other way than for the endoscopist to visualize the lymph node here on endoscopic ultrasound and then direct the needle into that lymph node and sample it and using aspiration techniques, placing a specimen on a slide and having our pathologist confirm whether or not there's cancer or not. So that's a brief tour of all of the devices. It's a very beginning of what you'll learn and hopefully you'll get a chance to get your hands on some of these instruments when you're in the bio skills session later today. Any questions about devices or instrumentation we use in endoscopy?

gastroenterology

endoscopy tools

upper GI endoscopes

colonoscopes

biopsy forceps

colonoscopy

endoscopic ultrasound