Okay, so I'm going to try to cover the pathology now related to the small intestine. So this is the picture I showed you this morning, just kind of a recap of the organs. So the four things I'm going to be covering is the celiac disease, obscure GI blading, small bowel obstructions, and mesenteric ischemia. So celiac disease, as some of you may know, it's commonly known as the gluten sensitivity the exposure to the gluten has now led to the immune system recognizing it as a foreign thing that it has to generate an immune response. We don't really know what causes the immune system to be so active, but any further exposure of gluten to the small intestine will lead to further damage. So it's an active, just a response of the body. It's an autoimmune condition because the immune system is acting, and there is definitely genetic predisposition, meaning that if none of your family members had it, chances are that you're at a higher risk. So gluten is not only commonly in the wheat, barley, rye, and then now more than ever, we have a lot of gluten-free products, but often what we tell our patient, in addition to dietary restrictions, so the exposure can happen in other forms of, you know, unanimated objects like cosmetics, hair products, and skin products, which may have stuff that contains gluten, and then they could get exposed and could inadvertently lead to a response. So they might be doing a pretty good restriction at home, but these other exposures can lead to symptoms. And when it comes to the symptoms, not all celiac disease patients behave the same way. We see a pretty variable kind of symptom, and then sometimes there's also progression of these symptoms as patients age, sometimes, you know, as the immune system gets a little bit more sort of deflated. As they age, we see that some patients sort of improve as well, so they could range anywhere from being asymptomatic or presenting as growth failure, osteoporosis in a very young kid who wasn't diagnosed and has been exposed to gluten over and over again. The sort of middle portion covers just being fatigued all day, having low iron levels, because the iron, as you may remember, is absorbed from the small intestine, so if the small intestine is damaged, there will be iron deficiency, and then pain, cramping, and diarrhea, other symptoms. So how does one diagnose it? So if, you know, there's a clinical suspicion, if you have a patient who comes in, we usually start off with serological testing. So we tell these patients that, you know, history kind of gives away if it's that severe. Patients often note, or the parents of the kids will note, that whenever they eat a certain thing, they end up having symptoms and not doing well, but if the patients have been consciously avoiding it, then we tell them that, you know, you need to take gluten, and then we'll do the serological testing just to see what the response is. So there are certain antibodies that need to be tested for it. The most common one is the tissue transglutaminase antibody, and then in terms of how our immune system is, we have different types of antibodies still. There's an A, Bs, you know, and so we have to do a specific testing to make sure that the tissue transglutaminase antibody is captured, and even if they have a certain deficiency of a part type of antibody, we still are able to capture it. There are other antibodies that a body develops, like deaminated gliadin peptide, which is also a part of the gluten, and then the endomysel antibody to one of the proteins of the small intestine itself, but both of those are other tests that we could potentially include. The TTG, or the tissue transglutaminase, is the most common and the highly sensitive one. And then once we have a clinical suspicion and, you know, we start off with the serological testing and then we often do end up doing the upper endoscopy, which is the diagnostic. So we take that camera that we have talked about multiple times, go down into the small intestine past the stomach, and then grab some biopsies. These biopsies are then sent off to the pathologist, and then they look and they tell, oh, the small intestine is truly damaged. Sometimes, you know, not always, but sometimes we do see certain pattern on the small intestine, which, if carefully examined, could pick up celiac disease right in the endoscopy examination. So usually we do see a lot of, you know, I showed a picture earlier about all those villi, so that was a healthy small intestine. If you're not seeing that kind of a look, we're seeing more like, you know, the folds are reduced, there's a little bit of scalloping, or we're seeing a little nodularity. So we mark, the endoscopist will usually mark it, what they're seeing, if it's that characteristic to see, you know, characteristic scalloping, then that'll be marked in the endoscopic exam, and then the pathologist takes that into account. So treatment is, obviously, do not, you know, eat gluten or avoid gluten. It's easier said than done. There's a lot of, you know, dietitian help that we require, and a lot of counseling, and obviously, you know, that is, there's currently no other treatment of celiac disease other than gluten exposure, avoiding the gluten exposure. Then comes the exciting part, which is the GI bleeding. Obscure GI bleed is when we really don't know where the bleeding is coming from. We know the patient is bleeding because there is objective evidence of it, but we don't know where the bleeding is coming from. So then it can be further divided into occult, where we're not really seeing the blood coming out, you know, in form of vomiting or in, you know, in from a stool. However, the patient's hemoglobin levels are dropping, and there's no other cause, and our suspicion is really high that this is GI bleed. So it's occult in its nature, and then overt is when patient is symptomatic. In terms of location, most of the obscure GI bleeding would end up being from the small intestine, and it's, you know, it is the longest part of your digestive tract, and it's the most challenging part to evaluate because, you know, as you may have seen or noted in the picture shown so far, that from above, we're able to get to a certain part, which is just the duodenum, not even to the end of the duodenum. And from the bottom, we're going all the way in the colon and then peeking into the small intestine. But really, we're not examining the small intestine, you know, in the regular AGD and the colonoscopy. So the causes, you know, the causes can be in the small intestine, large intestine, both, and then some of them are, you know, in the upper GI tract, meaning in the stomach as well. So Crohn's disease is one of the types of inflammatory bowel disease where there could be ulcerations that could lead to bleeding. Then ulcers, as, you know, Dr. Chang talked about it in the peptic ulcer disease, meaning the ulcers in the stomach, but there could be ulcers in other part of the small intestine or large intestine. We could have dual foil lesions. This was also briefly discussed. So it's a very, you know, it's a blood vessel that's kind of sporting blood. And then angioectasias are just abnormal blood vessels which have a high propensity of bleeding if getting, if they get aggravated. And then diverticulum, Meckle's diverticulum is a small intestine. In diverticulum, usually it's like an outpouching, which we often see in colon, like a lot of people, 8 out of 10 people walking down the street will have outpouchings in the colon. That's how common those diverticuli are. But then you could have some in the small intestine as well. Those are often seen in kids, but adults may have them, and the first presentation could be bleeding as well. And then tumors, you know, none of the GI tract is spared from the tumor. So if there's an ongoing, you know, process, they'll, you know, eventually cause bleeding because of the high vascularity and lead to obscured GI bleeding. So the first, it's actually very challenging to find out or evaluate the obscured GI bleeding. And a lot of times, especially when the patients are on anticoagulation, meaning blood thinners, those become even more challenging because we want to make sure that they don't bleed, you know, and once they're put on it, or we can safely continue the blood thinner. So if the patient gets admitted or is being seen by a doctor, we end up, you know, we first start with an upper endoscopy and a colonoscopy, just because these are the parts easily evaluated. But we all sort of know that if this has been challenging, we know 75% is coming again from the small intestine. So that's the part we're not seeing. So then there are ways. So there's a capsule endoscopy, which is basically a gamma ray in a small capsule that is swallowed just as anybody would take a medicine. So we, you know, prepare them by giving them the similar prep for colonoscopy. So their entire GI tract is clean and good to be looked at. And then they swallow that pill, and the pill just takes pictures all over. Sometimes we have to endoscopically also place the pill in the right place so that, you know, it moves forward and we could get those pictures. So this is the video that we end up getting from the capsule endoscopy. And, you know, once the pill is swallowed, the camera is, there's like a recorder which is placed around as a belt. It's done in an outpatient setting, so patients are kind of, you know, at home doing their own thing, and the pill is moving down. They don't have to get the pill, you know, once it's excreted out. So if you see it in poop, good. You don't have to go retrieve it. Doctors don't want it back. And then the recorder, though, we really want it back because the recorder is, you know, recording those images, and then these images will be looked at. If we see fresh blood somewhere, then that's active bleeding. We know where, you know, this bleeding is coming from. Sometimes we see the angioectasia, so a little bit more prominent blood vessels. Those are not actively spurting, but we know that these could have a higher chance of bleeding. You can see an ulcer, or you could see an active growing tumor. And when you see that in the recorder, we can sort of know how much time has passed. We get an assessment of whether it'd be easier to get to the spot going from above or going from below, and then we do further intervention. So what's missing in this entire study is the intervention part. So you could take pictures, you can tell this is likely the reason for bleeding if we do see something, but we can't do anything with just that camera and the capsule. The problem with the capsule endoscopy is that it's not only that you cannot do any intervention, it doesn't take biopsies. Let's say there was a tumor, we saw the tumor, but it won't take any, you know, anything more than just the pictures. Once the images are given to the physician to read, it's sort of boring to read, look through all the images, and depending on how fast the capsule moves through, you have to like really, you know, be on the lookout, look at, you know, throughout all these pictures, 180 degrees, and make sure that you're not missing tiny lesions, like tiny blood vessels. And then the retention of the capsule is also a problem. So people have had surgeries if they have narrowing, and then certain parts of the digestive tract is narrow just physiologically, and the capsule can get stuck, which will then lead to us going, trying to, you know, fetch that capsule back. So, you know, this boring study can really become very exciting if those things happen. Then there is deep enteroscopy. There are two kinds. One is a balloon-assisted, and one is a tube-assisted. We do do balloon-assisted more commonly than the tube-assisted in certain parts of the world, but rotational enteroscopy or the tube-assisted one is more common, especially in the Asian countries. We have a single balloon and a double balloon. Well, I'll try to kind of, you know, explain through the pictures. It's a little bit harder to explain, but what it essentially is, if you look at the, you know, towards the end, there are two balloons and the double balloon and the single balloon in a, you know, in the SBE. What it does is it's based on the concept of pleating. So what you're doing is you're inserting the scope as far as you can go, and then there's sort of an over-cube, if you will, like, you know, covering that scope the entire time, which has a deflated balloon, and as soon as the balloon inflates, it's going to inflate to the diameter of the small intestine, and then it's going to hold tight that small intestine for you, and then you'll pull it, you'll pleat, you know, cause pleating of the small intestine, and then you'll pull the small intestine towards you. You know, none of you have done endoscopy, and you'll kind of get a grasp of what it feels like later today, but the, you know, the EGD and colonoscopies are actually very easy because none of the areas are moving as fast and rapidly. Small intestine, though, is not forgiving. It just moves and moves and moves, and the more you irritate it, it's actually going to move faster. So, you know, it's, so that's why holding the balloon in a certain position or causing the pleating helps the entroscope eventually to move forward. So that's the benefit, and again, this is therapeutic because you can do a lot of things when you are going in, just as you would do with an endoscopy. So after capsule, we know if there's a thing that we could intervene upon, we usually step up to one of these things. So I kind of tried to explain the pleating of the small intestine, and then we have some pictures. It can be done from above, anagrade, and then below, so retrograde as well. So this is the double balloon endoscopy. You can see the overtube and then inflated balloon, and then the endoscope is moving forward, which also has its own balloon, so kind of holding the small intestine tight. And you can notice the pleating that was there in the small intestine to hold it. Not all endoscopies do it. So I don't do upper balloon endoscopies, but a lot of interventional endoscopies do it. So it might not be available at all the centers, so that's another limitation of this sort of procedure. The rotational endoscopy is sort of like a rotator over the endoscope, which basically rotates and can rotate clockwise, it can rotate counterclockwise. These are disposable elements of the scope, and then basically it does the same thing of pleating the small intestine and to control it, and then you can move forward with that. So those are the two ways of kind of getting to the small intestine. There is your deep endoscopy, which is basically taking the longer scope kind of further down as far as you can go, and if you're able to see what you need to intervene upon, you end up doing the management. So whether it's a bleeding spot or a tumor that needs to be biopsied, whatever it is, we try to get it as far, but all of these are challenging procedures to do, so we really need to know where the bleeding is happening or what's the cause, which is hard to find. Then there's radiologic. So the radiologic assessment usually comes into play when we're really struggling and we don't know. We did capsule and we don't know what's bleeding, or sometimes, depending on the speed, if the bleeding is happening, right? So if the bleed is very fast and if I were to put a contrast in your blood vessel and the blood vessel would leak from a point where the bleeding is happening, then that would be the radiological images will capture that. Or if the other form is tagged RBC where the blood cells itself are tagged, so some blood is taken out, it's then tagged, and then put back into the system, and then when it's going through, then you can initially see how it would normally go through, and then in the later phases, you'll see that where the blood is inappropriately present and shouldn't be there once the blood flow has, you know, when once those RBCs should have moved. So then we know, OK, this is the part that's bleeding. This is usually done when the bleed is a little bit slower in terms of speed, and then it's really fast, or the endoscopist can't get to it, or we did an exam and we couldn't find it, or the patient is decompensating, we end up doing like an angiography where you can see the blood vessels are really branching out and they're really small, so the radiologist tells us that this is probably the area that's bleeding, and then we kind of, what they do after that, once they notice that this area is bleeding, they will specifically go and embolize it so the bleeding stops in that area. So they don't necessarily have to stop the blood flow to the entire intestine, but a small, tiny branch could then be embolized, so it's a pretty specialized procedure as well. So you can see that a little spurt happening on the angiography. So the management, you know, should you see the bleeding with all this assessment that you did, you know, then you can intervene upon it. Sometimes you see or you know what's bleeding. It's frustrating that even if we go in there, it wasn't bleeding or we couldn't find it because of the folds and all sorts of things, or the radiologist couldn't find it. And in those situations, we have to do sort of supportive care with just giving them back the blood or giving them the iron, which is important to make the blood. Then comes small bowel obstruction. It's often, you know, a medical emergency if it's a complete small bowel obstruction. And then what's really happening is that the pipeline is blocked, and it's blocking to the point that the small bowel is getting bigger and bigger and bigger. It's not moving forward, and its usual pathway is to move forward, so it's not able to do that. So as you can imagine, if there is a blockage, you know, the patient's going to be very uncomfortable and often progressively symptoms get worse, so they end up coming with nausea, vomiting, and big abdominal distension. What's causing it? So there are a lot of causes of small bowel obstruction, but one of the more obvious causes is adhesion. So let's say the small intestine, the yellow part that you're seeing between the intestine is just the fat, which is kind of making the small intestine comfortable in that bed. But that in between is the adhesion, which could be because of ongoing inflammation, because of a prior surgery, because of some other issues related to blood supply. So if there's an adhesion, that thing can easily close off or block off the lumen itself and then can lead to small bowel obstruction. So that's one of the causes. And then we have hernia, which is basically your bowel should stay inside. This is a muscle layer, and then the yellow part is just the fat. But if there's a hernia, and then the muscle is sort of weak, then not only the muscle will kind of give away, the bowel will squeeze into and then go and sit in the hernia. Sitting is not a problem, but when it's not able to move or the lumen gets compressed because the hernia also has a neck, then patients often present with an obstruction along with the complications of the hernia. There's a tumor, so there's a big mass blocking the lumen. That's another cause of small bowel obstruction. And then intussusception, meaning that the small intestine decided to fold onto itself. Often because of a mass, a small lymph node, or some other reason, the small intestine kind of folds into itself, and then you can have a problem called intussusception. Strictures are another reason, sort of similar in terms of adhesions, but they're really, really narrowed areas. So you can see in this image that the small intestine, the continuity is not maintained because this area is completely stricture, so the lumen is not paving, so the part above it will end up causing, will be very dilated. Others are basal, this is not as common, but often we do see the collection of, you know, there's a collection which has now caused complete obstruction of the lumen. So it's not a very common cause, but it's one of the causes. When we see such dilation, which will look abnormal to, not just a radiologist, but anyone looking at the x-ray, then we know that this is the problem, and then we sort of start seeing what we call as the air fluid levels, and then we know that this is obstruction. We can step up to doing a CT scan where we can see what we call the transition point, meaning there's an area where above which there's dilation, and below which there's no dilation, so we know that there's a problem at that point, and that's often called or referred to as a transition point, or if there's a stricture or an obvious mass, then the CT scan will sort of give away. Management is, if there is a pipeline blockage, we have to first reduce the pressure. So we have to somehow vent all the secretions that are coming because your stomach is making over a liter of liquid in a day. So everything has to be drained some way, so we put a tube, very uncomfortable procedure for the patients, but we'll have to sort of vent the system. So we put an NG tube, make sure that whatever liquid is coming out, because it is not getting absorbed the normal way. Patients are given bad and bad liquid, the electrolytes are given so that they are stable to undergo an intervention. So let's say if there was a problem, like an adhesion or an area of the small bowel that's affected, so surgery is one way to do it. So where you go, you just cut off that part that is abnormal for one or the other reason, and then kind of sew it back together. And then there's enterotomy, where let's say there is some narrowing or stricture, like if you were to have that inflammation, the surgeons do it, they kind of cut it open and then sew it in a way that that stricture doesn't cause any problem and the continuity is maintained. Next topic is the mesenteric ischemia. So this is the issue with the blood supply to your small intestine. So we kind of discuss if, you know, what would happen if the small intestine continuity is a problem, but this is when if the lumen itself is not getting enough blood supply, what could potentially lead to this? So this is a complex sort of a diagram, but just to make it easy for you all, you have to just know that the small intestine and the large intestine are supplied by the main blood vessels. So your aorta is sort of running in the center, and then it branches into different sort of branches, and then for ease of understanding, there's a mesenteric artery, so there's superior and inferior. The superior part will supply a part of this, you know, most of the small intestine and then a part of your large intestine, and then the inferior mesenteric will supply a later part of your large intestine. So the mesenteric arteries are the major blood supply to your intestines, so if there is a problem with them, then you can have mesenteric ischemia. It could be acute, it could be chronic. So acute is when you have an acute blockage of the entire blood flow, and then there is no blood supply to the digestive tract, to the intestine, and depending on what part is involved, that part, you know, starts, you know, undergoing necrosis, and at the microscopic level, changes start happening, and then patients start becoming very symptomatic very quickly and decompensate very quickly. So this is an emergency. Patients often come in with abdominal pain, or they are really not doing well, sometime in shock, meaning they require to be in the ICU or require medication to maintain their blood pressure. Usually we see a lot of pain, so tenderness is there on examination, chronically when this happens, meaning there is some sort of a blockage which is happening, and it will be more apparent when your small, when your intestine is supposed to work the hardest. So when you eat, your intestine is supposed to work hard, and that's when patients start feeling pain after eating, and because of this pain, they would develop a fear of eating and would start losing weight. So it's kind of, I try to, you know, I think it's analogous to how our symptoms are for the heart, so you could have, you know, chronic sort of symptom, like an angina developing when people exercise, if they have a blockage to the heart, but they could also have an acute heart attack when there's a certain blockage and the entire blood supply is compromised. So this is the diagram you can see, like a small section, which is blocking of the SMA, which is the mesenteric artery, the superior one, and then if there's an acute mesenteric ischemia, it's usually the small intestine is really not doing well, so there's necrosis, there's cyanosis, which is the blueness, the bluish hue, and often these patients are taken to surgery right away. The chronic mesenteric ischemia is when we have the blockage, which is slowly getting worse, and the pain, the abdominal symptoms are slowly happening over time. We will see this is the main aorta kind of running at the back, and then we have branches which are supplying, so if you have blockage in those branches, then patients will often have these symptoms, and this can be easily diagnosed in radiology, so if you see, like, an area of it kind of getting thickened out, then you know that this area is the reason why patients are having symptoms. When we do what we call the angiogram or the CT angiogram, where we're looking at the blood vessel specifically, then you can see that there's a problem in that area. There's a plaque or some sort of a deposition happening inside the lumen of the arteries. In geography, where we put the contrast in the blood vessel, you know, is diagnostic, and then often, if it's an emergency, surgeons have to fix it. When there are more chronic cases, then sometimes vascular surgery can also help out by opening those blood vessels for us. Yeah, that's pretty much what I got for the small bowel pathology.

celiac disease

obscure GI bleeding

small bowel obstruction

mesenteric ischemia

capsule endoscopy

gluten-free diet