Okay, I'm going to take you through the diseases of the small intestine. And interestingly, you know, we talked this morning about how—Steve talked this morning about how long the small intestine is. It's a tennis court or football field. We don't know. We can debate about it. And despite the fact that it is so large, it is actually one of the areas of the digestive tract that we as gastroenterologists see diseases less commonly. There's not a lot of patients that come in with small bowel disease, if you exclude the Crohn's disease patients and the irritable bowel syndrome, if you consider that a small intestine disease. But in terms of structural and primary diseases of the small bowel, it's one of the less common disease states that we see. So the four areas that we'll cover as we go through the small bowel include celiac Many of you have probably heard of celiac disease, and we'll get into that in detail. Obscure GI bleeding, meaning GI bleeding that's not in the upper digestive tract that we can see with an EGD scope or in the lower digestive tract with a colonoscope. That's what we mean by obscure. It's somewhere in the middle of those two, namely, mostly in the small intestine. Small bowel obstruction or mechanical blockage of the small intestine is another important disease state that we see and often co-manage with our surgical colleagues. And then mesenteric ischemias, the word ischemia means lack of blood flow or insufficient blood flow. So any disease state that impairs the blood flow to the small intestine or the mesenteric circulation really refers to the blood supply to the whole digestive tract. Okay, what about celiac sprue? You may have seen that there is a lot of lay press and a lot of marketing of gluten-free products in the grocery stores, online. And that's because there are some patients that are extremely sensitive to gluten. And those patients may have the disease called celiac sprue. It is an autoimmune disease where the immune system is actually attacking the lining of the small intestine. And that immune stimulation or that abnormal attacking of the immune system on the small intestine is driven by gluten. And that gluten is the underlying stimulus. So by removing gluten, we can actually improve the disease. And we'll talk about what is gluten and how to treat it later. There is a genetic predisposition. Patients have a specific genetic makeup that are exposed to gluten, are the ones that can experience celiac disease. But not everybody with that genetic makeup experiences celiac disease. So there's other unknown factors that are at play in the pathogenesis or the etiology of this disease. So what is gluten? Gluten is actually the protein in several grains, including wheat and barley and rye. Those are the most common grains that contain gluten. There are others. But those are the most common. You'll notice on here that corn and rice are not on that list. And so those are typically grains that are safe for people with celiac disease to eat and consume. Gluten is what gives that doughy consistency to bread and other wheat-based products or grain-based products that we consume. But it's also found in many other products, including cosmetic, skin products, in some processed meats or cold cuts. You can actually have small amounts of gluten to give it the thickening consistency. So it may not be obvious that gluten is in a product unless you really research it. And so it can be quite a challenge to completely avoid gluten. By the way, it's important to realize that celiac disease is not very common. Of the people in this room, maybe one person may have celiac disease. But there is a much more common ailment of gluten-sensitive enteropathy or gluten-sensitive digestive symptoms that's not necessarily related to the protein in wheat or other grains, but more related to the carbohydrates. And that's much more common. Probably 5 to 10 of you in this room will suffer from gluten sensitivity, not from celiac disease. So it's important to make that distinction. So patients with celiac disease will have a broad range of symptoms, including some that have no symptoms at all. And it may only be by happenstance that it's discovered through physical exam findings or even blood work. And you can see here that anemia, particularly iron deficiency anemia, is a common manifestation. Dr. Carpenter mentioned to you that iron is absorbed primarily in the duodenum. And that's the area of the small intestine that is primarily affected by celiac disease. And so you can't absorb iron normally. You become anemic. It's one of the laboratory abnormalities that people with celiac disease can develop. Many will develop abdominal pain and cramping and diarrhea. And obviously, those are very common symptoms. In fact, very common in patients with what Dr. Ali is going to talk about is irritable bowel syndrome. And as a result, it's recommended that all patients with irritable bowel syndrome be tested for celiac disease because of the potential that that could be driving those symptoms. In the very severe cases, it leads to really gross malabsorption, the inability to absorb, both digest and absorb the nutrients that are important for our nutrition. And that can lead to weight loss in adults and growth failure in children for our pediatric colleagues. And then other metabolic consequences, including bone disease because you're not absorbing adequate amounts of vitamin D and calcium, and other nutritional deficiencies, including micronutrient deficiencies. We diagnose celiac disease by a combination, typically, of blood tests. You can see that there's three main blood tests that can be used. They're all very accurate and very good at detecting celiac disease. However, they're not perfect. And really, the gold standard of diagnosing celiac disease is an endoscopic biopsy of the small intestine. And this is what endoscopy would look like in patients with various degrees or manifestation of celiac disease. Again, we're in the upper part of the small intestine, or the duodenum, doing an EGD, or an esophagogastroduodenoscopy. Here you can see in the distance, the duodenal folds, or the valvulae conivente that we often refer to, actually appear relatively preserved. You see these discrete rings, but further upstream in this small bowel, those folds are flattened. And that's often an early sign, or one of the signs, I should say, of celiac disease. We often will also see these scalloping, or these little divots, in the small bowel mucosa that can be an early sign. And then finally, you can also see a nodularity to the small bowel. But it's important to realize that about 15 to 20% of people with celiac disease will have a normal-appearing small intestine. It appears normal to the naked eye, to me as an endoscopist. So if you suspect it, you should take biopsies of the small bowel so our pathologists can look under the microscope to see if there are the typical histologic findings of celiac disease. Now, how do we treat it? Simple. Just take away the gluten. In the vast majority of patients with celiac disease, you take away these yummy breads and the disease goes away. Unfortunately, as I mentioned, it's really hard to do that. And you have to be almost completely off of gluten, for even small amounts of gluten can trigger the immunologic response that causes that damage. So it is really important to be very strict in avoiding all gluten. We're gonna move on to the next small bowel disease, and that is obscure GI bleeding, meaning, again, it's not within the reach of an upper or lower endoscope, a standard upper or lower endoscope. And it really is about 5% to 10% of all GI bleeding events. And I want you to remember that 10% number, 5% to 10% of all GI bleeding events occur in the small bowel, meaning it's obscure. It's not within the reach of an upper or lower endoscope. That can be occult, meaning there's no obvious blood that you can see in the stool. And that's usually a chronic GI bleeding event. Or it can be overt. In other words, there's gross evidence of bleeding, either black stools or blood in the stools, in patients with more brisk small intestine bleeding. There are a lot of different causes of small intestine bleeding, including ulcers. Duodenal ulcers and gastric ulcers are some of the more common causes of upper GI bleeding. But these ulcers can be also present further down in the small intestine, and those could be due to either Crohn's disease, sometimes taking nonsteroidal anti-inflammatory drugs can also cause small bowel ulcers, and that can bleed. This may be one here. In elderly individuals, angioectasia, or these degenerative tangles of blood vessels in the lining of the small bowel, are very common in elderly individuals. And those can also bleed, particularly if they're on anticoagulant agents. We can also have small bowel polyps or tumors that bleed in the small bowel. And a rare condition, which is called Dullafoy's lesion, is just a special type of vascular malformation, which is an artery. And here you can see an artery spurting blood across the lumen. Meckel's diverticulum would be something that would be much more common in the pediatric population. It's a congenital anomaly of the very distal small bowel that can also be the source of bleeding. So how do we evaluate obscure GI bleeding in the small bowel? Well, we're going to typically repeat both an upper and lower endoscopy to make sure it's not something that's within the reach of our typical instruments. And then if we don't find that, we will typically go on to what's called a capsule endoscopy. And a capsule endoscopy is, as the name implies, a pill-like structure that has a camera in it. It's disposable. We don't recapture them and reuse them in patients. It is swallowed, and it takes anywhere from four to 10 pictures a second as it's tumbling through the small bowel. Those are all wirelessly transmitted to a digital capture device that the patient is wearing. And then that digital information is downloaded to a workstation for a gastroenterologist like me or any of my colleagues to review those images and look for the source. And here you'll see a video of what a capsule endoscopy looks like. It is bouncing around, again, taking pictures, multiple pictures a second. If you get close, you can see the villi of the small bowel here. And here you can see an ulcer. You see the ulcer? As it pops in and out of this area, there's a slightly ulcerated stricture that shows up within the image. There it is right there for you. It's kind of a strictured area, and it's got an ulcer in it. So that could have been the source of bleeding in that patient. We can detect many different things, including whether or not there's active bleeding will show up, and that's very helpful, especially if somebody has overt, obscure GI bleeding. We can detect small bowel tumors or growths in the small bowel. We can see those angioectasias that I mentioned earlier, and also tinier small bowel – small ulcers or bigger ulcers in the small intestine, which may be the culprits. Now we don't always – we can use this for investigating other small bowel diseases, including Crohn's disease, as well as GI bleeding. The most common reason we're doing capsule endoscopy is to investigate GI bleeding, which we think is coming from the small bowel. Now the disadvantages of a capsule endoscopy is that we're not – we can't control what's happening in real time. We're just recording what the images are. We can't take biopsies. We can't intervene. We can't stop bleeding if we see it. It often takes a long time to go through hours of images. There are some – there is some software and some early artificial intelligence work that's looking at how to make that a much more efficient process. And there is a slight risk of retaining the capsule where the capsule gets stuck. You saw that slight stricture in the small bowel. We can imagine there may be some patients, and that's about upwards of 1 percent, where the capsule won't pass and it gets stuck. And there are some safety maneuvers or tests you can do beforehand to help limit the risk of that. Unfortunately, it requires either surgery or a special endoscope to go in and retrieve that capsule. Okay, so what if after repeating the upper and a capsule endoscopy, often what we then do if – especially if the capsule endoscopy identifies a source of the bleeding is move on to a deep endoscopy, which is a device-assisted endoscope. And those are special devices that not all gastroenterologists use. We often have a very specialized team of gastroenterologists that use these devices. And they're designed to go deep in the small intestine, both forward or antigrade from the mouth and also retrograde after you pass the colon up through the distal part of the small bowel. It really is designed to pleat, and you'll see a cartoon of that in a minute. The small bowel folds and really retract the small bowel in an accordion-like fashion back onto the endoscope. So you can have your tip or the optic portion and the visualizing portion of the scope advance further. It can be done both antigrade, which is through the mouth, and retrograde through the rectum so that you can more effectively and reliably hopefully visualize the entirety of the small bowel. So this is what a deep endoscopy would look like. We have the endoscope, which is here in the tip, and this blue part is an overtube that has a balloon on it. This is what we call a double-balloon endoscope, and there's also a single balloon that can be used. So after it's positioned in the upper digestive tract like this, the endoscopist would advance the endoscope as far as it can go, but eventually it won't go any farther because it just keeps looping. At that point, they would inflate the balloon on the tip of that endoscope, deflate the balloon on the overtube, and then advance the overtube over the endoscope and catch up to it, so to speak. You would then pull both balloons, pull the entire amount of small bowel backwards, and you can see it's accordioning back onto or telescoping back onto the balloon and endoscope, and then you would repeat that process. Once it gets straight like that, you take the balloon down off the endoscope and you keep going forward, and you repeat that over and over and over again to get further and further down the small intestine. Once we get down there, we can do a lot of different treatments. Unlike capsule endoscopy, we can actually cauterize bleeding blood vessels or biopsy masses or other interventions. If we don't, the other tool that we have in evaluating obscured GI bleeding is radiologic tests. This is a nuclear medicine scan where we take a sample of the patient's blood. We label it, or not us, but our nuclear medicine docs label it with a radionucleotide agent and then put the patient back under a gamma camera, and you can inject that blood back into them, and you can see if the blood is accumulating in the GI tract, and here's a sign of blood extravasating, and that's a sign they're actively bleeding. Our radiology colleagues can then go and perform an angiography, which is similar to what's done with cardiac catheterization to image the coronary arteries. They can image all of the vasculature in the arteries of the intestine, and if they see, in this case, you can see extravasation of contrast from a terminal branch, they can then advance some coils or devices into that artery to clot it off and stop the bleeding. So the treatment of the bleeding really depends on the severity. Sometimes if it's chronic and low-grade, it just needs iron supplementation. Many times it does require blood transfusions, and then if it's really acute, we would have severe bleeding, we'd have to do endoscopic hemostasis, the radiographic interventions, including angiography, and very occasionally surgery. That's much less common these days. Okay, the last thing we're going to talk about is small bowel obstruction, and this is a mechanical blockage of the small bowel where the intestine becomes completely blocked. It does prevent normal digestion. It's a medical emergency, so the patients really have to be seen immediately. It presents with abdominal pain, distension, nausea, and vomiting. Things aren't able to go through, so if they don't go through, they start coming back up, and our digestive tract is making upwards of eight liters of secretions every day, and so if it can't go down, it does come up. The causes include adhesions or scar tissue, and these adhesions are often the results of previous surgeries. That's probably the most common cause of small bowel blockage. Hernias, which are blind little pouches where the intestine can get trapped in, and that entrapment can lead to a blockage. A tumor can cause a blockage in the small bowel, obviously. This deception is when a part of the small bowel accordions on itself, and that can lead to a mechanical blockage. That's rare, and then strictures are another common cause of small bowel blockage. We will typically see these. This is what a radiograph of a stricture looks like, and that's an endoscopy of a stricture. We will typically see these in patients with Crohn's disease or have had previous surgeries and many other causes. We diagnose a small bowel obstruction based on x-rays, and here you can see dilated loops of small bowel, often with fluid in it because things can't get through. It just accumulates in that small bowel, and a CAT scan is often necessary to help further understand where the blockage is in the small bowel and help determine what's going to be the best sequence of treatment. The treatment is usually decompressing the upper digestive tract by placing a nasogastric tube and suctioning all the contents out so the patient doesn't vomit. They're going to be correction of electrolytes because they often do have electrolyte abnormalities and replacing their IV fluid. Ultimately, if that small bowel blockage does not improve, they will need surgery to correct or remove the blocked segment of intestine. The very last thing is just the blood flow issue to the mesenteric circulation. If it's acutely blocked, that can lead to what we call mesenteric ischemia. That is severe pain, often with shock and abdominal pain, and that's a surgical emergency. These patients often have abdominal pain that's out of proportion to the severity of their physical exam findings, and you can think of it as the patient is having an MI of their digestive tract. A blood clot is acutely blocking the arterial blood flow to the intestine and needs to be dealt with emergently. Chronic mesenteric ischemia is more due to chronic blockages of the blood flow, so it's the angina. The patient that overexerts themselves, they'll have chest pain, and then it relieves when they rest. Well, in chronic mesenteric ischemia, that pain often occurs after they eat because the blood flow or the demand of blood flow to the intestine is high after we eat, and they will often have abdominal pain and weight loss and a fear of eating. The treatment of these conditions really is dependent on the source and the cause. We diagnose this with imaging. We can see here a blood clot blocking the blood vessel, and there's a number of abdominal imaging tests that we can use. The treatment will either be interventional stenting, much like they do with coronary stenting in the case of a chronic blockage, and very occasionally surgery is necessary, especially if there's dead bowel or if the intestine has essentially necrosed as a result of the blockage in the blood flow. So I'm going to stop there. We'll now move on to our next topic, which is Dr. Ali, who is going to be giving us an overview of IBD and IBS. To see? Thank you.

small intestine diseases

celiac disease

obscure GI bleeding

small bowel obstruction

mesenteric ischemia

gluten intake