So, we're going to talk about the more diseases that affect the small intestine. You already saw the anatomy earlier. Okay, so as a reminder, we have the esophagus going to the stomach, which we just reviewed, and now we're going to focus on the small intestine in the middle before the large bowel. So, we're going to talk about a couple of diseases. We're going to focus on celiac disease, which was mentioned earlier. Something called obscure GI bleeding, so lots of GI bleeding can occur anywhere in the GI tract, but we're going to focus on what affects maybe the small intestine more. Bowel obstruction, specifically small bowel obstruction, and something called mesenteric ischemia looking at the vasculature. So, celiac disease is under the umbrella of autoimmune inflammatory condition of the small intestine, genetic predispositions, you'll have a family history. This is related to the exposure of gluten, which causes immune system to inappropriately signal damage towards the small intestine. We don't fully understand, you know, what leads to the formation of patients developing outside of the genetics that can be passed down, but what leads to that gene mutation, you know, more to come, we don't know yet. But we talked about the genetic predisposition. So, what is gluten? I mean, we live in 2024, so everybody's pretty familiar with this, and even if you don't have celiac disease, we're concerned about gluten. So, it's a protein found in wheat, barley, and rye, and it gives that doughy texture to your dough. It's found not just in food, which not everybody understands, so this is important. It's in cosmetics, it's in hair products, skin products, so anything that you're putting on your body can also give you that exposure. Symptoms of celiac disease, it's a spectrum. So, there can be patients who are just asymptomatic, nothing, I'm coming in because my primary care doctor did my annual labs, and I'm found to have iron deficiency, like we talked about, so our vitamin, you know, deficiencies that are signaling something is going on in the GI tract, so they come see us. So, they may not have any other symptoms. Others can have vague symptoms associated with some of their laboratory abnormalities, especially anemia, so they can feel fatigued, tired, just can't get, you know, sleep, restless leg, other things like that. And then in the more symptomatic patients, you can have abdominal pain, cramping, diarrhea, and then these can continue to be more significant with malabsorption of nutrients and vitamins, and then you can lead to weight loss. In younger children, you can have even growth failures and retardation, and then bone density loss with the lack of vitamin D, you can have osteoporosis as well at a younger age. So, how do we diagnose celiac disease? So, mostly a serological test, but the gold standard is an upper endoscopy with duodenal or small bowel biopsies. So, the blood test is pretty easy. It's less invasive than an endoscope, so if you have a high index of suspicion, you know, somebody's coming in with symptoms, iron deficiency, you can do tissue transglutaminase antibody, which is an IgA antibody that you can test for through the blood test, and that's pretty sensitive and specific for celiac, about 95 to 98 percent sensitivity, so it's a pretty good test. So, if it's positive, you know, you can go further with doing just a gluten-free diet or follow it up with an endoscopy to see severity, but if it's negative, it has a pretty good, you know, ruling out also. There are other panels of testing for celiac disease, deaminated gliadin peptide and endomycete antibodies, which are sometimes available on panel testing, but you can also just go to the most sensitive test, which is a tissue transglutaminase. The other tests don't have as good of a sensitivity, so they can be falsely positive, can lead to further testing, so I typically, in my practice, just go to the targeted test. So an upper endoscopy, what does celiac disease look like if we did this? So on your far left, you'll see kind of like flattening of the villi, like Dr. Yun talked about, the shaggy carpet in the small bowel, that's kind of a fun thing when you start doing scopes, our fellows, our medical students love seeing that. So it's very different than the gastric lining and the colonic lining, so small bowel will have that finger-like villi, shaggy carpet, but with chronic inflammation, it'll get like stubbed or nubs, you know, if you have on a hand, and so it'll look very flat. You can also have scalloping, which is like, you know, kind of these bumps with these grooves, so that's what that is showing right here, the scalloped appearance, and then you can also have nodularity, where, you know, lumpy bumpy appearance. Just by having these types of imaging on endoscopy, it is not diagnostic for celiac disease, other diseases like Crohn's disease, other inflammatory conditions, infections can also cause these types of findings, so, you know, histological diagnosis is very important. So treatment, celiac disease doesn't have like fancy drugs, it's truly avoidance of gluten, so this is where we go into a gluten-free diet, and it's strict avoidance. In our practice, we typically also, just not just educating them, but we also partner them up with, the patients up with a dietician who can explore their diet better, educate what gluten is, where they may be unintentionally getting gluten, there's something called cross-contamination. If you're going to a restaurant that's cooking like bread in one, using wheat products in one part of their kitchen, but then cooking something else in that zone where you have, you know, the dust of that, you know, a flour in that zone, you could get some cross-contamination and the patient could inadvertently get gluten. So those things can, you know, impede progress for our patients, so having a dietician and us follow along with some objective laboratory, you know, endoscopic findings are helpful to manage their treatment. Okay, so moving on to topic number two, which is obscure gastrointestinal bleeding. So typically, this is where we've done an endoscopy, an upper scope, or a colonoscopy, and we really haven't found what's causing bleeding. So it can come in two kind of flavors. You can have obscure occult bleeding, where we have kind of markers of blood loss, like anemia, but we're not maybe capturing the, you know, black stools or the bright red blood visually. And then you have overt, obscure overt bleeding, where you're seeing the black stools or the bright red blood coming out, but, you know, you haven't found the source on the upper or the lower scopes. So this accounts for about 10% of gastrointestinal bleeding, and, you know, this is very challenging, as you can imagine. So typically, when you're looking at obscure GI bleeding, about 75% of those patients, the lesion or the cause of bleeding is in the small intestine, though you can see still obscure GI bleeding from a missed, you know, small little blood vessel that you couldn't see, because sometimes we're looking at millimeters of, you know, blood vessels that we can easily miss on upper and lower exams, and that's 25%, so sometimes you have to repeat these studies, you know, over and over to finally capture, you know, what's the source. So some of the causes of obscure GI bleeding can include inflammation anywhere in the small intestine, such as Crohn's disease. You can see ulcers in the small intestine. Those anti-inflammatory medicines, like the ibuprofen, it's typically targeting your, you know, duodenum and your stomach, like Dr. Gonsalves talked about, but it can really cause ulceration anywhere in the GI tract, so the small bowel is still, you know, the rest of the small bowel is still at risk. And there, of course, can be infectious and other causes of ulcers throughout the small bowel. So we talked about dulafoil, which is this small little artery that dives out from the semicostal area and then into the epithelium and shoots. So this is, like, very, you know, tightening our anal sphincter when we see it on endoscopy. We're focused, we're trying to, you know, close this sporting blood vessel, but it can also be difficult to find, because sometimes by the time we do the endoscopy, it's dived down, it's in its closed state, so we're not visualizing it. So these can be challenging. So sometimes it takes repeated exams to find it and to close that artery. Other times we can see these small vascular lesions called angioictasias. They can occur anywhere in the GI tract. Sometimes they're affiliated with other diseases, but, you know, they can be very small. They can hide between the folds of the intestinal tract. So again, detection can be hard. So there are millimeters sometimes in size, and they don't have to be actively bleeding. So you have to have a high index of suspicion looking for them. And then you can have other anatomical changes like Meckel's diverticulum, so you can form diverticulum anywhere in the GI tract. We talked about zankers in the esophagus. There can be diverticular disease in the colon, but in the end of the small intestine called the ileum, you can have this specific diverticulum called Meckel's, and it can also cause bleeding from this area with the artery sticking out. And then small bowel tumors can, of course, occur, malignant or benign. So how do we go about, you know, locating these things? So we've done an upper endoscopy sometimes. We repeat the upper endoscopy or the colonoscopy. And then we use other sources to look at the GI tract. As Dr. Yoon talked about earlier, the GI tract in the small intestine is very long. When you kind of stretch it out from the squished components of your abdomen, it's a very long surface area and distance to cover. So our standard upper endoscopes and colonoscopy going retrograde do not, you know, cover the entirety of your small intestine. So sometimes we use a device called capsule endoscopy, which is basically a big pill, like a multivitamin-sized pill, rounded, you know, soft edges with a camera built into it. And that can look at the rest of the small intestine and give us some data. So it's a disposable device, which is nice, and the patient doesn't have to fish it out from the toilet. So, you know, none of that. But it has a—it's taking, like, a million pictures a second, essentially, and it becomes a movie. In our institute, we have the standard eight-hour pill camera, but there's also a 12-hour one that we tend to use in some of our motility patients, our sedentary patients, because you don't want that pill camera to stop recording halfway through your GI tract. So sometimes for various reasons, you know, you want the longer timeline. So the patient will swallow it. Sometimes we will place it if there's other disorders, where there's obstruction or other reasons where the pill camera or motility issues cannot get into the small intestine orally in a timely manner. So then we'll do an upper endoscope, and we have attachment devices to our scope that attach the pill camera, and we drop it into the small intestine to start recording there. Once it starts recording, there is a receiver device that's wirelessly recording all of that data from the pill camera as it's transiting through, and it's stored on a device that will be turned back from the patient back to our lab, and then we download those images, and then the doctor has to run through that eight- to 12-hour recording. So it can take some time, but the more you read it, you can get pretty fast at picking up and reading these things. So then we review, and we see if we can find any abnormalities. And you saw the video here playing. So things you can see on pill camera, you can see active bleeding. So you can see blood, whether it's coffee grounds, dark or bright red. You can see tumors or bulges or growths in the small bowel. You can see these vascular ectasias like the angioectasias here. As you can see, they're very, you know, small, and if you have bile or stool obscuring your view, you can miss these very easily. And then, of course, we can see ulcerations, these breaks in the lining right here. So pros and cons, right? So we can see the entirety of the small bowel, which is great. However, it still requires a laxative clean-out, just like a colonoscopy. So that can be difficult for some of our patients who've already had multiple clean-outs for a colonoscopy maybe the day before, a couple days before, as we're still searching for the source of their bleeding. And also, it only examines the small intestine. It's not designed to look at the esophagus, the stomach, and the colon. So you're limited to the data from the small bowel. It cannot take biopsy. It cannot intervene. So yes, it identifies a cause, but now we have to be able to reach and figure out what to do about it therapeutically. So long reading times, it's a long movie. So of course, you know, take some time out of the physician to read it and to be able to find the abnormality. And of course, there are some mechanical issues. So if you have a patient who has a motility disorder, it cannot go through all the way. That can delay the reading and getting all the data in the recording. Second, it can also get stuck in the small intestine. So if you don't know that there's a tumor or a growth that's occluding the luminal track, it has a fixed diameter and body. So the pill camera is not malleable to go around something. It may get stuck. But sometimes that's in itself a diagnostic tool because now, hey, we found where the pill camera is stuck. So we may have to go in surgically or endoscopically to retrieve that camera and also to figure out what's sitting there. Common things to see in our surgical patients who've had, you know, small bowel resections for various reasons, strictures, narrowings, like inflammatory bowel conditions, tumors. So you have to be very mindful. We do have a dissolvable barium, kind of same shape, size, called a patency capsule that we, if we have a concern that this patient may not be a good candidate, we typically, you know, kind of test the waters with that patency capsule where they would swallow. You do some x-rays and see, did that, you know, that temporary capsule get stuck? If it did, you know, we may not want to consider it an actual pill camera. The good thing is that a patency capsule will disintegrate. It's just barium. So it's not going to harm the patient. So you can do those ways to figure out if this is a good patient for a pill camera. Okay. Other options are deep enteroscopy. So we do have longer, what we call small bowel scopes or enteroscopes, where we can get deeper into the small intestine beyond a standard upper endoscope or a colonoscope from below. And these come in a couple of different ways. So there's something called balloon-assisted enteroscopy, and there's two, but it's a spiral rotational enteroscopies. The balloons, there's two types. There's double balloons, exactly what the name says. There's two balloons, and then there's a single balloon. So depending on the institute, these are not available at most community centers, and you have to have a physician who's comfortable operating them or experienced in that. These are very long cases also to require more block time in your endoscopy schedule, longer anesthesia time to go searching. So there's many factors why some physicians adopt these types of techniques and others don't. So typically, these are mostly in referral centers that you'll see in larger hospitals or where there's a large volume of these types of difficult bleeding where the standard gastroenterologist in the community may start the workup, and they feel like, OK, I think this patient now needs an enteroscopy. They'll refer to a tertiary care center for that. So the endoscope is advanced into the small intestine by inflating and deflating the balloon, that's how that works, to basically pleat. So it's a push and pull technique. So it's such a long length, you have to shorten it, but to still see the surface area, so pleating over that length of that camera, and the balloon helps to kind of go there fixed and then pleat over that and then deflate, get some more and pleat over that. I'll show a cartoon a little bit more. So the double balloon is a little bit more effective than single balloon. Can evaluate the entirety of the small mouth, so you can actually reach the ileum and intubate the terminal ileum too, which is very helpful. You can go anterograde, which is through the mouth, and then retrograde through the rectum, but you gotta get through the colon into the terminal ileocecal valve and into the terminal ileum. That can be fraught with a lot of challenges. And if the patient has a lot of scar tissue adhesions, that can also affect how we can pleat safely. So this is a cartoon of a double balloon. So a balloon goes out there, and then we put the second balloon, and you pleat, you shorten that length, and then you keep repeating this as you're inspecting. Okay. So then there's also rotational enteroscopy and just another type of tool. And basically, again, the endoscope is advanced through the mouth into the small intestine, and there's a spiral-shaped overtube over your enteroscope. And it's a rotational kind of clockwise and counterclockwise maneuver instead of a balloon to, again, pleat the bowel and move things forward in a spiral manner this time around. So this is kind of like a corkscrew in a way, where you can see it advancing. Sometimes we do have to use, or frequently we have to use x-ray guidance when we're doing these types of deep enteroscopies to kind of know what's going on. And it helps with a lot of looping. As you can imagine, these are very floppy, long tubes, so things can just kind of get like a pretzel twist, and it can be difficult and lead to complications like perforation risks and et cetera. So we will sometimes use fluoroscopy to assist us in looking at our loops, and where we're located from the outside. When we find a lesion, for example, if it's like a bleeding vessel, ulcer, or like an angioectasia, we can use thermal energy to cauterize. We can use clips to close the defect of the artery. And then, of course, if we see tumors or anything else abnormal, we can take biopsies. So that's the deep enteroscopy we talked about. And then there's radiological, which is a very important part of the deep enteroscopy. Sources of localizing where the GI bleed might be coming from. Again, this is kind of a chase of figuring out where is it coming from in these types of tools. So radiology can also assist us when we've done everything we can, or we don't have a resource like enteroscopy at our institute. So sometimes we target from a tagged RBC scan. So basically, we radio isotope label the red blood cells through an IV, and then the patient is then sent into a nuclear medicine scan. And we try to see where the blood may be extravasating. So you have to have activity of bleed, right? And this is where these tests can be, you can do them, you can have access to them, but actually to be useful where they're diagnosing something can be very difficult. So in the early, you know, you see the blood where it's supposed to be in the aorta, iliac, and the femoral arteries. And then you see this like delay of blush where it might be leaking. Again, it doesn't give us anatomy, it just tells us, okay, it's in the right lower quadrant somewhere in there. So it could be small bowel, it could be the beginning of the colon, and that's up to our judgment. So it could be very difficult then. A little bit better is an angiography or CT angiography is also available at your institute. So you have to have a little bit of a faster bleed to use a CT scan where it's a tag, you can have a slightly slower ooze that you can detect. But again, the activity of bleeding must be there. This involves a lot of dye because you're putting a lot of contrast through the patient's veins to get into the artery and radiation, right? We're putting them under X-ray or CT to see where there may be an extravasation of blood. But the good news is this can also be a stepping stool for intervention. So this is a little bit preferred technique if we can have that available, because if you see a local localization, either you can go in with your camera and figure out if that's the right step or you can have interventional radiologists at your institute do something called embolization or reach that through the arterial track and put a coil and close that bleeding source. And this is what they're showing with that coiling. They found the blush, they found the source, they went in there and cut off the blood supply to that bleeding source. So it really depends on what is the cause of your bleeding to require the type of intervention. So sometimes it's just a very slow ooze, patient's not very symptomatic, so you can just supplement iron while you're trying to figure out what's going on just to support them through it. Or if it's a chronic condition that continues to ooze and bleed, you can't keep going in there endoscopically every other week. So sometimes we just give IV iron infusions or iron supplementation blood transfusion to kind of when they get low enough to kind of support them. Of course, endoscopic hemostasis would be great, but it's not always the right option from every condition. And then radiologically. And last but not least, we do revert to surgery. If we can identify what we can't reach or are not able to stop the bleeding, then surgery is always the last resort. At our institute, we also use surgery as one of the kind of adjunct therapies to open up and do an enterotomy where they can do surgical assisted enteroscopy. So we try not to resect the bowel, but maybe they can help us pleat and get to the location, and then we can do thermal energy or some other intervention during the surgery, and then they can just close the patient out. So various ways you can approach that. So moving on to the other topic, small bowel obstruction. Bowel obstruction can occur in many places depending on whether it's mechanical or functional. We kind of heard about the gastric outlet obstruction earlier with Dr. Gonsalves. So now in the small intestine, same kind of options can happen. Again, whatever the obstruction is basically preventing things from moving forward. So we're having backup. So lots of symptoms can occur that are similar to stomach obstruction. And this is sometimes considered emergencies because we worry about aspiration, dehydration, and of course, perforation. So a wide variety of symptoms can occur. Abdominal pain, distension, nausea, vomiting, because things are backing up and going up this way instead of moving forward. And of course, constipation too, because we're not able to defecate. Many causes of bowel obstruction, but mechanically, one of the most common is scar tissue adhesions. If a patient has had prior surgeries, very common prior inflammation in that area, it can lead to adhesions and various reasons. So hernias are another anatomical cause. So depending on the sac of the defect in the abdominal muscle, where the bowels are kind of protruding out, some hernias are very large. So bowels can just kind of free float in and out. Patients never have any problems, but others can have kind of a smaller neck where the bowel can go into, excuse me, can go into that sac and get stuck and trapped. And then that can lead to a mechanical obstruction. And of course, can cause more strangulation and ischemia of the bowel. And that can lead to perforation too in the future if it's not caught in a timely manner. Growth, any kind of small bowel tumors can be obviously a source of obstruction to the movement forward, can require surgical resection of that. So just a summary of those. Lastly, there's something called intussusception. This is where the small intestine can telescope within itself to cause a mechanical obstruction. It can be transient where it's coming and going. We can see this in various conditions. It's also common in gastric bypass and other kind of surgical states. So you have to kind of catch it in the moment. It can be hard to detect on CT imaging. And then inflammatory conditions such as strictures where we can have a narrowing in the caliber of the lumen. So Crohn's disease commonly, sometimes radiation, surgical strictures where things have scarred down from a healing perspective, various things can cause strictures which can impede the flow forward. And then lastly, b-zores. So there can be motility issues, lots of reasons where patients are ingesting odd things and where it can accumulate over time and this food b-zore can accumulate and it can be medication related to, and it just creates this mechanical accumulation obstruction where you have to kind of empty that out depending. Commonly seen in the stomach with gastroparesis, but it can also occur in the small intestine. So other diagnostic tools that we have are x-rays. So if we are complaining abdominal pain, sometimes we can see early signs of obstruction where things are not moving forward, but you can see this dilation of like air fluid level because things are not moving forward. You have swallowed air, an air that we have in the luminal track kind of layer above the liquid that's accumulating. We still make digestive enzymes and juices despite things not moving forward. So that's kind of, it's like a Coke bottle with like, you know, you can have the succussion like swishing where if you made it into like a horizontal position, you can see the air fluid level. So you can see that on x-ray as well as cross-sectional imaging. So a CT scan is a little bit better where you can identify the dilation, but you can see the transition point where things are upstream dilated because there's a fixed abnormality at one point and below that it's like decompressed and deflated. So you can identify where the problem might be and what it could be. Is it a tumor, a mass, inflammation, stricture, et cetera? So it can help us better. So acutely, we sometimes decompress the patients because they're just throwing up and throwing up and feel very uncomfortable. So you don't want them to keep aspirating. We put a nasogastric tube to put suction all the gastric contents and juices that have accumulated or backed up. And then we wanna resuscitate them because hydration is key. And then treatment really depends on what is the cause. So if it's surgery, if it's something that we can do less invasive like endoscopic removal, we may go in there. But commonly, like we're talking about adhesions, they go in there. They try to lice the adhesions of scar tissue that's trapping the bowel. And sometimes we can't always save the bowel depending on what it is. So it needs to be resected and then put back together. Last topic I wanna talk about is mesenteric ischemia. So this is inflammation and injury to the small intestine lining due to inadequate blood supply. So we have a very complex blood supply in the abdomen. Usually the gut is really blessed because we have multiple backup supplies. So usually, if somebody has a heart attack, there's a big clot or a plaque that's obstructing the flow into that part of the heart, you get a heart attack. However, in the gut, if there's an obstruction, usually there's collateral flow so we can be kind of protected. But sometimes if the lesion or the cause of injury is devastating enough, it can really cause a lot of damage. So mesenteric ischemia comes in a couple of flavors. It's acute mesenteric ischemia and chronic, depending on what's causing it. So for example, acute, we have like a blood clot that showered and dislodged from somewhere else and formed, or somebody who's in a hypercoagulable state can form blood clots, and they can have acute abdominal pain, tenderness. Usually it's out of proportion to the exam where they're really in pain, but the belly feels soft. You're kind of like, are you sure something is wrong? So these are some of the things that you want to think about but they'll also have shocks or sometimes hemodynamic instability. Chronic, it's more like chronic slow obstruction over time. So think about plaque, like atherosclerosis. So just because we have coronary artery plaque doesn't mean we can't get the same type of process in our arteries of our gut and our abdomen. So you'll typically see patients have postprandial abdominal pain, meaning after eating, they notice the symptoms more. They'll have weight loss because they'll start to avoid eating because of the pain. They'll limit themselves and they'll have fear of eating. So you have to kind of tease out the differences. And that's more chronic. So this is showing an acute mesenteric ischemia example where you have a blockage of the superior mesenteric artery. And that's shown over here with that clot right there, sitting there. So because that clot can be completely occluding flow, you can lose the blood circulation to this part of the bowel and that can get really injured by not getting blood circulation. So it can look purple instead of the nice pink. So sometimes surgeons will call it dusky colored appearance and it can get pretty bad enough to be gangrenous even, which is bad. Chronic mesenteric ischemia is kind of seen more on vascular imaging. So you could use CT arteriograms or like actual angiographies to obtain this. So you have an occlusion or narrowing at at least two of the three mesenteric arteries. We have the celiac branch, the SMA branch, the superior mesenteric artery and the inferior mesenteric artery, the IMA, feeding the GI tract. So two out of three have to really go out to cause significant symptoms. Again, we have a lot of collateral flow so the gut has a backup. So seen in patients with plaque disease, atherosclerotic disease, coronary artery disease. Abdominal pain due to poor blood supply of the small intestine is the cause of your symptoms. So we talked about angiogram. We have CT guided angiogram, MR angiogram as well and Doppler ultrasound. So many modalities to look at the flow of the blood in the artery and what may be going on inside. So this is an angio intervention. So we can go in there with our vascular surgeons who can help us with this. And they go in like a calf and they go into the arterial supply in the main aorta and get into the site, whether it's the superior mesenteric or inferior or celiac and find the source. And sometimes they do angiography live to find the source if not found. And then they can do something called balloon angioplasty, open it up, they can put stents or they may have to resect or do a graft, vascular graft depending on what it is. Okay, any questions? I think we were gonna hold off on the questions. Thank you.

celiac disease

gluten-free diet

small intestine

gastrointestinal bleeding

small bowel obstruction

mesenteric ischemia

diagnosis and treatment