I'm a gastroenterologist at Loyola University Medical Center. My specialty is general gastroenterology. I like everything, but I have special interests in treatment of GI infections, the gut microbiome, and microscopic colitis. So we're going to be talking about the small intestine today. And as you heard in the morning, you had a normal physiology of the esophagus, the stomach. And my colleague has talked about the abnormal physiology of the stomach and the esophagus. I'll be talking about the small intestine. So you've seen this diagram ad nauseum today, but the GI system consists of digestive organs, digestive tract. So you talked about the esophagus and the stomach. We're going to talk about the small intestine. So our outline, we're going to talk about celiac spree, obscure GI bleeding, which speaks to the question my colleague tried to answer in terms of where the difficulty in finding bleeding is. We'll talk about small bowel obstruction and mesenteric ischemia. So what is celiac disease? It's an autoimmune disease of the small intestine, and it's caused by an abnormal immune reaction to exposure to gluten. And this causes damage to the lining of the small intestine. We don't know what causes celiac disease, but we believe, and the current opinion is that it's in people who have a genetic predisposition to forming those antibodies against gluten. So what is gluten? It's a protein found in wheat, barley, and rye. It gives dough. It's doughy texture. It's also found in cosmetics, hair products, skin, and skin products. And it's also found in very unique things that you don't otherwise think about that contain gluten. And we'll talk about that some more later on. So how do the symptoms of celiac disease present? It could be asymptomatic, meaning that patients have no symptoms. Patients could present with fatigue, anemia, abdominal pain, cramping, diarrhea, malabsorption, weight loss, growth failure, especially in children, and osteoporosis. So it causes weakening and thinning of the bones. So how do we diagnose celiac disease? It's by a blood test, ideally in patients who have been exposed to gluten. And the reason why is that if you're exposed to gluten, you form enough antibodies for us to detect in that blood test. So the classic blood test we use is something called a tissue transglutaminase antibody. So it's a blood test that checks for antibodies to gluten in the blood. There are other tests that can also be used, something called a DNA-aminated glandin peptide, or testing for the endomycel antibody. In addition to the blood test, we always do confirmatory endoscopy to take small biopsies, to look at it under the microscope, to look for particular features that are diagnostic for celiac disease. So this is an operating endoscopy images of a patient with celiac disease. So that shows reduced folds in the second part of the small intestine, the second part of the duodenum. So you've seen the duodenum earlier on, and you show normally it's characterized by very distinct folds. But in patients with celiac disease, those folds are much reduced. We take biopsies, and this confirms that there's inflammation and loss of the size and length of the villi. This is scallopin, which is also another endoscopy imaging that's suggestive of celiac disease. And the patients can actually have a very nodular appearance of their duodenal ball. So how do we treat celiac disease? Complete avoidance of gluten and anything containing gluten. That's the way we treat celiac disease. So move on next to obscure gastrointestinal bleeding. This is bleeding from the GI tract that persists or occurs without any obvious cause, despite endoscopy. So these are classical patients that present with bleeding, or you suspect may have gastrointestinal bleeding. And you do a bidirectional endoscopy, meaning they have an upper endoscopy and a colonoscopy, and you don't locate a source. Now, these patients can be classified into obscure or occult, meaning that you know or you think they're bleeding, but you don't see it. Or obscure or overt, which means you see them bleeding, but you don't know where. So talking about location, for patients with obscure gastrointestinal bleeding, and we said this is about 10% of all patients with gastrointestinal bleeding, 75% occurs in the small bowel. Another 25% may occur in the upper GI tract or the colon. So these images show etiologies or causes of small bowel bleeding. You can either have Crohn's disease, which we'll talk a little bit more later on, an ulcer in the small bowel. You can have a dulafoil lesion, and this is a subepithelial vessel that bleeds rapidly. You can have a small bowel tumor, which could cause bleeding, a Meckel's diverticulum. Meckel's diverticulum typically contain gastric mucosa, and that's the source of the GI bleeding. They contain ectopic gastric mucosa. And then you can have the angioctasia, which we talked about earlier on. There's a mucosal level of normal blood vessels that bleed from time to time. So how do we evaluate patients with obscure GI bleeding? We repeat the upper endoscopy and colonoscopy. We could do a capsule endoscopy if the repeat upper and lower endoscopy is negative. And capsule endoscopy, this is a disposable miniature camera that's used to visualize the small intestine. The pill is swallowed, and the images are recorded as the pill goes through the intestine. And then the images are downloaded onto a computer and watched like a video. And as you can see, we watch that video, which you can see as the capsule moves through the small intestine, looking around, looking for normal lesions. And this is how we make that diagnosis of small bowel bleeding. So these are images from a capsule study. That shows active bleeding. And we're able to sort of get an estimate of where in the small bowel that bleeding may come from based on the time, what we call the small bowel transit time. And that's from the first gastric image to the first image that you see in the colon. This image shows a small bowel tumor, as you can see there. There's a growth right in the small bowel. In this, you can see an ulcer. In this, that's angiotasis. So these are common causes of small bowel bleeding that can only be diagnosed with a capsule study. So what are the disadvantages of a capsule study? We talked about the advantages in that it can get to parts that the upper endoscopy and the colonoscopy cannot get to. But what are the disadvantages? So it still requires you to take a bowel prep, meaning that you need to take a solution to clean your intestines out for us to be able to visualize the mucosa. And it only examines the small intestine, so we don't have – it doesn't extend into the colon. And we can't take biopsies, meaning that even though you diagnose a small bowel tumor, you'll still need another procedure to go after the tumor to make a tissue diagnosis. And then it takes the long reading time. So capsule studies take about 8 to 12 hours to do, meaning that the patient will have the capsule going through the intestine, so it takes a little longer. And then we have to download that and then watch the video, so to speak, to make the diagnosis. And then there's the risk of retention of the capsule in patients who've had previous bowel surgery. So if you've had surgery before of your small intestine and you have adhesions, a sort of scar tissue formation, it would be difficult. There's potentially the capsule can get trapped, and then we have to go in and fish it out. But in some patients that we suspect may have that, there's something called a patency capsule, which is a sugar pill, which you ask the patient to swallow first. And if it gets stuck, it just dissolves. And then you know that that patient is not a candidate for video capsule endoscopy. You've got to use something else. And we'll talk about some of the other things you can do. So you've done repeat upper endoscopy and colonoscopy. You've put in a capsule. You can also do a deep enteroscopy. Now, deep enteroscopy, we use balloon-assisted or tube-assisted. So these are longer endoscopy scopes, which have a balloon attached to the end. That's a single balloon. Or they could have two balloons, which you call a double balloon. And basically, we use this to examine the small intestine by inflating the balloon. That gives it some anchor. And telescoping the scope through the balloon to pleat the small bowel over the scope till we get all around to the end to where we want to visualize. So like I said, we advance the scope through the intestine by pleating it over the scope. And for this, we can use to evaluate places that the upper endoscopy and the colonoscopy could not reach. Now, there are two approaches. We can either go antigrade from the mouth down into the small intestine. Or we could go retrograde from the anus up into the small intestine. Now, what determines whether we go antigrade or retrograde? What we find on capsule. Remember I said earlier on, a capsule can give us an estimate of where in the colon. So if it's much closer to the mouth, we start with antigrade. If we think a lesion is closer to the anus, then it's easier to get to the lesion from the rectum. So this is what a double balloon, this video shows you. So as you see, they deflate the balloon, pass the scope through, inflate the balloon, deflate the second one, pass the scope through. And that way, you're able to pleat the small bowel over the colon. So rotational endoscopy is also another form of deep endoscopy. And it involves a rotational clockwise and counterclockwise maneuvers. And rotating allows the spiral to pleat the small intestine and the colon in a rapid and controlled manner. So this is another diagram of what the rotational endoscopy looks like. And these, like I said, are ways in which we try to evaluate the small bowel. So after you've completed your deep endoscopy, the image, that's the fluoroscopy view of how and where the scope is in the small bowel. You can perform interventions by inserting tools through the working channel. So this is using a bipolar probe to try and treat a bleeding lesion in the small bowel. This is a small bowel tumor. You're able to take biopsies and make a tissue diagnosis and determine what exactly, what type of tumor it is before you decide on definitive surgery. So to recap, evaluating the obscure GI bleeding, we do a repeat upper endoscopy and colonoscopy. If we don't find anything, we deploy the capsule. If the capsule finds a lesion, we perform deep endoscopy to either treat or take tissue biopsies for diagnosis. Radiology is also another imaging modality we could use. And this is called a tagged RBC scan. So in patients with overt bleeding who have had a bidirectional endoscopy, where we haven't been able to find a source of bleeding, a tagged scan is a very valuable tool which you could use. And this involves using tagged RBCs. So the right blood cells are mixed with a radioisotope, a radioactive material, and then you perform a scan that tries to locate where the bleeding is. So this is the abdominal aorta. You have the iliacs. And this is what we'll call a positive scan. So you could see some extroversation of blood suggesting that this is, in this territory, is where the bleeding is. Now, some of my colleagues call this an unclear scan because it tells you that it's bleeding, that there's bleeding, but it doesn't tell you exactly where it is. So you have an idea of which territory it is. But it's still helpful all the same because our interventional radiology colleagues can target that area and try to find where the blood is in that area. And as you see, rather than looking all over for the bleed, you have a much smaller region to try and target, to try and identify where the bleeding is coming from. Angiography. This is actually more specific and more targeted. And this actually involves using radio contrast to try and locate the blood vessels and identify where the bleeding may be coming from. So as you would see, that's the angiography image. And this branch here, you could see extroversation of blood. And that's where the bleeding is coming from. And once you identify that with the interventional radiologists, they're able to put in a coil to stop the bleeding. And so that's another way in which we identify small bowel bleeding and treat it. So in this case, angiography actually is the preferred option if the patient is hemodynamically unstable, meaning their blood pressure is crashing and you need to do things more urgently. And also if the patient is bleeding a little bit more briskly, angiography is the way to go. So the treatment depends on the etiology and severity of the bleeding, like I said. In some patients which you may just give iron, meaning they've lost a little bit of blood and you don't think that they're in any threat to life and limb, iron supplementation may be enough to increase the patient's blood count. Some patients that bled a little bit more would need blood transfusions. So blood transfusions are another way to restore the patient's effective blood circulation while you look for other interventions. Endoscopy hemostasis. You do an endoscopy, the patient is actively bleeding or has what we call high-risk features of bleeding, and you try to stop the bleeding either by clipping, cauterizing, which we have discussed earlier on, or hemospray, for the gentleman who talked about hemospray. And then you have the radiologic angiography embolization, which is what I showed you. We identified the area for bleeding with angiography, we placed a coil to stop the bleeding. And last resort, obviously, will be surgery. These are for patients that have consistent and persistent bleeding where we haven't been able to find a source. And this is bleeding that's hemodynamically significant and causing a lot of problems. Case in point, about a week ago we had a patient like that at my institution. The patient had a total of 26 blood transfusions, eight EGDs and colonoscopies, two capsule endoscopies, and we still couldn't find where the patient was bleeding from. So eventually the patient had to go into surgery, have laparoscopy, and we did an intraoperative endoscopy while the surgeons were there to try to find it. Eventually we found it, and the patients had surgery to resect that portion of the bleeding. So these cases can be pretty challenging, just to reinforce that point. So small bowel obstruction, this is mechanical obstruction or functional obstruction, and this is prevention, the normal transit of digestive products. It's a medical emergency. So these are patients that have something causing their intestines not to move in the right direction. They present with abdominal pain, abdominal distension, nausea and vomiting, and they can be constipated. So what are the causes? Adhesions is the chief cause. So adhesions in patients, there's a scar tissue formed in the intestines in patients who've had previous bowel surgery or have had significant infection or inflammation in the intestines. So these adhesions basically tack down the intestines and prevent the normal peristaltic motion. So these patients can definitely get backed up and have significant symptoms. And with increased distension and obstruction, they actually cause a perforation, and contents of the intestines may spill into the intra-abdominal cavity and cause really severe illness. The other causes are hernia. So a hernia is an outpouching of the intestine through a defect in the anterior abdominal wall. These hernia can be symptomatic because they can get trapped and obstructed, and that can cause problems. Small bowel tumor is also another cause of small bowel obstruction. If the tumor is large enough, it could cause blockage of the lumen of the small intestine and cause problems. Interception, this is a phenomenon where a part of a small bowel telescopes into the other. So you can see that, and it's due to abnormal motility of the small intestine. So this proximal part telescopes into the distal part and causes an obstruction, right? The one telescoping is called the intertuceptum, and the one receiving is called the intertucepium. Fancy medical words for saying that one part of the small bowel is telescoping into the other. And that causes an area of obstruction, which can cause symptoms. Treatment of that's typically, it could resolve with bowel rest, but typically they undergo surgery. So strictures, so this is another cause of small bowel obstruction. It's a narrowing of the lumen of the small bowel, right? This could either be a benign narrowing, or it could be due to a tumor or cancer. This image shows you the stricture, which is this thin portion, as you can see proximally there's dilation, and also that's the distal end. So that's a stricture, and you can see why food and digested material will not be able to transit through this, and that causes problems. A bezoar, so a bezoar is an insoluble concretion or accumulation of material, which causes a bowel obstruction. So this could be indigestible food, it could be a mixture of food and other things that are swallowed, and basically it forms a real big rigid wall that prevents contents from moving through the stomach or the intestines. So how do we diagnose small bowel obstruction? The x-ray is classic, and it's easy, ready to use. You can find it in the ER. And basically your hallmark finding is what we call air fluid level. So you find a distended small bowel, as you can see, it's ballooned out, but you can see air and liquid, and that's what we call air fluid levels. And this is characteristic and diagnostic of a small bowel obstruction. A CAT scan can be used, and if you see with a CAT scan, not only do you see the dilated small bowel loops, you can also see what we call a transition point. So this is the point of, and that's the area of obstruction, physical obstruction that prevents contents that are more proximal from moving distally, and that transition point is located. The CAT scan is excellent for detecting that, and also to see if there's anything around. So that transition point, you may see that there may be a mass or tumor around there that's pressing on the lumen. Sometimes you cannot see that, but most of the time the CAT scan is useful for detecting that. So how do we treat? So you mentioned earlier on nasogastric tube decompression, and basically for patients who have small bowel obstruction, we do the NG tube decompression to basically take out air and excess contents from the stomach. That will correct the electrolytes, because these patients also have a lot of electrolyte derangement. And then we hydrate them, give them enough fluid to make sure they are not dehydrated and continuously ill with that. That in most times is able to do it, resolve the obstruction, especially if it's a partial. So you could have a partial small bowel obstruction, meaning it's not completely obstructed, or you could have a complete obstruction, which means it's completely obstructed. For the partials, this may be able to solve that. For those with complete obstruction, they're going to need surgery. And this type of surgery, basically, you can see the diagram shows you. It takes the resect, removes the obstructed part, and they're able to reconnect the bowel. So that's the area that has the problem, which has been resected. You could also do a small bowel enterotomy, and basically make an incision, remove whatever it is that's causing the obstruction, and suture them back. Mesenteric ischemia. So this is inflammation of the injury to the small bowel due to inadequate blood supply. And this diagram shows you the blood supply of the intestine. You have three major arteries, the celiac artery, the superior mesenteric artery, and the inferior mesenteric artery. Those are the three major arteries that supply the GI tract. Mesenteric ischemia can either be acute or chronic. So the acute is typically due to a blood clot in one of those major arteries. It presents with acute severe abdominal pain and shock. The physical exam, the classic thing is that the patient's complaining of a lot of more pain than their examination will suggest. So that's always a clue to think about acute mesenteric ischemia in the right patient. For chronic, it's due to atherosclerosis, the buildup of plaque in the big vessels of the intestine. This patient's been presented with what we call postprandial abdominal pain. That's pain after eating. They lose weight because they become afraid to eat, because they can associate the pain with food intake. And they have that fear of eating. And that's always actually very indicative that these patients may have chronic mesenteric ischemia. We call that postprandial pain abdominal angina, almost similar to the angina you get with patients with heart disease. When they walk, they get pain. These patients, when they eat, which demands a lot of blood flow to the intestine, but because that blood can't reach the intestines, they have pain. So acute mesenteric ischemia, this shows the blockage of the SMA. And as you can see, in the areas where that big blood vessel supplies, you can see this dusky coloring, which means that those areas are starved of oxygen and blood. And what tends to happen is that those areas eventually die and become necrotic. And as you can see, this is the gross image of that. And you can see the viable bowel. And you can see that this is dead bowel. So this will have to be resected. And they'll try to see what's left of the viable bowel so that the patient can continue to live their life. So chronic mesenteric ischemia, like I mentioned, it occurs from narrowing of at least two of those three big arteries. So the body is so well-designed that if you have just one blockage, a chronic blockage of one of those three major arteries, you're able to form new channels, something we call collaterals. And then the other two can keep you going. But if you have two or more of those vessels blocked, then you're going to have symptoms. So for chronic mesenteric ischemia to occur, patients have to have at least two, either the SMA or the IMA or the celiac or the IMA compromised before you have symptoms. Okay? And so how do we diagnose this? An angiogram is very important. A CT angiogram also, or MRI or Doppler ultrasound. So any of these four modalities can be used to diagnose chronic and acute mesenteric ischemia. As you can see with the angiogram, it's important that once you locate the area, you're able to intervene either by placing a stent to open up the vessel that's occluded. And that in itself is a treatment on its own. This is just a gross image showing that. At that point, we'll stop for questions. Yeah? Do the clips cause a problem if they're in there? Like you're leaving the clips and it looks like it would catch things, right? Is that a concern? Not that much. No. I mean, the types of clips we use, yes, they will fall off with time. Whilst they're there, they don't cause any problems. And sometimes when we do endoscopies, we see clips that were placed by some of our colleagues. We just leave them alone, right? We don't try to remove the clips, right? Because that could just trigger another episode. But for the most part, when we deploy clips, we leave them in. They fall off in the stool over time. We typically will say it takes about four to eight weeks for them to fall off. Sometimes we see them at endoscopy much longer after the intervention has died. They're not ferromagnetic, so there's no issue about people going into MRIs with the clips. Are gastroenterologists using ICG to identify tissue perfusion, or is that more colorectal surgeons, bariatric surgeons? So are you measuring, are you using ICG? On endoscopy? Well, you showed slides of the anastomosis up there. Is that something that, well, yeah, I guess for that reason, you're right. Well, not on endoscopy. We're not routinely doing that. The colorectal surgeons, the bariatric surgeons, may want to know tissue viability because, as you know, with any anastomosis, it's a false connection. And obviously, the blood supply is not as efficient as if it was a native organ. And that's what actually predisposed, especially in those patients with upper, who've had a Roux-en-Y gastric bypass, they're predisposed to anastomotic ulcers due to that ischemia. But that type of ischemia is not what I was referring to when I was talking about mesenteric ischemia. This is blood vessel ischemia. And the reduction in blood flow is due to anything that blocks the lumen of the vessel. So we're not talking mucosa, we're talking vessels. Yeah? When two of those three arteries are clogged and, you know, intervention needs to be made, are you placing the stents or clearing the arteries? Who does that refer to? No, it's the vascular surgeon. So the vascular surgeons are the ones who do the mesenteric surgery, right? So they place the stents as well. Our role is that these patients present with abdominal pain, and the onus is on you to figure out why they have abdominal pain. And like I said, for their symptoms, that may suggest certain etiologies, and then you investigate with your endoscopy and your CAT scans. And with a CTA, once you make that diagnosis that this patient may have mesenteric ischemia, you would refer on to the vascular surgeons who will take over from there and do what they need to do. They need to place a stent, they'll do that. If they need surgery, they'll do that.

gastroenterologist

celiac disease

obscure GI bleeding

small bowel obstruction

mesenteric ischemia

autoimmune reaction

intestinal disorders