We're talking about the small intestine, and as Gauri had mentioned earlier on, she talked about the anatomy and the basic physiology of the small intestine. I'll be talking about the pathology and the possible conditions that can happen when things go awry with the small intestine. So we'll start first with a couple of questions. In the small intestine, what type of endoscope can be used to view at least part of the small intestine? The correct answer is D, all of the above. You can use the enteroscope, the colonoscope, and the gastroscope, which is the upper EGD scope to view different parts of the small intestine. As you know, the EGD will get to the duodenum, and you may be able to stretch it to the third part of the duodenum as well. The enteroscope will go all the way into the proximal jejunum, the mid-jejunum. And the colonoscope can be used to access the terminal ileum, which is the end portion of the small intestine. The second question, in the small intestine, diarrhea can occur as a small intestinal disorder. Is that true or false? Excellent, yes, diarrhea can occur as a function of the small intestinal disorder. So you're very familiar with this schema. We'll move ahead, and we'll talk about the outline of the talk. We'll talk about celiac sprue, obscure GI bleeding, small bowel obstruction, and mesenteric ischemia. Celiac sprue, this is an autoimmune disease of the small intestine, and it occurs as a result of exposure to gluten, which causes an immune system response and inappropriately damages the small intestine. The etiology of this disease is unknown, but we know that there is a genetic predisposition. It's not a classical Mendelian inheritance pattern, but we know that patients that have a mutation in HLA subclass, DQ, and or D8 may be predisposed to responding in this way when they ingest gluten. So what is gluten? Gluten is found in wheat, barley, and rye. It gives the doughy texture, and it's also found in cosmetics, such as hair products, skin products, and that's very much ubiquitous all around in the environment. Patients with celiac disease could be asymptomatic, they could have no symptoms at all, and what we know is that patients are diagnosed even much later in life as a result of asymptomatic celiac disease. They could present with fatigue, anemia, abdominal pain, cramping. Diarrhea is the classic symptom. People ingest gluten, and they develop chronic diarrhea, which can be really debilitating and cause a lot of problems with quality of life. Gluten is the classic pathophysiology, in that these patients, when they react to gluten, they're unable to absorb ingested food, and this manifests as different things, such as weight loss, growth failure in children, osteoporosis. How do we make a diagnosis of celiac disease? We can do a blood test, serology testing, and there are a varied number of tests, a combination of tests that can be done, but classically, any one of these can be used to diagnose celiac disease. The endometrial antibody is very specific, but not very sensitive. A tissue transglutaminase antibody is very sensitive, and typically, that's the one most people go for. It's got a bit of a 95% sensitivity for diagnosing celiac disease, but the combination of a serology test and biopsy is the gold standard for diagnosing celiac disease in adults. In children, you may be able to get away with just a positive tissue transglutaminase antibody in the right clinical setting in a child that presents with diarrhea as a consequence of ingestion of gluten. So these are endoscopy features of the small bowel. The image on the far left there shows a blunting of the plicae secularis, which you could see on endoscopy. The middle image is showing a scalloping, which is another endoscopy feature of patients with celiac disease. And that image shows complete atrophy of the duodenum and nodular mucosa. So what's the treatment for celiac disease? It's strict avoidance of gluten. We encourage patients to be on a gluten-free diet for life. And in most patients who are adherent to this type of dietary recommendation, they're able to prevent all the deleterious effects of the disease. Obscure gastrointestinal bleeding. This is bleeding from the GI tract that persists or occurs without an obvious etiology despite endoscopy. So these are patients that present with gastrointestinal bleeding, either hematemesis or melanoma. They get an upper endoscopy and a colonoscopy, but no source of bleeding is found. And this occurs in approximately 10% of patients with gastrointestinal bleeding. This bleeding could either be occult, meaning that this patient may present with iron deficiency anemia but no overt bleeding, or it could be obscure overt, meaning that you've seen blood or you've seen blood or the patient has reported blood, but on endoscopy evaluation you don't find any source for the bleeding. What are the causes of obscure GI bleeding? So we have Crohn's disease, angiotensia, as mentioned earlier on, ulcers. This could be ulcers in the jejunum or any part of the small intestine. A dulafoil lesion, which is a submucosal vessel that bleeds rapidly and can cause very significant hemodynamic changes in patients. Or Meckel's diverticulum. This is seen most regularly in young children, although adults can present with Meckel's diverticulum. And it's the presence of ectopic gastric mucosa in part of the small intestine, which will bleed intermittently, and it's pretty difficult to diagnose. Then small bowel tumors, tumors of the small intestine can also cause obscure GI bleeding. How do we evaluate patients presenting with obscure GI bleeding? You repeat the upper endoscopy and colonoscopy, or you do a capsule endoscopy. A capsule endoscopy, as the video shows, this is a miniature camera, pill size, which is swallowed and this goes all the way through the small intestine and is expelled in the feces. The pill records the images and is recorded onto a device. And once the pill and once that device is completed to run, the images from the pill from the device are downloaded on the computer and we're able to visualize. And this way we're able to diagnose very different conditions. As you would see with that video, this patient had like a small bowel ulcer, which was possibly the reason for the GI bleeding. Other things you can diagnose, you could diagnose active bleeding, so sometimes the capsule endoscopy will reveal a site with active bleeding. You could diagnose angioectasias, which are mucosal abnormal blood vessels that will bleed intermittently. You could diagnose small bowel tumors or small bowel ulcer. What are the disadvantages of capsule endoscopy? It only examines the small intestine. You cannot take biopsies. There's a long reading time and some of these studies on average are about six hours, so you may have to sit and watch and go back and forth in order to detect the pathology. There's the risk of retention of the capsule, particularly in patients who have had small bowel surgery, where they've had an anastomosis and maybe they have intra-abdominal adhesions, which may increase the potential for the capsule to get stuck. So in evaluating patients with obscure GI bleeding, we can repeat the upper endoscopy and colonoscopy. We're able to detect a source, and sometimes if we're not, we proceed with the capsule endoscopy. The capsule endoscopy is important in two ways, because we don't have any scopes that can completely visualize the small intestine, so the capsule also acts as like a little roadmap telling us where we may be. So if the abnormality is more proximal, you may want to approach with your enteroscopy via the oral route. If the pathology is more distal, you may want to approach your enteroscopy via the colonoscopy route. And so these are the devices for assisted enteroscopy. You have the double balloon enteroscopy, you have the single balloon enteroscopy, and as the names imply, the single has one balloon, the double has two, and you have the rotational enteroscopy. So with balloon-assisted enteroscopy, you advance this scope through the small intestine by either inflating and deflating the balloons. The balloons enable you to anchor in the small intestine and advance the scope, and you're also able to pleat and push and pull the endoscope by means of an overtube. Now with these devices, you can evaluate the entire small intestine that is not reachable with an EGD and a colonoscope, as I explained earlier. Antigrade through the mouth if your capsule shows you that that's where the lesion is. Retrograde through the rectum if your capsule identifies a source closer to the colon. So this video basically shows what the double balloon does. As you see, when you inflate, you advance the scope, and then you inflate and deflate the scope, advance the scope that way. So deep enteroscopy, as you can see, you can also perform interventions. The additional benefit of this is you can perform interventions, and you can either use thermotherapy to cauterize angiotensic lesions, or you can take biopsies. For example, this small bowel tumor, which is a cause of obscure bleeding, you can take biopsies, identify the pathology, and then you're able to plan for a surgical resection. So what else can we do? We could do radiologic interventions in evaluating patients with obscure jaw bleeding. This is a tagged RBC scan. This is a nuclear medicine scan, and it's very valuable for detecting sources of bleeding in patients that are bleeding at a rate of 0.1 mil per minute. The image on the left is the early phase. The image on the right is the late phase. And as you can see, the site of GI bleeding is identified. This test is done by taking a little bit of blood in the nuclear medicine department, mixing that blood with a radioactive tracer, and then injecting it back into the patient and taking scans at timed intervals. This is very important in evaluating patients with obscure bleeding because, you know, it enables us to identify a source which we can now pursue in order to do curative therapy. You can't do any interventions with a tagged scan, but at least it enables you to localize the source. Angiography. This is more effective because this has both diagnostic and therapeutic potential. So angiography is typically used in patients that are bleeding at a rate of 0.5 mils per minute. And those patients typically will have hemodynamically significant gastrointestinal bleeding, such as hypertension, tachycardia. And basically, it's able to identify a source of bleeding, for example, where the arrow shows the bleeding vessel. And then you can apply coils to stop the bleeding. And so that's the benefit of angiography, identification of a source and therapeutic intervention. So treatment. This depends on the etiology and the severity of bleeding. In patients that have obscure bleeding due to iron deficiency anemia, iron supplementation may be chronic in those patients, especially if you think they have angioctasias that require repeated endoscopy interventions to treat. Blood transfusion to restore the hemodynamic stability. Hemostasis for patients that you identify a bleeding lesion where you can intervene upon. Radiologic angiographic embolization. Or in worst case scenarios, surgery. Small bowel obstruction. Mechanical or functional obstruction of the small intestine. And this prevents normal transit of digestion. It's a medical emergency. There are many causes of small bowel obstruction. Main symptoms are abdominal pain, abdominal distension, nausea, vomiting, and constipation. Adhesions are a very common cause of small bowel obstruction. And you know, this is scar tissue that's formed in patients after they've had intra-abdominal surgery at some point. And what the scar tissue does is that it restricts the normal peristaltic movements of the intestines. And they may be a point where the contents are obstructed and typically will have what's described as a transition point. A hernia. And you know, a hernia is the outpouching of the intestine through a potential weakness in the anterior abdominal wall. As the diagram shows, you can see the loop of bowel protruding out of that potential space and the weakness in the abdominal wall. Now, typically, hernias could be reducible, meaning that they protrude and they go back. The emergency occurs when the hernia is non-reducible, they're strangulated, or they're obstructed. And that's an emergency that will require either surgical intervention. Small bowel tumor also can act as a source of small bowel obstruction, as you see the tumor on that endoscopy image. And that's the tumor when that portion of the bowel has been resected. Intersusception. This is the telescoping of the small intestine through itself. Typically, there's a lead point, which could be due to a tumor or some sort of polyp, a large polyp, or even a lipoma sometimes. And what happens is that the small bowel, part of the small bowel telescopes into another part of the small bowel. And that causes anitis of obstruction. And this also may present as an emergency that requires surgical correction. Strictures. Strictures could be formed as a result of inflammation from conditions like inflammatory bowel disease or small bowel enteropathies. These are inflammatory processes in the small bowel that may be due to infection or due to an autoimmune process. And what basically happens is that there's scarring and luminal narrowing, as the radiographic image shows. You can see that portion of a long stricture, which prevents the bowel contents from bypassing that. And that's the area of obstruction. Typically, that stricture will need surgical correction. Sometimes they're able to dilate and put a stent, but it all depends on the type of stricture. A bezoar. So a bezoar is a complex mass of undigestible food. It could also contain foreign bodies, such as hair, ingested non-dissolvable materials. And these form a mass in the bowel and obstruct the small bowel. And this will present with obstructive symptoms that we described earlier on. So how do we diagnose a small bowel obstruction? Typically, the history is classical. Examination of the abdomen, the x-ray, can be useful in that if it shows dilated small bowel loops and air fluid levels. So what we see here, the lucent parts at the dilated small bowel. And if you see that, there's like a line across there. And that's the air. The air is above, and the fluid level is described there by the meniscus showing that demarcation. And if you see this, it's classic for small bowel obstruction. However, the x-ray does not give us any idea of what the etiology of the obstruction is or what the nearby structure is here. And that way, the CT scan is superior in that it will show us the dilated bowel. It will also show us the transition point. That's where in the small bowel the obstruction is. And it's able to identify the etiology. So if there's a mass around that area of the transition point, it will be able to tell us that. If it's actually a blood clot in the vessels around there, it will also be able to tell us that. So the CT scan is actually very, very informative for diagnosing small bowel obstruction. And when we do diagnose a small bowel obstruction, how do we treat it? We insert a nasogastric tube. And the whole purpose of that is to decompress the gastrointestinal tract, remove excess air that's accumulated or fluid that is accumulated. You collect the electrolytes because these patients become very significantly electrolyte depleted. And you give them IV fluids to rehydrate them. Treatment. This could be surgical resection of the small bowel, as the diagram there shows. The obstructed part is resected. And then they reconnect the both viable parts together. And there's a process called a small bowel enterotomy. Mesenteric ischemia. This is inflammation and injury to the small intestine due to inadequate blood supply. This is a rare condition. And when I teach my fellows, I tell them it's a significant, uncommon, but significant diagnosis that they shouldn't miss. So it's inflammation and injury of the small intestine due to inadequate blood supply. So the blood supply of the small intestine is primarily from the superior mesenteric artery with collaterals from the celiac artery. That's the superior and inferior pancreatic arteries. You've got the inferior mesenteric artery. And those are the main blood vessels supplying the small bowel. So what happens? Inflammation. It could be acute or chronic. If it's acute, it's typically due to a blood clot in the SMA, which is superior mesenteric artery. And you see this in patients that have either atrial fibrillation or sort of low ejection fraction heart failure. And it's acute, severe abdominal pain and shock. Typically on physical exam, you'd say they have abdominal pain that is out of proportion to the exam. So this patient in excruciating pain. When you examine their abdomen, it's relatively benign. Those are the patients with acute mesenteric ischemia. Those with chronic mesenteric ischemia typically have a history of arteriosclerosis and maybe interventions to their aorta. And they have a lot of plaque, heavy plaque, arteriosclerotic disease. This patient is presented with a classic postprandial abdominal pain. So they have a meal. And a couple of hours after, they endorse pain. Some may sweat. Some may also have a fear of eating, something called scytophobia, because they associate food and eating with that excruciating pain. They also lose weight as a consequence of not eating. And those are the two major presentations, acute and chronic. In the cutic ischemia, this diagram shows the clot in the SMAs. Typically the first 10 centimeters of the SMA that gets occluded. And as you see, there's a reduction of blood flow to other parts of the small intestine. This gross picture shows a patient with acute mesenteric ischemia. And as you can see, the dusky and edematous part of the bowel is the ischemic portion. And it's typically non-viable tissue, because there's cell death there. And the pink and bright areas are the viable parts of the small bowel. And so the surgeon would typically try to resect the non-viable parts and preserve as much viable bowel as possible. So chronic, like I spoke earlier, it only happens when you have at least two of the three major arteries. And if you go back to the schema I showed you, the SMA has to be blocked, the celiac or the IMA has to be blocked before these patients will develop symptoms. And like I said, it's seen in patients with significant arteriosclerosis. And the abdominal pain is really due to that poor supply of blood to other parts of the intestine. Diagnosis, imaging, angiogram, CT angiogram, MI angiogram, or Doppler ultrasound. This will identify the artery. And this image shows a clot in the SMA there. The treatment could be angiography or surgery. With angiography, the goal is to try to reopen up that blocked vessel, which could be either due to stenting, they could put a stent if it's not completely occluded, or surgery, which the aim there is to resect all the non-viable bowel and do an interval staging operation where after the patient is recovered, they can reconnect the patient back. So that's all I have. Thank you.

small intestine

endoscopes

celiac sprue

obscure gastrointestinal bleeding

small bowel obstruction

mesenteric ischemia