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Lower GI Anatomy & IBS vs IBD

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Summary

This on-demand teaching session provides an in-depth educational walkthrough for medical professionals on the anatomy of the gastrointestinal system, focusing on the innovations and arterial supply of various parts of the system. The lecture covers the celiac trunk, superior mesenteric artery, and inferior mesenteric artery, taking care to detail their respective branches, supply areas, and related diseases. The session also includes learning on watershed areas like the splenic flexure and rectosigmoid junction. Furthermore, the professor discusses the implications of pathology in different sections of this system, with a focus on rectal hemorrhoids and ischemic colitis. The anatomy session wraps up with a comprehensive dissection of histology of the duodenum, jejunum, and ileum. This course is ideal for medical professionals, particularly those needing a better grasp on gastrointestinal anatomy for surgeries and clinical diagnoses.
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Learning objectives

1. Learners will be able to accurately describe the anatomical divisions of the digestive tract, including the foregut, midgut, and hindgut, and their corresponding arterial supply and innervation. 2. Learners will be able to understand and interpret the relevance of arterial and venous supply to different areas of the gut in the context of surgical interventions and possible complications. 3. Learners will be able to identify key histological features and differences of the duodenum, jejenum, and ileum, and understand the significance of these differences in disease processes such as Crohn's disease. 4. Learners will be able to diagnose and manage common pathologies of the digestive tract, such as ischemic colitis, by interpreting clinical signs, symptoms, and laboratory values. 5. Learners will be able to interpret and apply anatomical and physiological knowledge of the digestive tract, including areas of particular vulnerability to ischemia and the different innervation and blood supply above and below the pectinate line, in clinical practice and decision-making.
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The following transcript was generated automatically from the content and has not been checked or corrected manually.

Hold on. And then the hi gut is the distal third of the transverse colon, descending colon rectum and anal anal canal. So essentially, as we know that this is from kind of when you're made as a fetus. And it's important when we're looking at the innovations and the arterial supply. So the four gut is uh supplied by the celiac trunk. It is innervated by the vagus nerve and uh it's venous return is via the portal vein. Um And we know that the liver is in this kind of top one here. The midgut is supplied by the sma um which comes from L1 of the abdominal aorta. It is innervated by the vagus nerve and its venous return is via the superior meto vein. The hindgut is innervated by the IM which is coming from L3. And then this is innervated by the pelvic splanchnic nerves. And these are drained by the inferior mesenteric vein. So these are kind of just some key facts to know um particularly the arterial supply I'd say is the most important out of these three just to know um which parts of the gut is supplied by what So if we go into a bit more depth about the abdominal aorta, we know that there's some different branches. The key ones, you've got the celiac trunk at T 12, we've got the inferior at the superior mesenteric artery at L1 and the renal arteries at L1, the go gonadal arteries. So to like the testes and to the ovaries is at like L2 and then the inferior mesenteric artery is at L3. So starting with the celiac trunk, um kind of looks quite complicated when you first look at it. But actually when you break it down, it's not too difficult. So the way I like to remember is the celiac trunk comes off at T 12 and it's got three main arteries. And when you think about it, you've got the stomach artery as the first one, obviously in the name, it supplies the spleen. But what's directly next to the spleen is the greater curvature of the stomach. And it also supplies that by the short gastric, the left gastric artery, I like to remember this is L and L it supplies the lesser curvature of the stomach. Um And also it kind of comes through to join onto the common hepatic artery up here. And then you've got the common hepatic artery which is supplying the liver, but it's also supplying this gastroduodenal artery here. So the duodenum into the gas right gastro work at the bottom of the greater curvature So, whilst it looks quite complicated, I think when you break it down into this diagram, and you can just draw it out quite quickly. It's actually quite easy to remember moving on to the superior mesenteric artery. So again, when you've learned from the start, the kind of key structures that each supply, it's then easier to determine which artery supply what. So it looks complicated. We've got five arteries here coming off the superior mesenteric artery. Um We've got the inferior pancreaticoduodenal artery in the name, it's supplying the pancreas and the duodenum. So the distal part of the duodenum, um because as we know, the proximal part is supplied by the celiac trunk, the distal part supplied by the sma, we've got the head of the pancreas and the uncinate process part of the pancreatic bit. So that's not too bad to remember the Junine ileal arteries, self explanatory, uh supplying the Juju and the ileum. We've then got the middle colic artery which is supplying um the proximal two thirds of the transverse codon. And as we know, the distal third of the transverse codon is supplied by the IMA which will come to, we've got the ileocolic artery. Um I've seen this question because obviously, it's kind of a random name. Um I've seen kind of questions about asking about the supply of the appendix. So that's the ileocolic artery and that is also the cecum and the ascending colon around it. And then the right colic artery is the ascending colon. So, it's important to remember these, um, looking at surgical landmarks. If we're doing, um, like a hemicolectomy or Hartman's, uh, any kind of bowel surgery, it's important to know which arteries need to be ligated or need to be. Um, you need to be aware of when you're, um, doing surgery. So, obviously, it's important to know. So then finally the inferior mesenteric artery, this is probably the easiest one just split into three. We've got the left colic artery. So if you just think left side of the colon, we've got the distal third of the transverse colon and the descending colon. Um We've got the sigmoid arteries. So obviously, the sigmoid colon and part of the descending colon as well. And then the superior rectal artery, which is the rectum above the um pectinate line, which will also come to. So we're gonna start with our first SBA today. Um We've got a 70 year old man with a history of heart failure, uh who presents to the emergency department with sudden onset crampy, left sided abdominal pain and blood in the stool. He's got a raised lactate on his bloods. He's also a afebrile, he's not got a temperature. What do we think is the most likely diagnosis about a? Oh, does anyone want put your pulse, please? Ok. We're just gonna move on. So if you answer that in your head, that's great. Um The answer is ischemic colitis. So what's important to remember about the colon? Um Is there are these watershed areas? So we've got the splenic flexure and we've got the rectosigmoid junction and these places are vulnerable to ischemia because they're only supplied by terminal branches of arteries. So it means that there's not collateral circulation. So if part of an artery is blocked, then it means that, oh, there's the b we'll do that. Ok. Oh, no, I think we'll come back to the SBA. Um Thank you. So, um a common stem for these kind of questions is someone might have atrial fibrillation. So they might um be at risk of these kind of clots and they might have a increased lactate because obviously, if you're having an ischemia to a part of the bowel, then it means that your lactate levels can be increased. So there's some kind of key things to look out for in ischemic colitis. Um And obviously the area as well. So I think the splenic flexure is the most common area and then the rectal signal junction is also, is also vulnerable to it as well. So as we talked about earlier with the anal canal, um we've got the pectate line which kind of separates it to above and below. So if we're looking at the innovation above the pectinate line, we've got visceral innervation and it is supplied by the superior rectal artery, which is the branch of the I that we've just discussed it's been a supply of the superior rectal vein. And in terms of below the pectinate line, the innervation is somatic. So that means as we know, it's to do with the skeletal muscle, it's more painful. Um The arterial supply is the inferior rectal artery, which is a branch of the pudendal nerve. And the venous supply is the inferior rectal vein. Something key to remember. Um In terms of this is that when uh someone has a pudendal nerve block in pregnancy, for example, then they might have some sphincter problems like the external anal sphincter because of the uh the er because of the supply of the pudendal internal pudendal artery. Um if someone's got an infection or a cancer, say above or below the pectinate line, then we might be able to determine this clinically above the pectinate line. Someone might have lymphadenopathy in the internal iliac lymph nodes. Whereas below the pepsinate line, someone might have lymph lymphadenopathy in the superficial inguinal lymph nodes. So that's a key differential there. Um As I was just saying to do with the visceral and the somatic innervation above the pep state line, we might have internal hem hemorrhoids and these are often described by patients as itchy rather than painful. Um Whereas below the pectinate line, we cal these external hemorrhoids and these are often very, very painful um because they're innervated by the somatic. Um So that's just something to point out there. So we're going to move on to histology. Now, um Another SBA, if we could have a poll, please. Um, a 50 year old man with Crohn's disease has a colonoscopy and biopsy under the under the microscope, pas patches are visible. Which area of the gut do we think this sample is taken from? We can't see anyone's answers in the poll. So just feel free to give it a go. Um We can't see what anyone, anyone puts. Yeah, they have like 10 more seconds. OK. So I think a few people might have got the answer there. The answer is the ileum. I think most people want for, for D which is the transverse codon will come to the histology now. So Pear's patches are these kind of lymphoid patches that we find in the ileum. They're important because they help to maintain the intestinal flora. So maybe preventing some gi infections. Um But these are relevant because when we're looking on histology and we see them, we know which part of the bowel they come from because they're only found in the ileum. So some of the key histology, I know that everyone hates histology. But I've just tried to make this as simple as possible. Um A key thing to know about the duodenum is that it has brunner's glands, they're located in the submucosa and they, they secrete this kind of alkaline fluid called nucin. And this helps protect the duodenum because obviously, as we know from the stomach. We have this very acidic kind that is secreted into the duodenum. Um And if that was just against the mucosa, then it would probably kind of wear away uh wear away at it or eat away at it because it's very acidic. Whereas we have this um mucin or alkaline fluid that kind of lines it to protect the mucosa moving on. We've got the Judum. So the way you can differentiate this is because they do not have pairs patches, they do not have runners glands which are the two things found in the ileum or the duodenum, either side of the Judum. They also have these PK circularis which are uh mucosal folds. So that's something to differentiate there. The ileum has these pairs patches, as we just said, uh they're important for maintaining the intestinal flora and prevent infection. The Judum versus the ileum is often a common question. Um The way that I like to remember this, it might not work for you, but the jun is a longer word than ileum. So I like to think of it as wider, thicker and longer vaso reca. So it's kind of wider, thicker and longer. Whereas the ileum is a shorter word, it's narrower, it's thinner and it's got shorter vaso reca, that's the way that I think of it. It might not work for everyone. Um There's also less fat in the mesentery of the Judum, but there's more fat in the ileum in the mesentery of the ileum. I think if you've done some of the anatomy Practicals, you've looked through the, the, the walls of the ilium in the judgment with the torch. Um It helps you to see it. But yeah, that's just the key differentials there of the two different um structures. And obviously, as we've said, the ilium's got pairs patches and the Judum does not in terms of the colon. Um in the colon, we've got crypts of Lieberkuhn, which are really important because they secrete um mucus from the goblet cells and they have these enteroendocrine cells for absorption in the anal canal. We've got two different types of cells above and below the pectinate line. So above the pectinate line, we've got this simple columnar epithelium. Whereas below, we have stratified squamous epithelium um in kind of column epithelia, we're more likely to see uh adenocarcinomas. Whereas obviously in squamous epithelium, we're more likely to see squamous cell carcinomas. So that's just another clinical point there moving on to digestion. Um I've again tried to keep this pretty brief. Um So when we're looking at the small intestine, we're looking at motility and how food moves through it. There are kind of four key things to know we've got spontaneous contraction in the small intestine. This is where muscles just spontaneously contract even when food is not present, keeping things going. You've got this migrating myoelectric complex, which is important if there's individuals that fast So, when someone's fasting, obviously, there's not food moving through the tract, but these muscle contractions occur every 1 to 1.5 hours. This helps to remove any residual food. And it is most important in preventing the migration of bacteria from the colon up into the ileum and cause an infection. We then got the two plexuses. So the enteric nervous system is important in the motility in the small intestine. We've got the myenteric plexus which is controlling the muscularis externa versus the submucosal plexus, which is controlling the submucosa in terms of absorption and defecation. It's important to know what things are secreted and what things are absorbed where. So I've just done a quick table here just to make it really easy to see. So, in the stomach, we know uh if someone is, has had a very heavy night, they might have alcohol poisoning. This is because ethanol is absorbed through the stomach. So it's very quickly absorbed. Whereas the stomach, the stomach secretes, Pepcid and hydrochloric acid in the duodenum, we've got quite a few key ions here. So iron is absorbed in the duodenum. We've got glucose, chloride, calcium, lactose and fructose, whereas it's secreted is uh bicarbonates and enzymes. Um enzymes quite general. Um as we know things that break down food, jun absorbing the amino acids, the fatty acid and then the fat and water soluble vitamins is important. Uh if someone is got, you know, IBD or disease you know, colitis or Crohn's of a specific part of the, of the, the tract. So, possibly like in the Judum, they've got a very specific area of disease and they may not be able to absorb vitamins properly. And so we might have to supplement those. Um, so if someone's not able to absorb fat soluble vitamins, then it means that their stools will be different and then we'll be able to clinically rectify that by giving them some uh supplementation. Um The Judum secretes bile and it secretes enzymes. The ileum approximately we're absorbing Vitamin C distally, we're absorbing B12 and bile salts. So again, someone might present with a B12 deficiency if they're presenting with something like IBD and the colon, as we know, absorbs water. Again, I think we've talked about the anal canal so many times in this uh in this talk so far. But it is a really important part. As we know for defecation, we've got two sphincters, we've got the internal and the external sphincters. Um they are controlled differently. So the internal sphincter is smooth muscle. It's controlled by the autonomic nervous system, we don't control it. Whereas the external sphincter is voluntarily controlled and it's innervated by the pudendal nerve. So as I said earlier, if a pregnant lady, for example, has a pudendal nerve block during birth, then possibly they might have some um problems with controlling their bowel movements. Um So that's something to be aware of. So things like incontinence. For example, if someone has a pudendal nerve injury, they may have incontinence because they, the internal sphincter works, but they can't then voluntary control the ex external sphincter. Um and here to, to defecate the external sphincter relaxes and the internal sphincter contracts. So last part of the talks about infectious diarrhea, this is, I feel like there's quite a lot in this, these next few slides, but don't get too overworked by it. Um We're gonna start with a SBA. So a 41 year old lady presents the GP with numbness and pins and needles sensations in her feet and hands that's slowly starting to affect the arms and legs. Her only uh past medical history is a few days of an, of an upset tummy last week. What is the most likely cause of these symptoms? Ok. I'm gonna end the poll there. So the majority of you did get that correct. Um The answer is infection with Campylobacter Gey. So this question is getting up, the patient likely has Guillain Barre syndrome. So, um not often, but sometimes if someone has an infection with Campylobacter June and they have um diarrhea, for example, like a tummy illness. Um a few weeks to months later, someone can present with neurological symptoms. Um and this can be Guillain Barre syndrome and it can actually become quite serious. It's important to pick up. So, to make this more clinical when we're thinking about diarrhea and someone's kind of presenting it in the GP. Uh For example, we need to think about specific factors. We need to think about their recent travel history. So for example, Traveler's diarrhea is really common for E coli, um as well as the fact that if you're abroad and maybe you're swimming in water or things like that, there are different bugs that could be more common if someone's had recent gastroenteritis, if they've had recent antibiotic use. So, for example, if someone's had recent antibiotic use, we might think that they're more prone to c diff. So it helps us with our differentials. If someone's had a recent hospital admission, they may have picked something up there. Hospitals are rife for bugs, um, especially norovirus. Um, I was on placement this kind of block and I think every week the ward was blocked off with someone with norovirus, um, particularly over the winter. So that's important to consider as well. And also if someone has underlying, um, bowel conditions. So, diverticulitis, Crohn's colitis, for example, um, those are factors to consider when you're, you're asking someone about these, if they've got none of these, um, then obviously it's harder for you to kind of differentiate things. Um, and the bugs that they might have. Whereas if they be, if they've traveled recently, they were swimming in a water source in Egypt, for example, then you might be able to quickly, um, push your differentials into a smaller list. So there's two types of bacteria that are important to think about. Here, we've got enterotoxic and invasive. So we're going to start with invasive invasive bacteria is due to the invasion of pathogens which actually cause specific damage to the cells of the gi tract which then causes bleeding. So you get blood diarrhea. However, enterotoxic is not the pathogen itself, not the invasion by the pathogen itself that causes harm, but from the toxic that it releases. So when you're infected uh with an enterotoxic bacteria, often the toxin is drawing water into the gi tract, you're not absorbing ions properly. So you're getting very loose stools and you're getting more watery diarrhea compared to bloody diarrhea. So, if someone's presenting with diarrhea, obviously, you're gonna ask them if they're having bloody diarrhea or watery diarrhea. Um if they can see blood in their stool and that helps you to try and differentiate between the two. So some common causes of enterotoxic bacteria that are important to know we've got enterotoxic e coli. So this is spread in water and food that's been contaminated with feces is often very rapid and it's the most common type of traveler's diarrhea, as I've just said, Giardia or uh giardia. However, you say it is spread in contaminated water. So, lakes swimming, um it's got a longer incubation period. So often someone's come back from abroad and they've been swimming in some lakes and then they present with these symptoms. It might be more likely to be giardia. Um And often these can cause symptoms for 2 to 6 weeks with 1009 diarrhea. And often people can actually get a kind of lactose deficient uh lactose intolerance, post giardia infection. So that's also important to consider c diff, as I've said, if someone has had a very extensive antibiotic use or PPI use, that's proton pump inhibitors. So things like omeprazole, um then we might be more worried that they've got C diff. Um if they've got abdominal pain, if they've got watery diarrhea, um if you've ever been on the wards, actually, on placement, you can really smell C diff. I know that sounds, that sounds bad. But um there's definitely a specific smell to it. Um Often patients, if it goes unnoticed, they can present with a toxic me colon. So it's quite a serious uh medical emergency and the treatment for C diff is oral Vancomycin. Uh If you've done PT revision, you probably know the different stages if someone's got C diff and you treat them with oral Vancomycin, but it comes back within 12 weeks, we then treat them with something called oral famcin. However, if someone presents something like toxic colon or very, very um problematic C diff. So they might have uh pseudomembranous colitis, which is a complication, then we'd be treating them with oral Vancomycin as well as IV metroNIDAZOLE. So it's probably good to search up the guidelines for those. If you don't know them already. Um They do come up in password questions quite a bit. So that's good to know. Um We've got a staphylococcus aureus. We all know what this is. It's usually just food poisoning, quite a short incubation and it's more vomiting than, than diarrhea bacilla series. This is often caused when you reheat rice. Um, most people don't know that. But yeah, re reheating rice can actually be uh quite cause a, quite a serious infection. Again, very short incubation period and can cause vomiting as well. Some of the the viral infections that I've mentioned, norovirus and rotavirus. So rotavirus is actually the leading cause of severe diarrhea in infants. So that's why in the UK, we've got a vaccine for it. So at eight and 12 weeks, um they have a rotavirus oral vaccine, um which makes the disease milder. And in fact, the, the vomiting and diarrhea can be so bad that it can be fatal in some Children. So it's really important to recognize this norovirus is, you probably know you probably had it for a 24 to 48 hour vomiting and diarrhea bug. It's the most common cause of gastroenteritis in adults. Uh It causes these big breakouts in hospitals, cruises, uh schools, et cetera because when someone gets it, they might have, it might, you know, have an incubation period of 12 hours where they're in work or they're in school that they start vomiting in the evening or the next morning, but they've infected everyone, they've, they've met that day. So it's very highly contagious. Um and something to look out for. So the invasive bacteria again, this looks quite complicated. I think the ones important ones to know is, is salmonella and Campylobacter here. So, salmonella as most people know, uh is usually found in raw eggs or chicken. Uh it can cause abdominal pain, it can cause fever, it can cause diarrhea and it's usually got an incubation period of a day to a day, a day and a half. Um Campylobacter Judge knee. So as we've talked about the complications with Guillain Barre, um, it's the most common cause of gastroenteritis. Um, it kind of has this prodromal flu illness. So someone might feel quite unwell fluy feverish before they start developing these abdominal bloody diarrhea symptoms and it usually has an incubation of a couple of days. So, yeah, often after barbecues or things a couple of days after then this might be when someone's starting to feel bad. After that. We've got shla again, this has to do with contaminated water. So someone's swimming in lakes the same as Giardia. Um, it's got quite a long kind of incubation period. So it might be after someone comes back from holiday and then we've got uh vox E coli. So this is most common um in raw meat and raw veg. So there's been breakouts in things like Morrison salad bars not to put anyone off that. But, um, there's been things like that that I've seen, um, it's spread by people touching, you know, salad or meat or whatever and then obviously spreading it to everyone else. Um, however, a severe complication of it can be hemolytic ureic syndrome. So, again, important to understand that and understand the consequences of it. I think that's everything that I've got today. Yeah. So if anyone's got any questions, leave them in the chat for me, I hope that hasn't been too bad. I've tried to condense it um, into kind of the most key points there. Um So yeah, I think that's me done. Oh, I think we usually go for like a bit of a five minute break. So, uh we'll go for um uh around a 445 minute break and then we'll do um part two of case 15. So if everyone reconvenes for about um, 10 past and we'll start a case. Um Part two. Hi guys. So, um I'm Asher, then I'll be doing the second part of um case 15. So, um I'm hoping you guys can see my screen now. So, um we'll just get started with the second part. So, oh, so in this session, uh we'll ki kind of be covering the differences between um IBS and IBD. Um The common types of IBD S which are Crohn's and ulcerative colitis. We'll be looking a bit in celiac disease. We'll also be looking into some common genetic abnormalities associated uh with the lower GI. And then finally, we'll be looking at some X ray findings and um, some bowel obstructions and there should be some, um S va scattered throughout the presentation. So, um, for the first um, question, we have an SBA to start off. So we're doing, um, David, a 23 year old, uh, male presents to his GP with intermittent um, abdominal pain and loose stools. Um, the GP decides to order a stool sample and some blood tests. Um, the stool sample comes back as um, the fecal calprotectin is negative. Um H pylori also negative and blood tests, all of the inflammatory markers are uh normal and hemoglobin is within a normal range. So, what is the most likely diagnosis? Yeah, I think majority of you guys are getting it right. We'll just wait for, um, we'll give it another 10 seconds and then we'll um, stop the fall. All right. Perfect. So, um, the answer to this was d indeed, which is um irritable bowel syndrome. And this is because the i it's a young patient who's kind of come in with um intermittent abdominal pain. They come in with loose loose stools and like, um, thi this is quite a common presentation of irritable bowel syndrome. And the way to differentiate between IBS and an irritable bowel disease is the fact that none of the um inflammatory markers are high or abnormal in the blood. And also the fecal calprotectin is negative. So, in any IBD, whether that's Crohn's or ulcerative colitis, um we usually have um fecal calprotectin as positive. So that's usually a um big marker for in inflammatory bowel disease. And also because the H pylori test is negative, we're not suspecting anything like stomach ulcers or duodenal ulcers or anything like that. So, the most fitting answer um in this SBA is um irritable bowel syndrome, but we'll look a bit more into, um, IBS versus IBD now. So, essentially irritable bowel syndrome is, um, a funct kind of like a functional bowel disorder that results in symptoms like abdominal pain, abnormal, um, abnormal stools and, uh, abdominal discomfort. So things like, um, bloating, loose stools, um, constipation or you can have a mixture of both. Um, and often these symptoms have certain triggers. So they're usually like, they're usually triggered by certain foods like, um, like caffeine or like spicy, uh, or I increased spice or there are other triggers like stress and, um, this can lead to, um, IBS symptoms developing. So, symptoms are you get abdominal pain and discomfort which is often relieved on, um, passing stool and, um, you may also get, um, abnormal stool, so diarrhea or, um, or constipation or you might even get, um, uh, pr mucus. And in terms of investigations, we usually will look at inflammatory, we'll do a full blood count. Uh, we'll look at C RP, we'll look at E sr and if they're all in the normal range, and if fecal calprotectin is um negative, then we tend to suspect something like, um, irritable bowel syndrome rather than an inflammatory bowel disease. So, the to differentiate between that is that, um, there won't be any obvious signs of colitis or any obvious signs of inflammation without wi within the gut wall, um, which, which you can see with the blood markers and also the fact that um calprotectin is um negative. So, in terms of management of um IBS, we m uh majority of the time it's kind of broken out. It's a conservative and medical management. So in terms of conservative management, um you want to usually just decrease the triggers for um IBS. So that might be things like limiting caffeine, um reducing processed food, reducing like um spicy food and also things like lifestyle changes and stress management. So just to decrease the triggers of um IBS and in terms of medical treatment, you usually give um loperamide for kind of um acute onsets of diarrhea. So loperamide essentially um decreases the um amount of times that someone might have diarrhea and it's just more of like acute treatment that you would give for something that's not because of an infectious cause. So for something like IV and we also give um mebeverine um commonly prescribed and this um this, it essentially improves um gut motility and we give laxatives for constipation and in very, very severe cases of um IBS, sometimes SSRI S and tri cyclic antidepressants are also prescribed. But this is usually very much, it's like kind of like I, if the IBS is really, really bad, then um Sr SSRI S and tri tricyclic antidepressants are prescribed. So how do you differentiate between, um, kind of like IBS and IBD? So IBD is um, a disease that causes inflammation within the gi tract. And essentially, it's kind of an umbrella term for two types of conditions. And those two conditions are Crohn's and ulcerative colitis. We'll look a bit more into that. But um it's u it's essentially an inflammation or um dysfunction of the gi tract. So we have um another SBA so a 27 year old, um 27 year old woman possessed to a GP with symptoms of abdominal discomfort. Over several months, they have experienced bloody diarrhea, se uh um severe abdominal pain and discomfort and she has not had any recent travel history and has been following her, her diet in terms of her bloods. Um her uh C RP is quite high and her fecal calprotectin is also uh positive. She has, she has had a colonoscopy and her histology shows that she has a depletion of goblet cells and presence of pseudopolyps. So which, what is her most likely diagnosis? We've got a variety of answers. So we'll give a bit longer on the poll and more seconds. Ok. So majority of you guys did get this answer, right, which is the answer was c which is ulcerative colitis. So, in this presentation, um the key way to differentiate and kind of decide upon which type of um which type of um IBD is, is within the symptoms that they are presenting with and also with the histology. So in terms of um symptoms, ulcerative colitis is usually quite unique for um things like bloody diarrhea and it uh it will, I will go into more detail about this, but it, it usually affects kind of the rectum and the sigmoid colon. And um you know, you have ulcerations within that region which can cause you to have bloody diarrhea. And also in terms of um in terms of histology and biopsy, you usually tend to see depletion of um goblet cells. So like decreased mucus. Um and you also have like present uh presence of pseudopolyps. So we'll go uh more into detail about this in the next slides. So we'll start off with the first type of IBD, which is Crohn's. So, in terms of Crohn's, um in terms of the pathophysiology of it, it is an um inflammatory condition of the gi tract, um which kind of results from recruitment of CD four th 18 and natural killer cells. You don't necessarily need to know um kind of what like the in depth about the pathophysiology about it. The main thing you need to know about Crohn's is the fact that it is a condition that affects anywhere between the mouth and the anus. So it can, um it's kind of like um inflammation that can affect anywhere between the mouth and the anus. So it's kind of um throughout rather than um ulcerative colitis, which is kind of um in a specific area. So in terms of um common presentation, it's common in younger um adults. So any type of IVD is um usually it presents at quite a younger age. Um and you present with nonbloody, uh watery diarrhea and you, you can also present with mouth sores and mouth ulcers. And it, it is also um seem to affect kind of the right iliac fossa region in terms of pain and um tenderness as well when we look at kind of the clinical relevance. Um One thing I would like I would say um to remember is the fact that um smoking has an effect on ulcerative colitis and Crohn's. So usually if we look at the apology of um and Crohn's um s smoking is protective um against ulcerative colitis and usually um Crohn's um in Crohn's smoking makes um ulcerative colitis worse. So, obviously, you know, from a clinical perspective, we wouldn't recommend people to um smoke, for example, to make the ulcerative colitis better. But in preexisting um smokers, it almost has a therapeutic effect rather. Uh whereas in um Crohn's, um it makes it worse. Now, if you look at kind of um the IMA imaging and histology of it. So specifically in um in Crohn's, you get transmural inflammation. So what that essentially means that you have inflammation within all of the layers. So all of like the mucosa, the submucosa, all of the regions you get um inflammation throughout and you also get kind of as you can see in the second pictures, you get presence of um granulomas. So granulomas are essentially like clusters of immune cells and you can get caseating and non caseating granulomas. So, um caseating are kind of like um cluster of cells that have like that that are undergoing necrosis and non caseating are granulomas that are not undergoing necrosis. So, in um particularly in um in Crohn's, you see um noncaseating granulomas and you also may see like um skip lesions um throughout and once again, in terms of um in terms of the inflammation, it can happen anywhere in the gi tract. Whereas um in ulcerative colitis, it's kind of in a specific area which is the um sigmoid colon and the rectum region in terms of also like extraintestinal manifestations. Um because IBD S have been linked with um autoimmune causes, it is also linked with other conditions. So some these conditions do sometimes come up in um in, in exams like PT S and um in, in, in, in S two S where um it can ask you for the extraintestinal manifestations. So for Crohn's, um you have a high chance of developing peripheral arthritis, um um eryth, not no um and pyma ganglion. So essentially like um skin issues as well as arthritis, which is um obviously inflammation of the joints. So, in terms of the pathophysiology of um ulcerative colitis, like we said before, um inflammation and kind of the progression starts from the rectum and doesn't progress part of the ileocecal valve. So it's essentially kind of limited to a specific area which is your sigmoid colon and of your rectum. And once again, it has an involvement of natural killer cells and um CD four cells in terms of presentation, how it differs from Crohn's is that in Crohn's, we got um kind of abdominal discomfort and uh watery diarrhea. Whereas in um ulcerative colitis as you have ulcerations kind of um forming in the um sigmoid colon region and in the rectum, you get a higher chance of having bloody diarrhea. So usually if you see um uh a presentation with who with a young patient who's had um intermittent bloody diarrhea over a long period of time, um has experiencing say weight loss, fatigue and just general um abdominal discomfort, like presentation wise, it is indicative of um ulcerative colitis. So, um for like the kind of the clinical relevance of this part, one thing to remember about ulcerative colitis is that um I think Mia uh mentioned this slightly um before is the fact that the most kind of severe complication of ulcerative colitis is the formation of a toxic mega colon. So essentially this is um kind of like a um an obstruction of the gi tract. And um it can, it can be as a result of severe um ulcerative colitis flare ups and also ulcerative colitis has been associated with a higher chance of developing um colorectal cancer. Usually IBD because it's an inflammatory condition. Has a ha um has been linked with um inflammation which is one of the hallmarks of developing um cancer. So, like we said before, uh wearing the gi a gi track, it usually affects the rectum and the sigmoid colon. So in, in terms of the imaging and histology of it, um you, you kind of get the depletion of goblet cells um in the um histology region, you get presence of pseudopolyps and then you might also in um in like colonoscopy, um imaging, you'll see singular or multiple um ulcerations within the gi tract. Um and obviously presence of um bleeding as well in the gi tract in terms of um extraintestinal manifestation. Um some of the common conditions associated with ulcerative colitis are arthritis, um uveitis and also pri primary sclerosing cholangitis. So this is sometimes a question that's quite asked commonly on um like PT style questions that um often a patient who has a history of um ulcerative colitis may come in with um kind of um deranged um liver function tests. And usually if you see UC, then um an extraintestinal manifestation or, or, or a complication of UC is that they have a chance of um developing a type of cholangitis, which is um primary sclerosing cholangitis. So, in terms of management of um Crohn's in, so for Crohn's, we usually start off with um smoking cessation if the patient is a um is a smoker. And this is kind of part of like the conservative slash lifestyle uh modifications and in terms of medication, um steroids are given and um u usually the uh the, the most common choice of drug that is given is um ii can't really pronounce it probably, but it's Azath. And um if, if Crohn's isn't managed um with medication over um a long period of time and if they have um signs of um long term colitis and complications, um such as things like um fistula formation or, um you know, if it's affecting their um day to day lives um significantly, then there, there is a surgical option of resecting the distal um ileum um to help with symptom management and um some of the induction of like stromas and in terms of the management of um ulcerative colitis. So it's kind of um it's kind of broken down into mild, moderate and also like flare ups. So for um m mild to moderate ulcerative colitis, usually topical um im immuno salicate are given and um for severe um flare ups, usually, um IV corticosteroids are um the treatment choice. So if some, if a patient comes in with um, a fever and they go, they're having um, stools up to 89 times a day. And, you know, it's, they're, they're experiencing bloody diarrhea, you are up to 89 times a day with temperature and the observations are off. Um, usually kind of first line treatment tends to be um IV corticosteroid. And once again, in terms of surgical options, um do sometimes things like permanent ileostomies and ilio um ileostomies are offered and also sometimes um ileoanal anastomosis are also offered. So these are kind of like long term um um treatment plans for osteitis and Crohn's. Um OK. So that's kind of as done with diabetes in terms of ulcerative colitis and um Crohn's. So we have one more um SBA which is um a 21 year old female comes in um to the GP with bloating, abdominal discomfort and weight loss. Blood shows normocytic a uh anemia and an anti T uh T EG A and IG A is positive. So, um an endoscopy is conducted. What will the biopsy be of this show? Ok. So um majority of you guys kinda went for um celiac disease, which technically is right? But in terms of like the best um kind of uh suited answer for this, I would have gone for uh villous atrophy because we're specifically asking for what the biopsy will show. So, um villous ay is indicative of celiac disease usually. But um the question, the question wasn't necessarily what is the um diagnosis. It's more so about like what the biopsy will show we'll go into more details on um celiac disease. Next. So in terms of pathophysiology of um celiac disease, so it is once again, inflammation of the small bowel. And um this has been linked to antibodies like anti PT um G and anti TMA and it leads to epithelial cell destruction and bili atrophy. And this can lead to um decreased kind of absorption within the gut wall. So um in terms of like biopsies, you will usually see um you will usu usually see like um atrophy of the vla and also um destruction of the epithelial cells that are present in terms of clinical features. So, uh patients almost kind of uh present with diarrhea, nausea, vomiting, fatigue, uh macrocytic anemia and um and also like kind of failure to thrive in Children as well. So, um usually for diagnosis of um celiac, we measure anti TG levels and IG levels. And um also we do um like uh we do biopsies, which is usually the gold standard eve investigation choice. And you can usually see like we mentioned before villous atrophy and also um cell d um epithelial cell destruction. Um The uh also any other associated conditions with um with celiac is kind of associated with, with the genes involved. So, um celiac has also been um associated with things like type one diabetes thyroid dysfunction and autoimmune um hepatitis because of um the genes that it's involved with. And also because it is um an autoimmune condition. So we'll just go into um kind of some genetic conditions that are associated with the gi tract. Now, so once again, we have another um SBA so a 38 year old male comes into the GP and he is very depress dis uh distressed about developing bowel cancer. He mentions that many of his family members have had a genetic condition which severely increases their chances of developing bowel cancer. He states that it is caused due to mutations in mismatch repair genes like M HL one and MS H two genes. What condition is he referring to? We could launch the pole. OK. We have a bit of a split between A and C. So I'll give it a few more seconds before we kind of go into the common genetic conditions um associated with the C. OK. So um the correct answer in this situation was um C which is Lynch Syndrome. And um I'll, I'll explain more into why cause we the two conditions that you have to be um aware of in um in terms of like genetic conditions affecting the lower GI is F AP and Lynch Syndrome. So F AP is um kind of familial adenomatous polyps, cysts. So essentially this what this is is it's an autosomal dominant condition and um it's caused by mutations in the a PC gene. So uh because of this mutation, you kind of get um you kind of get active activation of oncogenes which can um result in um the formation of um cancer. And you can also get kind of um the formation of multiple polyps in the large intestines. And um once again, this uh this increases your chance of developing uh bowel cancer. And usually screening is offered to patients and um colonoscopy. And um yearly screening is kind of the um choice of um uh choice of prevent prevention slash kind of monitoring of um F AP. And in terms of Lynch Syndrome, which is what the last question was associated with it is once again another an autosomal dominant condition. However, um the thing to remember with Lynch Syndrome is it is the condition that's most associated with um the highest chance of um genetic predisposition to colorectal cancer. And how it differentiates with F AP is the fact that it causes mutations in mismatch repair genes. So, genes um like mmmh L1 MSH two MSH six and PMS two are mismatch repair genes and mutations in these genes can um um significantly increase your chances of um inflammation and developing colorectal cancer. So, um how to do so the two conditions to remember are F AP and um Lynch Syndrome. So kind of um with F AP, the way I remember it is F AP has AP in it and it affects the A PC gene, whereas um uh it w which is more of like a tumor suppressor, whereas um Lynch syndrome affects um kind of uh mismatch repair genes. You don't necessarily need to know the names of um all of the genes that are involved, but sometimes they do come up in um question. So the key thing to remember with that, in my opinion would just be the mismatch repair genes. And the fact that with Lynch syndrome, it usually um has the highest chance of developing um colorectal cancer. And usually with uh with patients who have um Lynch syndrome in the family, they are given yearly screening and a regular screening um to um increase kind of their prognosis and decrease chances of um delay diagnosis. So next thing that we're going to be looking at is um bowel obstruction. So we'll kind of be looking at short bowel obstruction and large bowel obstruction. So, um uh first we'll look at the causes of short bowel obstruction and large bowel obstruction. So usually for um short bowel, um some of the causes include things like adhesions, hernias and um inflammatory bowel diseases like Crohn's disease where worse for things like um large bowel obstructions. Some, sometimes it causes uh things like volvulus formation. Um kind of formations of out like cause like for formation of like out pouching that can be as a result of conditions like diverticulitis or um kind of um all kind of conditions like uh colorectal cancer that can lead to an obstruction within that region of the um gi tract. Um in terms of some clinical relevance here, one thing to remember with uh bowel obstructions is the normal diameters of the bowel. So usually the thing to remember here is the rule of 369. So the small bowel norm, normally the diameter of that is around three centimeters. And for the colon, it's around six centimeters and for the c it's around nine centimeters. So if you see any sort of like dilation above those numbers in those specific regions, and you, uh, a patient presents with, um, things like, um, um, abdominal discomfort, nausea, nausea, vomiting, um, inability to pass stool or, um, uh, pass, um, any sort of, um, um, gas, then you, you are, I'm suspecting something like a bowel obstruction. So I would definitely recommend remembering the normal damages of the bowel. And, um, the fact that in anything above this can be an indication of bowel obstruction. So, if we look at, um, kind of, um, ma investigation and management of bowel obstructions. So, a typical presentation like we mentioned before is that patient might present with, um, abdominal distension. So, um, failure to pass bowels or flats, nausea, vomiting, um, um, abdominal discomfort and it is quite, um, it, it is often more, um, seen in elderly patients and in terms of, um, investigations kind of the gold standard investigation used for, um, bowel obstructions is, um, an abdominal x-ray will usually show distended, uh, bowel loops and, um, you can usually differentiate between a short bowel or a large bowel, um, obstruction from the x-ray itself. And, um, in terms of the management of bowel obstructions, usually the patient should be given IV fluids and, uh, the treatment of choice is kind of surgical intervention. So to you want to, so the long, so the curative slash long term treatment is surgical intervention to correct the obstruction itself. And, um, usually you also want, um, in, um, in elderly patients or with, um, anyone presenting with bowel obstructions, you also want to remember the insertion of a nasogastric tube as you know, they're not because there's an obstruction in the gi tract, they're not really able to, um, necessarily like digest any of their food. So, um, the three things to remember is you wanna give them IV fluids, you want to insert an NG tube and you also want to, um, um, kind of refer them to, um, gi surgery to treat the obstruction itself. So, in terms of X ray findings between a short bowel obstruction and a large bowel obstruction in a short bowel obstruction, you kind of get dilation of the bowel, which is above, um, three centimeters. And usually, um, you have these normal kind of folds which look like coils within the, um, short bowel, um, called valvulae. I can't really pronounce the second word, but, um, it, but usually with bowel obstructions, what you get is you get more prominent, um, more prominent coiling of this area and you get more prominent dilation. And um in terms of large bowel dilations, you usually get a kind of prominent um dilation in the periphery. So the short bowel, we're looking, it's more central and with um, large bowel looking at the peripheries and it, the dilation is once again above six centimeters. And some people also refer to this kind of a like little coffee bean, um, appearances that you can see in the x rays that are provided as well. So, um the key thing to remember once again are the normal numbers and the fact that if you can see um an increase in dilation, um you are suspecting something like an obstruction. So we'll look a bit into uh abdominal x-rays in general. So, um, so usually indications for conducting an abdominal um x-ray are things like um evidence for bowel obstruction. So, if a patient presents with the symptoms that we spoke about, um, then we might want to do um an x-ray as a diagnostic kind of test. Um If we can see any evidence of things like bowel perforation, or um if the patient has any kind of um conditions like um other background of things like diverticulitis because that can kind of cause out pouching um of the um of parts of the gi tract and that can result in kind of um a section of the bowel perforating, um and can be a medical emergency as well. So, if you see a background of um di conditions like diverticulitis and the patients, you know, presenting with like acute abdominal pain, you might want to consider something like an abdominal x-ray in terms of um, like we mentioned. So normally in kind of normal um scenarios, um the the short bowel uh lies more centrally and um, the large bowels um lies more um distally and you can kind of see, um, these kinda fold slash um slash coiling um in the, in the um short bowel. And you can also, um, in the large bowel kind of, um, see pouches in, in the lumen of the, the, the bowel, um these are called Haustra. So if in a question, um they, they, they mention these two words and they're, they're quite easy to differentiate between whether we're looking at the large bowel or we're looking at the short bowel. Um, in terms of kind of the effects of IBD um on kind of the gi tract. Some of the um, things that we to look at, like we mentioned are things like um toxic omega colon. So, so that is usually kind of the chronic dilation of the bowels and it can lead to um severe bowel um bowel obstruction and is one of the most fatal complications of um, ulcerative colitis. Um, in terms of another condition, sometimes you also may see some um thumb printing and this can be due to kind of chronic in um inflammation secondary to IBD. So, one of the signs of um an IBD on an abdominal x ray is this kind of thumb print printing appearance that you can see uh which you can see in the um the second picture and rarely sometimes in abdominal x rays, you can see certain malignant masses but usually ct abdomen and pelvis is kind of the gold standard for um looking for malignancies within the um gi tract. But um or, or things like colonoscopy or um endoscopy, endoscopies, but sometimes you can see uh malignancies uh on x rays as well. So I think that's all from me for uh today. Uh Please don't uh forget to fill out the feedback form. I think it should be put in the chart. Yep. And then you should, you guys should be getting slides and also like Ryan mentioned before, do look out for your, for our conference that's coming up soon. Um It's a really, really good opportunity to kind of get um tips and tricks as to how to get um you know, things like publications and kind of look at uh future long term um ideas on how to build your portfolio. And also it's a great opportunity to kind of network with other medics as well. So do look out for that and um I think that's all for me for tomorrow, uh for today guys. Thank you.