Speaker A
So in this video, we're going to look at IBD, which is inflammatory bowel disease, a chronic inflammatory bowel disease which pursues a protracted relapsing and remitting course. There are two types of IBDs, and let us look at them now. So IBD typically involves the colon, but of course, one of the types of IBD involves the whole GI tract. Now, the two types of IBD are ulcerative colitis and Crohn's disease. When talking about ulcerative colitis, it mainly presents with inflammation of the rectal and sigmoid colon, about 40 to 50 percent, and this is referred to as proctitis. Now, comparing that to Crohn's disease, in Crohn's disease, the main area affected is the cecum and the ileum, the ileocecal area. Forty percent of Crohn's cases involve the ileal and ileocolonic area. The second-most common area affecting Crohn's is the small intestine, about 30 to 40 percent of cases, and in the small intestine, we see the inflammation in segments. This is termed skip lesions because you have inflammation and then you have no inflammation, and then inflammation again, and no inflammation, etc. Some people who have Crohn's can have skip lesions in the colon, the large intestine. Twenty percent of Crohn's disease cases have this, and this is referred to as Crohn's colitis. And finally, a small majority of cases have perianal inflammation. So those were the four most common areas affected in Crohn's disease, and as we've learned, a typical characteristic of Crohn's disease are the skip lesions. Going back to ulcerative colitis, the main areas affected, as we talked about, is the rectal sigmoid area, and this is termed proctitis. Well, a characteristic of ulcerative colitis is that the inflammation can spread, and it spreads approximately from the rectal sigmoid area up the descending colon. Thirty to forty percent of ulcerative colitis cases have this, and this is termed left-sided colitis. If the inflammation spreads far enough that it reaches the transverse colon, this is known as extensive colitis. So we just saw the common areas affected in ulcerative colitis and Crohn's disease, and we saw that they had some differences in that ulcerative colitis spreads distal to proximal, and Crohn's disease has skip lesions and mainly affects the ileocecal area, but there are a lot more differences which we will go over later on. But first, let us look at the signs and symptoms associated with inflammatory bowel disease. So signs and symptoms of inflammatory bowel disease can include, but not always, diarrhea, rectal bleeding, abdominal pain, tenesmus, fever, weight loss, vomiting, cramps, and muscle spasms. Let us look more at the differences now and similarities between the two types of inflammatory bowel disease. So we will look at the differences in gender incidence, smoking association, the onset, location, pathology, histological differences, as well as complications. So in ulcerative colitis, both genders are affected in the same ratio, whereas in Crohn's, they affect more females than males. Incidence of ulcerative colitis and Crohn's disease are similar, except there are more cases of Crohn's disease, no spur year two point one to twenty per 100,000. Smoking is very interesting for inflammatory bowel disease because for ulcerative colitis, smoking is actually a protective factor, whereas if you smoke in Crohn's, this actually aggravates the condition. The onset of ulcerative colitis and Crohn's are roughly the same. The location, which we talked about earlier, for ulcerative colitis is mainly the distal colon, the rectum, and sigmoid area, remember, and for Crohn's, it's the distal ileum and cecum, but it can also affect other areas along the GI tract. Now, let's talk about the pathology differences. So for ulcerative colitis, it is a continuous inflammatory lesion that progresses, that it basically progresses from the distal colon to the proximal colon. Now, whereas in Crohn's, it is typically discontinuous patchy gut inflammation with skip lesions. Histologically, ulcerative colitis is a superficial inflammation, whereas Crohn's disease is a transmural inflammation, which means that it actually goes through all the layers of the colon. Complications of ulcerative colitis include severe bleeding, toxic megacolon, rupture of bowel, as well as colon cancer. For Crohn's disease, complications are more severe because histologically it affects all the layers of the GI tract, transmural inflammation. So therefore, complications include stenosis, abscess formation, fistula, colon cancer, as well as perforation. Okay, now let's put all this into drawing. Let us first zoom into the ulcerative colitis-affected colon here. So here is the inflammation of the large intestine, the superficial inflammation, remember, ulcerative colitis changes as in relapsing and remitting. When the disease is active, it causes ulceration and inflammation. When inactive, the cells are basically dying; you get atrophy of cells following the inflammatory reaction. In ulcerative colitis, you can get complications such as severe bleeding, toxic megacolon, rupture of the bowel, and colon cancer. Now, if we were to take a section of the large intestine, we have the histological layers, of course, the muscularis, the submucosa, the mucosa, and you can also have these things called pseudopolyps, which is a characteristic feature of ulcerative colitis. Pseudopolyps arise because the cells of the colon are trying to regenerate, but they regenerate weirdly, causing these polyps as a result. Now, let us compare ulcerative colitis to Crohn's disease. In Crohn's disease, it can affect the large intestine or the small intestine. Let us zoom into the small intestine there. Here, within the small intestine, you see transmural inflammation with skip lesions. Complications of Crohn's disease include stenosis, abscess formation, fistula, colon cancer, as well as granulomas. If we were to take a cross-section of the small intestine, here is the mesentery, the muscularis, the submucosa, and the mucosa. We can see in Crohn's disease, all the layers are affected; it is a transmural inflammation. And so complications of Crohn's disease can be quite serious in that it can lead to perforation, fistula, etc. And in the next video, we will look more actually at the pathophysiology of inflammatory bowel disease, as well as look at the complications, the local as well as systemic, and the investigations and management that can be performed for inflammatory bowel disease. Thank you.
