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Inflammatory bowel disease vs irritable bowel syndrome

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Matthew McPheeters.

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Video transcript

- [Voiceover] Let me introduce you to Frank. Now, for most of the last year, Frank's digestive system, it's just not been feeling quite right. He's been having intermittent, although fairly frequent abdominal pain as well as irregular bowel movements. And at times he's not able to have a bowel movement. Then at other times he's been having them very frequently. And he was telling a close friend about these symptoms. And his friend said, you know, Frank, I was watching something on TV, and I heard about this condition. I'm not exactly sure, but I think it was called something like irritable bowel disease. And it sounds somewhat similar to what you're experiencing. Perhaps you should go see a doctor. So Frank goes to see his doctor. And he says, you know, doc, I think I have IBD. And Frank's doctor says, you know, I'm sorry to hear that. Please tell me why you think you may have IBD. And as he's relating these symptoms to her, she thinks to herself, you know, I wonder if he means IBS instead of IBD. And so his doctor responds, Frank, you know, I'm concerned you may have a condition known as irritable bowel syndrome, which is commonly referred to as IBS. And Frank says, isn't that IBD? And his doctor replies, that's a common mistake. Unfortunately, there are two different conditions with very similar acronyms. They are irritable bowel syndrome or IBS and inflammatory bowel disease or IBD. Let's learn about the differences between IBS and IBD. So let's start on the left here with irritable bowel syndrome or as it's more commonly referred to, IBS. But what exactly is a syndrome? To help get a better idea, let's think about a car. Now, imagine that something is just not quite right with your car. So you take it into the auto shop. And you tell the mechanic, you know, there's this rattling sound under the hood. And the car has poor acceleration, and the check engine light is on. So the mechanic says, you know, it sounds like it may be car engine rattling syndrome. And that can be caused by many different things. It could be a loose part in the engine, a loose fan belt, or perhaps even low oil. Now, car engine rattling syndrome may not be a real thing, but it demonstrates the idea that a syndrome is not defined by the underlying cause of the problems. There's multiple different causes for this one syndrome, but instead by the sounds and effects that it has on the car. Similarly in medicine, syndromes are conditions that are defined by a set of clinical signs and symptoms and not necessarily by their underlying pathologic mechanisms. In fact, most syndromes can be caused by multiple different mechanisms that end up having the same presentation. So irritable bowel syndrome is a condition that's defined by a specific set of signs and symptoms, which we will discuss in just a moment. Now, this is different from inflammatory bowel disease or IBD. So inflammatory bowel disease is not a syndrome. It is a group of two disorders that occur due to a known mechanism, specifically inflammation. And these disorders are Crohn's disease and ulcerative colitis. So what are the differences between the two? Well, for irritable bowel syndrome, the diagnosis is made clinically based on the frequency and duration of symptoms, specifically recurrent abdominal pain or discomfort at least three days per month for at least three of the last six months plus two or more of the following, pain that is improved with the bowel movement or the onset of pain is associated with the change in bowel movement frequency, such as constipation or diarrhea. And lastly, the onset of the pain is associated with a change in the form of the stool. So these are the symptoms Frank was experiencing. Now, the cause or pathologic mechanism of IBS is unknown. And this is part of the reason why it's classified as a syndrome. Now, similar to IBS, the exact cause of inflammatory bowel disease is not well understood. However, the underlying pathologic mechanisms that result in Crohn's disease and ulcerative colitis are known and can be identified. So in both of these diseases there is an inappropriate inflammatory response. And this occurs within different portions of the digestive tract. And it results in identifiable and observable pathologic intestinal damage. And it's these pathologic changes that are necessary to make the diagnosis of inflammatory bowel disease. Now, for ulcerative colitis, the damage is contained within the large intestine, whereas with Crohn's disease the damage can occur anywhere throughout the GI tract, really. It can occur anywhere from the mouth to anus. Let's briefly discuss some of the differences between irritable bowel syndrome and inflammatory bowel disease in regards to treatment. And we're gonna break these treatments into two groups, which we'll call symptom focused and mechanism focused. Since both the irritable bowel syndrome and inflammatory bowel disease have similar symptoms, many of the symptoms focused treatments will be beneficial for both conditions. And these include things like diet and lifestyle modifications, such as a high fiber diet and routine physical exercise, as well as medications that speed up or slow down the intestines. And that depends on which symptoms are present. So if there's diarrhea, then you can use anti-diarrheal medications. And if there's constipation, then you can use laxatives. Now, since the mechanisms in IBS and IBD differ, the mechanism focused treatments will also differ. So although the exact mechanism of IBS is not well understood, it can be thought of as anxiety of the gut. And therefore, it responds to similar therapies as anxiety, including cognitive behavioral therapy or CBT and anti-anxiety medications, such as SSRIs. Now, in regards to IBD, as its name suggests, inflammatory bowel disease is due to an inappropriate inflammatory response. Therefore, medications that decrease inflammation, known as anti-inflammatory medications, such as steroids, and medications that change how the immune system and the inflammatory cells act, known as immunomodulators, can be used to decrease and prevent the inflammation that ends up causing inflammatory bowel disease. So this has just been a brief overview of the difference between irritable bowel syndrome, a disease that's defined by its clinical presentation, and inflammatory bowel disease, which is defined by the underlying pathologic mechanisms.