The last two lectures that we have for the morning, it's scheduled for talking about diseases of the lower GI tract, so the large bowel. So I'm going to try and go through this section pretty quickly, and then my thoughts are just because we are running a little bit behind, we'll take a break, we'll grab some lunch, do the Bioskills Lab, and then we'll finish up with inflammatory bowel disease and IBS at the end. Okay. Okay, so we've already talked a little bit about colorectal cancer, but we're talking about cancer that involves anywhere in the colon or the rectum. It is one of the most common cancers in the United States, so when you combine men and women together, it's the second leading cause of cancer death, and the lifetime risk is actually 5%. Now, if I was giving this talk maybe 10 years ago, we'd be talking about colon cancer screening prevention as kind of a triumph because we have seen significantly lower rates overall of colon cancer diagnosis because we're so effective at screening. As we did discuss earlier, unfortunately, we are seeing rising rates of colon cancer development in younger and younger people. It's multifactorial, most likely related to things such as diet, obesity, the quality of our foods, ultra-processed foods, a lot of other factors there. And the data is changing in terms of how we can effectively screen younger patients who seem to be at higher risk. Now we also went over this slide previously, so we'll kind of breeze through this, but essentially the purpose of doing a screening colonoscopy is to find these little polyps when they're small. So polyps are just little bumps on the inside of the colon that have started to develop mutations. So the cells have started to develop mutations that tell them to grow. And so if they grow over time and over time, they become dysplastic, meaning precancerous, and then adenocarcinoma is basically a cancer. Now I always tell patients is that polyps grow very slowly. So from a small polyp to become a cancer, yes, it does take at least 10, 15 years. Sometimes if you have certain genetic conditions, that process can be accelerated. That's why we usually recommend if you don't have any polyps to do a colonoscopy every 10 years, because then we'll definitely catch any small polyps before they even have a chance of becoming a cancer. Now colon cancer can present in varied ways. Oftentimes these days patients are totally asymptomatic and we diagnose it on screening. But some patients can present with suspicious signs and symptoms, one of the most common being anemia. So these tumors, if they're growing inside the colon, can start to bleed and ooze. Sometimes they bleed fast enough that the patient will see it. So rectal bleeding is one of the biggest red flag symptoms that we tell patients to see your doctor immediately. And it unfortunately, if colon cancer has progressed to the point where it's causing a blockage, then patients can present with a large bowel obstruction, which is similar to the small bowel obstructions we heard about earlier today, and peritonitis, which is basically If the tumor penetrates through the colon wall and bursts, that can basically cause a perforation that causes infection within the abdominal cavity. Now screening, as we talked about earlier, we used to recommend starting screening at age 50. We now recommend everyone over the age of 45 get screening. Now these recommendations can change depending on a patient's family history, if they have a genetic syndrome that increases your risk of colon cancer, or other conditions such as inflammatory bowel disease. Now there are many different screening modalities available. And we had these two highlighted, but actually probably could update this in terms of the most frequently used. So historically, we would use what's called a GWIAC or a fecal occult blood test, which basically just measures for microscopic amounts of blood in the stool before a patient would even notice it. The more advanced version of that is a fecal immunohistochemical test or FIT test. Now if you choose to do a FIT test as your screening modality to forego a colonoscopy, you have to do a FIT test every year, basically to check for microscopic blood on the stool. And if at any point, if that FIT test is positive, then you need to have a colonoscopy. Now in recent years, there's also been the release of these multi-targeted stool DNA tests. The most commonly used in the United States is Colagard. Now if we do that test, it's checking for both microscopic blood and also DNA that tends to be shed by polyps and cancers. If you choose to do a Colagard test, you need to do that every three years. And again, if at any point that Colagard test is positive, you then need a colonoscopy. Now alternative screening modalities that are used in other parts of the world include flexible sigmoidoscopy. That's kind of like a mini colonoscopy where you're only looking at the last 20 to 30 centimeters of the colon. Oftentimes that's done in combination with a FIT test. If you're doing a flexible sigmoidoscopy in combination with a FIT test, you'd be doing your screening every five years. That's more common where I'm from, which is in Canada. Now colonoscopy, as we've discussed, is not only a screening procedure. It's also therapeutic. We can truly prevent cancer by being able to remove the polyps at the same time as the procedure. And CT colonography or virtual colonography is essentially doing a CT scan where it kind of looks at the lining of the colon to see if there's any irregularities that could be consistent with polyps. Some patients do opt to do this rather than colonoscopies. However, unfortunately, again, it's not a therapeutic or preventative procedure. If any polyps are seen, you're still going to need a colonoscopy afterwards. Now colon cancer, these are several endoscopic images that are examples. And essentially, even to an untrained eye, you can see that these photos just look very ugly. There's a mass. Some areas have some ulceration. You can imagine that these could be bleeding. And if it grows larger and larger, it can start to actually block the intestinal, the lumen or the tube of the intestine. Now treatment, the one thing about cancer or colon cancer and cancers in general is that if you can find it when it's still early and it hasn't spread elsewhere in the body, it can often be treated with surgery. And that's always our hope whenever we find these things. So for example, in this photo, if you have a cancer that's in the sigmoid colon or the left side of the colon and you do scans and you make sure that the tumor has not spread elsewhere in the body, you can actually just do surgery just to cut out that part of the colon. And here on the right side, they're showing what's called a primary anastomosis, which is essentially they just cut that part out and they hook you back up together. There's no colostomy bag. You just go about your life. And hopefully that's curative for you. Now that's what we always hope in stage one cancer is that's what we hope when we diagnose it. However, if the tumor has started to spread elsewhere in the body, then unfortunately surgery may not be an option and may not be an option in the beginning. You think about things like chemotherapy, also radiation therapy to help shrink the tumor. And it's really advanced palliative care as well too. Now lower GI bleeding kind of touched on this a little bit previously when we were talking about upper GI bleeding. However, lower GI bleeding basically comprises anything, any bleeding source below the ligament of trice. Usually that bleeding is coming from the colon. However, you can also have bleeding that's coming from the upper GI tract or small intestine as well too. Now the symptoms. So traditionally we think about lower GI bleeding as being hematochezia, which is the medical term to describe frank bright red blood coming from the rectum. Melanin is altered blood that's kind of dark. It almost looks dark black. It almost looks like fresh tar that's been poured on a road. Now yes, traditionally we think of hematochezia as coming from the lower GI tract or the colon. However, that can also come from the upper GI tract as we discussed. And melanin usually comes from the upper GI tract, but it can also come from earlier parts of the colon as well too. Now if you're not having bleeding, you can also just have, or in addition to the bleeding, you can also be having symptoms from just having low blood counts or anemia. So if it's really severe, you can start to feel lightheaded, syncopal, meaning feeling faint, having shortness of breath, chest pain. Now what are causes of lower GI bleeding? So diverticulosis is one of the most common causes. Diverticulosis here is when you see these little pockets or holes in the colon. Those develop over time with age or with poor diet. And basically if they continue to grow and grow, those holes can basically start to penetrate through an artery, which causes bleeding. You can also have vascular bleeding from angioectasias like we've talked about previously. Something called ischemic colitis, which is essentially where part of, similar to mesenteric ischemia that we were talking about before. However, this is decreased blood flow to the colon that can cause ulceration and bleeding. Hemorrhoids can bleed. They seem like just kind of a common, benign thing, which they are. However, they can bleed quite aggressively as well too. Colon cancer, as we discussed. And then we'll go into later inflammatory bowel disease, infectious colitis. And also, fortunately, we can have what we call iatrogenic causes or things that we cause to the patient. So for example, if you cut off polyps using cautery like we talked about earlier, the reason why we usually try and put hemoclips on them to close off the areas that they can bleed afterwards. They can bleed quite briskly. So how do we treat lower GI bleeding? So we always teach all of our medical students they need to start two large bore IVs. And what that essentially means is that you want to place IVs that are of the largest size or caliber. So if you think about physics, the larger the diameter of the catheter, the faster you can infuse fluids and blood products. Volume resuscitation refers to both fluids as well as blood products, if necessary, like blood transfusions. Now how do we manage someone who comes into the emergency room and you're suspecting they could have lower GI bleeding? So the most important thing is to make sure you're not dealing with an upper GI bleed. The reason why this is so important is because upper GI bleeding is actually generally causes more instability than lower GI bleeding. You can be bleeding quite a bit, quite profusely from something like a diverticular bleed, be filling up toilet bowl after toilet bowl full of blood, but you'll still be pretty stable. Your blood pressure is fine. You don't need a blood transfusion. On the other hand, if you're pouring out blood and it's coming from an ulcer higher up in the GI tract, let's say a stomach ulcer, those patients tend to be very unstable, often need intensive care unit care as well, too. So it's very important to make sure you're not dealing with a brisk upper GI bleed before you start focusing on the colon. Now historically, we do something called a nasogastric lavage, where you put an NG tube in through the nose and sit in the stomach, then you basically flush it to see if any blood comes out of the tube. Now we stop doing that for the most part just because it's not entirely accurate. You can definitely miss things if you don't do the flushing appropriately. And also because most hospitals do have access to upper endoscopy, you can do that pretty quickly and safely. So if we are suspecting that a patient could have a brisk upper GI bleed, we'll do an upper endoscopy because that can be done quickly with no preparation before we start worrying about the colon. Now how do we treat lower GI bleeding? If we do identify it in the colon, so we have a lot of options. So hemoclips can both be used prophylactically or preventatively, but they can also be used therapeutically. So in this picture, basically we have a post-polypectomy bleed where someone's removed a polyp and unfortunately they started having bleeding afterwards. You can put a little metal clip on the polyp to basically on the bleeding area to stop it from bleeding. And then we talked about whether these clips would prevent the use of an MRI in the future. We do have some MRI compatible clips, but these clips also do tend to fall off on their own within two or three weeks. So it's usually not an issue. Now if you have a patient who comes in with bleeding diverticulosis, which as I said can be very dramatic in terms of the amount of bleeding. If you're lucky enough to be able to actually see which diverticulum is bleeding, you can treat that with clipping in addition to other modalities. Other things can include epinephrine injection, which we talked about with respect to ulcers earlier. You can use that to slow down bleeding. You can put little rubber bands like the similar ones that we use for esophageal varices, we can put them on hemorrhoids. You can use certain therapies such as APC, which we also talked about with regard to angioextasias in the upper GI tract, and also radiation proctitis as well too. Now diverticulosis, these are these little outpouchings like we were talking about. They are more common with age, but they're usually asymptomatic. So usually diverticulosis is diagnosed during a screening colonoscopy and they say, by the way, you happen to have this condition. They can be located everywhere in the colon. They're more common in the general population on the left side of the colon, but you can see them isolated to the right side, particularly in certain ethnic groups, particularly folks of Asian descent. And as I said, often found diagnostically. We don't do as many barium enemas anymore, but this is a nice photo that kind of shows basically the contrast that's filling up all of these little pouches here. So complications of diverticulosis, you can get something called diverticulitis, and the itis means inflammation. So basically one of the pockets becomes infected. That can cause a lot of abdominal pain. Traditionally, it'll be kind of left lower quadrant abdominal pain. People might have fevers. They might feel a bit constipated. That's usually treated with antibiotics and also diverticular bleeding. So the diverticulitis, as you can see or hear, basically what happens is that one of the little pockets becomes inflamed. Maybe a little piece of poop gets stuck in it or something like that. Over the course of someone's lifetime, 4% to 15% of the patients with diverticulosis will have this during their lifetime, and the symptoms that I said were left-sided abdominal pain, fever. Sometimes your white counts can be increased as well, too. This is usually diagnosed by CT scan, and the circle here is basically showing that there's an area that's thickened from inflammation where the colon here has actually started to burst out as well, too. So treatment for uncomplicated diverticulitis is usually just with antibiotics. And let me say uncomplicated, meaning there's just an infection there. It hasn't perforated through the lining of the colon. These days, actually, there's been a move towards considering that some patients with mild diverticulitis don't even need antibiotics at all. If you can just restrict your diet a little bit, maybe take roughage out of your diet, eat kind of closer to a liquid diet for a few days, a lot of times it'll resolve itself. Now, complicated diverticulitis is when it's been going on for a long time. It's more severe. The colon may have burst or perforated. They may develop abscesses, fistulas, which are connections between different areas of the bowel, bowel obstructions, in which case that needs to be treated with intervention, including interventional radiology to drain abscesses as well as surgery. Diverticular bleeding is when an artery starts to erode into the base of the diverticulum, presents with profuse painless rectal bleeding. However, this bleeding is usually mild in the sense that even though it's very dramatic and terrifying to the patient, usually the patient is able to compensate for the amount of blood that they're losing. Now, treatment of diverticular bleeding, historically, unfortunately, a lot of patients have had to go to surgery to cut out that area of the colon, but these days, sometimes we can treat it with angiography, which is basically doing an interventional radiology study and kind of clotting off whatever blood vessel is bleeding, and also colonoscopy as well, too. Now hemorrhoids, those are swollen veins in the anal canal, and you can have internal hemorrhoids and external hemorrhoids. These can be caused by increased age, but actually just anything that increases pressure around your rectum. So pregnancy is very common. A very common cause is you have extra pressure down there, and then during delivery, if you have a vaginal delivery, the amount of force that you're putting on your pelvis can cause the development of hemorrhoids. Pelvic tumors, for the same reason, increased pressure. Also, fortunately, this is the vast majority of people in this country, but prolonged sitting in a sedentary lifestyle, straining, chronic constipation can do that as well, too. So we can often diagnose hemorrhoids by rectal examination. We can do something called an anoscopy, which we just do in clinic. It's a little tube that goes into the rectum and allows us to see inside and also treat them as well, too. And then also colonoscopy, we often see them. Now, treatment, we try conservative therapy first. So avoiding constipation and straining, and we also use topical steroids and suppositories, things like Preparation H sits baths, which are basically just running a lukewarm bath and kind of sitting in there to help reduce inflammation. There are some procedures we can do at the bedside in clinic, things such as rubber band ligations, sclerotherapy, and then there's surgical therapies, too. So any questions for me right now? That was kind of a whirlwind.

colon cancer

lower GI bleeding

colonoscopy

diverticulosis

hemorrhoids