We're now ready to take on our Q&A. I will ask this one of Vivek and Sarah. How much time can it take for a solid pseudopapillary tumor to develop to the point of patient experiencing symptoms and signs? Yeah, so that's an interesting question. I saw that on the chat. You know, typically these lesions will not create too much symptoms for a long time, actually. There are some tumors in medicine that are not purely floridly malignant, and they are not obviously benign. They're kind of in this middle zone. And S-pens belong in that zone. I think in my experience, from what I know, it's the mass effect that can create issues. And of course, if they create pancreatitis type or obstructive symptoms, then those symptoms may present early. So if they're near a bile duct, you can choke the bile duct and it might present a little sooner than if it was in the tail. And certainly if there is an obstructive pancreatic symptomatology going on, then a patient might present with those symptoms. But typically, a long time, and even then, very subtle. Okay, another question. I think it's a good one. One of our colleagues in the audience said that they noticed that some gastroenterologists kind of make their decision, if I'm getting the question right, to stent or not to stent, perhaps based on total bilirubin alone. What are the thoughts on that? Right. So I'm not quite clear what the question is, and I'll ask John to comment on it as well. But stenting in ERCP is a nuanced intervention and has gone through a lot of evolution. I will restrict my comments for plastic biliary stenting. I think that's where the question is right now. And for the vast majority of patients where you have cleared the duct of stones, typically, and the patient does not have cholangitis, and there's not a biliary structure, the job is done, the guidelines do not recommend placement of a stent, because that would invoke a second procedure and more work and more morbidity and cost. But the latest guidelines have suggested that if the patient is undergoing ERCP for cholangitis, obviously, the bilirubin typically is elevated in these patients. Even if you have cleared the duct, they are recommending placement of a stent for some ongoing biliary drainage for biliary sepsis. Now, in terms of bilirubin up or not, I think it's more important what the pathology you're stenting for rather than the total amount of bilirubin. And so if there is a structure and the contrast is not draining, that patient is going to get into trouble if you don't stent that patient. Now, so typically, those patients who have pathologic structures will have an elevated bilirubin. So it's uncommon for somebody to have a florid structure and then have a normal bilirubin, especially if the disease is going on for a length of time. So in general, we will stent when the bilirubin is elevated, and there is existing pathology that the stent will palliate. John, welcome your comments on that. Thank you, Vivek. You pretty much covered it. I think the only thing I would add is, you know, basically, like you said, a stent is used to overcome obstructions. It's a drain pipe. And so if you need a drain pipe, you put one in. I mean, if the bili is up because the liver cells are sick, well, that's not a drainage problem. And so that jaundiced patient with hepatocellular jaundice wouldn't benefit from a stent. And sometimes the bilirubin may be normal, but you've just injected the duct and it's not draining because the structure is too tight to drain durably. You may place a stent so that the patient does drain because they have an impending obstruction. It may not be jaundiced with an elevated bilirubin today, but you're pretty sure they're going to be in two weeks. The other situation where we commonly introduce biliary stents is where you want to increase the durability of effect of the dilation that you're performing. There is old literature that demonstrates that if you dilate a stricture, whether the bilirubin is elevated or not, let's say in this case that the patient is jaundiced, and they're jaundiced because they have a bile duct stricture. You can either dilate that bile duct stricture and not stent the patient, or you might dilate that bile duct stricture and place a stent. Well, there is evidence that shows that if you dilate and place a stent, you'll double the durable response to that dilation by putting that stent in for some period of time. So sometimes we place that stent to increase or better the effect of the balloon or passage dilation that we perform for a stricture. John, just last comment. I think most of the audience may remember a video I showed this morning, maybe not, of the stents can create problems. And stents can perforate, they can migrate, they can create bleeding. So it's a problematic issue if the endoscopist has placed a stent, and there is not a good justification for it. So it has to be kept in mind, and that's why these conversations are very important. It was a great question. All right, we have another question. If a CT is being done for choledocal athiasis, should IV contrast be used? And I can throw that out to John, Vivek, Sarah, whoever wants to jump in. Yeah. So the answer is yes. Unless there's a contraindication to it, you're going to introduce IV contrast, but not oral contrast. I mean, the GI tract is already blocked. So the last thing you want to do is you have a full glass of water, and you're going to pour more water into the glass. You don't want to do that. Worse yet, they're going to drink that, and then they're going to vomit it, and that contrast is going to enter the airway, and that's not a great thing to aspirate, oral contrast. With CT these days, they can tune it so that the fluid that's in the bowel actually ends up being the oral contrast equivalent. So you don't need to give oral contrast. IV contrast is given for a good reason. You know, if you think about it, our bodies are mostly water, right? And because of that, a CT, which is just a fancy X-ray, is not going to do a great job of differentiating the different waterlogged tissues of the body. I mean, obviously, bones are going to look different, but all that soft tissue that's in the belly, it all looks pretty much the same. But if you introduce contrast through the vessels, intravenous contrast, different tissues have different amounts, if you will, or different densities of blood vessels running through them. They have differential perfusion. And so contrast introduced intravenously differentially opacifies the different organs because of their different circulation aspects of the different tissues, thereby generating the ability for that X-ray or CT in this instance to show you the different organs at different gray scales of opacity. And so you want to be able to tell the bowel from the liver, from the pancreas, from the mesentery and so forth. And the way to do that is by taking advantage of the fact that you know that the different organs have different vessel densities running through them. And when you run the contrast through there, that they're going to appear distinct from each other. So the IV contrast, you bet. The oral contrast, don't, they're already vomiting. Don't make a bad situation worse. And to just add, I think, you know, CT is not my go-to imaging for CBD stones. You know, trans-abdominal ultrasound would be a cheap, easy way, non-invasive way. And then typically most centers are now doing MRCPs if that's needed or EUS. A CT happens to pick up stones, but in general, we don't order CT scans from the clinic to look at the biodegradable stones. My apologies. I thought we were talking about bowel obstructions. Oh, I may be wrong. No, I think you covered both of them well. So that's great. I think it was about the biliary tree, but I'm not sure, but we covered them both well. So that's a two for one. Excellent. Vivek, I have one for you. Is there a preferred, or Sarah, either one of you can jump in. Is there a preferred imaging modality when chronic pancreatitis is suspected? Again, Sarah, Vivek, either one. Yeah, I'll keep it short because I was involved with it in my EUS fellowship. So short answer from my side, and Sarah can comment because she has a vast experience in this from clinic. It depends on the stage of pancreatitis for the only test that picks up, the only imaging test that picks up early mild chronic pancreatitis is EUS. A plain film will pick up calcifications in the pancreas and a CT scan, of course, will pick up advanced disease like calcification, but early mild chronic pancreatitis, if there's an imaging test, that's EUS. Sarah? Yeah, I agree. I think a lot of times we end up starting with a CAT scan because we're investigating symptoms unless you really have a high index of suspicion for chronic pancreatitis. But I think a lot of times in our kind of diagnostic workup, it is a little bit lower on the differential diagnosis, or you want to rule out other acute things first. So you may already have a CAT scan, and if it doesn't show any evidence, absolutely, we definitely would go to the endoscopic ultrasound. Okay. This next one, we'll go back to John. We have a couple more left, and I think we have time to finish them up. Our colleague says, I've had patients that show cholelithiasis on imaging, but no total bilial elevation. Why? Thoughts? Okay. So first we need to determine whether you're talking about cholelithiasis or choledocholithiasis. This is choledocholithiasis. Sorry to interrupt. Okay. So choledocholithiasis is the scenario of having a bile duct stone, and cholelithiasis is having a gallbladder stone. If the stone's in the gallbladder, it's probably not obstructing the bile duct in most cases, and so it's not going to cause a bili elevation. In choledocholithiasis, where there's a stone in the bile duct, it's a simple mechanical answer to your question. The stone may be just floating around in the bile duct and not causing obstruction, and certainly not causing obstruction long enough for the bilirubin to be elevated. So if and when a stone obstructs transiently for, say, a short time, the first thing that'll rise in the bloodstream is the aminotransferases, AST and ALT, because those are stored in the hepatocyte and ready to be released any time the liver cell becomes unhappy. They get released into the bloodstream, and you can measure them right away. Those are the first things to go up. And then if the bile duct is obstructed longer than that, the cholangiocyte, the cells that line the biliary tree, that condition of obstruction may induce the bile duct cells to start producing alkaline phosphatase, and when they do so, that can get into the bloodstream, and then that'll be the next thing to go up. The last thing to go up is the bilirubin. The bile duct actually has to be obstructed constantly for long enough for the bilirubin to rise. So it's the last thing to go up, not the first thing to go up. And so transient biliary obstruction usually doesn't cause the bilirubin to go up, but it might cause the AST and ALT to go up, and if longer still, the alkphos might go up. And finally, the last thing to go up will be the bili, and by the time the bilirubin's going up, imaging will usually demonstrate bile duct dilatation. Okay. Thank you, John. Very quickly, I'll just add, since we do have some time, you know, I have seen a completely packed bile duct with normal LFTs. This happened within the last year, actually. I just cannot explain it. It's a fantastic question. I think the body reacts in different ways, and that's why it's mystical. But I just never, I never understood it. And sometimes it is a, the smallest concretion, it is a three, four millimeter stone, patient comes in, severe gallstone pancreatitis, bilirubin up the gazoo, and you go in there, and there's hardly this concretion, and you're left imagining, you know, how can such a small pathology create so much fuss? It is, there's a lot of mechanisms we don't understand fully. Let me put it that way. I've got one for Samit, and Samit, if you want to look in the QA and read along, that's fine. If a patient presents with a plastic biliary stent without being a good historian, besides a plan to remove the stent, what would you typically do to manage this patient if there's no medical documentation available, and the patient is unsure why and when the stent was placed? And I know we've all come across this, even a non-biliary guy like me. So really, the patient comes along, not a great historian, plastic stent is in place, don't know anything else. What would you be doing and thinking, Samit? Well, I'd be thinking along the lines of why might a CT stent have been placed in the first place, so whether there was a stricture or concern about cholangitis or inadequate duct clearance in somebody who had multiple bile butt stones. So if we're thinking along the lines of a stricture, I think some sort of imaging cross-sectionally ahead of time would be nice, either a CT scan, or preferably a CT scan, basically, to make sure there's not any obvious reason that the stent might have been in. So CBD stone, or more importantly, a pancreatic mass. If that's addressed and there's no obvious findings on the CT scan, then at the time of the ERCP to remove the stone, I think you really need to do a good quality cholangiogram to see if there are any subtle abnormalities, if there are any retained stones, if there are any strictures, maybe evidence of Maritzi syndrome or something like that, where it's more subtle, you wouldn't be able to identify that once the very stent's in place. So if they're not cholangitic, I'd prefer a CT scan up front to make sure there's not any obvious reason, and then follow that up with a good cholangiogram during the ERCP to remove the stent. And if that looks normal, maybe there was some concern on the previous ERCP that maybe there was inadequate clearance of the dutch for stones, and once you've ensured that there's adequate clearance, I would opt not to replace the stent. That's how I would generally approach it. Very good. Thank you, Sumit. Another one for you, Sumit. I was leaving you alone, but now I'm going to pick on you. If a patient has pancreatic insufficiency and the pancreas appears normal on CT scan, do you plan to repeat imaging looking for underlying pathology in a future date, or do you do another imaging study up front to try to work through this? Yeah, so I generally like MRI or endoscopic ultrasound when you're looking for more subtle indications for, like as Dr. Cole had mentioned, subtle findings related to chronic pancreatitis or early changes of chronic pancreatitis. Now theoretically, if they've got pancreatic insufficiency, they should have more advanced findings on imaging, and you should be able to generally see that on cross-sectional imaging like CT scan. You may, instead of that, start to explore either direct or indirect testing for pancreatic function, so thinking about a fecal elastase level or more invasive testing as we do to test bicarbonate secretion and things like that from the pancreas itself. Those are more complicated, generally done in academic centers, so not something, for instance, that I would have easy access to, but I think an endoscopic ultrasound and a fecal elastase would be two things that I would consider if I'm really concerned about the possibility of pancreatic insufficiency. You also want to remember that these tests are not necessarily specific, so if you have a positive fecal elastase level, it doesn't necessarily 100% clinch the diagnosis of pancreatic insufficiency. You have to think about small bowel disorders and other disorders that could also lead to malabsorption issues, so keep that in mind to keep a broad differential at the same time, but that's how I would approach that. Very good. Thank you, Samita. Go ahead, Sarah. Sorry. Sorry, if you don't mind. Thank you for that point. I think that that's really important to remember, especially if you're making the diagnosis of EPI based on the fecal elastase. If the patient had done a stool sample when they had diarrhea, you really want to firm their stools and repeat it to see if you can get a more accurate level. Any secretory diarrhea is going to give you a low fecal elastase or can give you a lower one, and so in order to try to make that as accurate as we can, still not the best test we know, but it may be the best easily available one, then you want to firm their stools first and then repeat it. Thank you, Sarah. I think we have time for one last question, and it's a bit of a clarification. Our colleague writes, maybe I misread the slide, but for pancreatic cystic lesions, is the preferred modality CT pancreas protocol of contrast? I thought MRI pancreas was preferred unless they had a contraindication. So, Sarah, Vivek, actually John or Sumit, anybody want to jump in? MRI is preferred generally. The radiation risk is less, but Sarah, go ahead and let's review the pros and cons of CT versus MRI in general. Yeah, so I think they're comparable in the sense of being able to look at them. I agree. MRI, certainly if there's no contraindications to MRI, if they can sit still, if they're not terribly claustrophobic where they're scratching and clawing to get out of the machine, then MRI is good because of that contrast. CT scan will certainly show it well. And so I think it depends, you know, a lot of times when we find these pancreatic cystic lesions for that initial diagnosis, we're seeing them incidentally. And so you may have a CAT scan for that reason. I would certainly follow them up with MRI pancreas if they don't have any contraindication though. I might also add that it kind of depends on your availability of local expertise as many things do in clinical medicine. So it depends on whether your abdominal imaging team is more versed in high quality MR or if they are tending to more be disciples of CT. If you have really, really proficiently even expert abdominal MRIists in your radiology team, there are more nuances that they can ferret out of properly protocoled MRIs than abdominal CTs like small communications to a cystic collection. If they communicate with the doctor or something of that nature, they can often get more information with cystic lesions out of an MR, but it depends on how well it's protocoled, how enthusiastic the radiologists and the entire radiology team are at practicing by those protocols and innovating, et cetera, et cetera. So you really need to find out from your own radiology team where they feel their expertise is for certain clinical indications like this. All right. I think with that, we'll wrap up the Q&A. And really, wow, what a terrific day. I want to tell you that we had some people sign up today. We actually had 278 of our colleagues on board, which is starting to get to be a little bit significant in breaking our record of attendance, which makes us very happy. We had a very good day. It's a long day, so thank all of you for staying with us. We had started off with some practice management topics. We moved on to endoscopy, covering the basics and advanced endoscopy, and we really had, I think, a really fun session on radiology, and you can see the collaboration that exists between the APP physician teams on this course, but it really reflects what happens in the real world. You have become indispensable to the field of GI, and teamwork really is the key. And so I really can't wait for tomorrow, but have a nice dinner and sleep well, and we'll do this again tomorrow.

gastrointestinal issues

biliary stenting

IV contrast

choledocholithiasis

imaging modalities

teamwork