We have more case studies being tackled by ATP and physician teams. Starting us off will be Dr. Sumit Tiwani, joined by Janelle DeFilippis. Janelle is a board-certified acute care nurse practitioner, specializing in the care of hospital patients with GI problems. She received her BSN degree from St. Anthony College of Nursing in 2007. She earned her MSN and acute care certification from the University of Illinois in Chicago in 2012. As I said, Janelle is a hospitalist, and she's really developed quite an expertise in the area of MRCP and CT imaging of the abdomen and pelvis. She's become quite the interpreter of images. So Janelle, Sumit, take it away. All right. Well, thank you, Joe, and thank you for having me partake in this conference. So Dr. Tiwani and I will be going over radiology studies case number two on common bile duct stones. We have no disclosures. So our patient is a 32-year-old woman who presented to the emergency department with postprandial epigastric pain, nausea, and vomiting for one week. The patient denied any fevers, chills, diarrhea, constipation, sick contacts, or recent traveling. She also denied any alcohol, tobacco, or illicit drug use. On physical exam, she had tenderness in her epigastric and right upper quadrant with a negative Murphy sign. And her labs were notable for a total bilirubin of 2.6, AST of 338, ALT of 309, alkaline phosphatase of 149. Her lipase was normal, and her white blood cell count and hemoglobin were normal. So what imaging study should be performed first in our case? OK. All right. So the majority of you got that correct. We would start with a ultrasound. So ultrasound is helpful in identifying cholelithiasis, cholecystitis, and any biliary ductal diltation. There can be anatomic variations in position, shape, and size of the gallbladder. But in general, the gallbladder typically measures around 7 to 9 centimeters in length, has a round or pear shape, and the walls are less than 3 millimeters. On ultrasound, gallstones appear hyperechoic with posterior acoustic shadowing. And the normal common bile duct is typically 6 millimeters or less with the gallbladder in place. However, there can be mild dilation related to advancing age. So you can estimate an increase of approximately 1 millimeter for every decade over the age of 50. And a dilated common bowel duct is suggestive of choledocholithiasis. So overall, the abdominal ultrasound has relatively poor sensitivity for detecting common bowel duct stones directly. It's especially poor for the distal common bowel duct, because that's often obscured by bowel gas. The sensitivity does increase for stones when there's CBD dilation. So as you can see here, for a diameter over 10 millimeters, that has about a 50% risk of a common bowel duct stone. And a normal common bowel duct on ultrasound has a very high negative predictive value for choledocholithiasis. So this is an ultrasound image of a gallbladder. You can see it has a pear shape and contains two stones that are hyperechoic with posterior acoustic shadowing. When viewing a gallbladder on ultrasound, you're really assessing for any gallstones, gallbladder wall thickening, or pericolcystic fluid. And gallstones are typically dependent, meaning they move with gravity as opposed to gallbladder polyps or masses. This is another ultrasound image of a dilated common bowel duct containing a single stone. You can see there's a hyperechoic stone with a posterior acoustic shadowing. So next for CT, the sensitivity for gallstones on CT can be limited for a variety of reasons, including the composition and size of the gallstones. Structure calcified stones are seen more easily than, for example, if the stone is smaller or composed of cholesterol. Stones in the common bowel duct on CT imaging can have a rim or target sign, you can see in the picture on the right, where the stone has a surrounding darker rim of fluid. And although the sensitivity for detecting gallstones on CT is not very good, it is improved just like it is on the ultrasound when the common bowel duct is dilated. Lastly, the CT can be beneficial in identifying other pathologies such as mass lesions or pancreatitis. So MRCP has a greater sensitivity for detecting common bowel duct stones when compared to CT and ultrasound. It can also evaluate for biliary strictures. It has the added benefit of not utilizing any ionized radiation or contrast. And in general, there is a lower sensitivity for smaller stones, detecting stones in a non-dilated bowel duct or for assessing any peri-ampullary pathology. So this is an MRCP coronal image, and as you can see, the common bowel duct is coming down into the duodenum. And in the distal common bowel duct, you can see multiple filling defects consistent with choledocal athiasis. And here is another MRCP image. You can see similar filling defects in the distal duct going up above that. So you've got the left and the right hepatic duct coming down into the common hepatic duct and down into the common bowel duct, which goes into the duodenum. And I'm going to turn it over to Dr. Tewani. Thanks, Janelle. So as Janelle already mentioned, we've covered the ultrasound, CT scan, and MRCP. And this is a nice table that kind of allows you to compare the sensitivities and specificities of each of the modalities that we've discussed so far. As already mentioned, the sensitivity of ultrasound is very low, but has a good specificity. And sensitivity does increase in the presence of CBD dilation. CT scan has somewhat better sensitivity, specifically when we're looking for calcified stones. But its major advantage is that it's going to allow us to look for other potential diagnoses such as pancreatitis or neoplasm. The downside of CT scan is that it does involve radiation and contrast, particularly when you're looking for those alternative diagnoses. MRCP is one of the preferred or best modalities with high sensitivity and high specificity. Disadvantages to this are that because of the nature of MRI, patients who have claustrophobia issues or overweight, this may not be an optimal choice for them. And then finally, on the bottom there, we have IOC. IOC, I think Dr. Martin had alluded to in his talk as well, is an intraoperative cholangiogram performed at the time of cholecystectomy. So when the surgeons are performing the cholecystectomy, many times they can access the cystic duct and inject contrast there and use fluoroscopy in the operating room. And this comparatively has, again, very high sensitivity and specificity for common bile duct stones. It does add about 10 to 15 minutes of time to the procedure itself, but is a nice alternative depending on what your local expertise is. Then I'm going to talk a little bit about the endoscopic option. So endoscopic ultrasound should also be considered as an option, particularly for those patients that we consider to be at intermediate risk of choledocal diasis, and especially in those patients who cannot have an MRI done, for instance, because of claustrophobia or weight limitations or also a pacemaker or ICD. Endoscopic ultrasound has very high sensitivity and specificity, very comparable to MRCP. It is highly sensitive for those small stones that are less than 5 millimeters, where MRCP may be more limited. It does carry, because it is invasive and does involve sedation or anesthesia, it does have a very low, but not zero, complication rate. The complication rates for EUS are very similar to those for upper endoscopic colonoscopy when we're not talking about biopsies, biopsies will increase those risks. But as I said, high sensitivity and specificity for common bile duct stones. And when you're comparing endoscopic ultrasound to MRCP, you can see here higher sensitivity and diagnostic odds ratio when you're directly comparing the two. This study actually showed a cost savings for EUS by avoiding the expense and the adverse events of ERCP in the sense that instead of, sorry, this was in comparison to going directly to ERCP, the ERCP, as was previously said, is no longer really considered an option for diagnostic purposes. And so EUS does offer the opportunity to avoid that expense and the risk associated with ERCP. And EUS is cost effective over MRCP, although in this study, they didn't really include all the costs that may be kind of more standard at this point, including like the cost of anesthesia, the risk of adverse events. And keep in mind too, that EUS does have operator dependence as does sometimes MR in terms of our radiologists. But there's important reasons to consider EUS as a reasonable alternative to MRCP. This was covered also by Dr. Martin in his excellent talk. But when we talk about the risk of colodocal athiasis, we break it down based off of the presence or absence of certain risk factors. The highest risk would be the actual identification of a common bile butt stone on ultrasound or other imaging, the presence of acute cholangitis or the high suspicion for acute cholangitis, or the combination of an elevated bilirubin greater than four and the presence of a dilated bile butt on imaging. And by dilated, they use the definitions of six millimeters in a patient who has their gallbladder in place or eight millimeters in those who've had a cholecystectomy previously. So any one of those three factors would be considered high risk for colodocal athiasis. Intermediate risk would be those that fall in the second row there. So abnormal liver enzymes, age greater than 55, or the presence of a dilated common bile butt on imaging. And then low risk would be those that have none of the above risk factors. This is from our ASGE guidelines. And those were originally, I think, from 2010 and there was an update in 2019. The major update in this most recent update from ASGE showed improved specificity when they combined the threshold for total bilirubin greater than four with the presence of common bile butt dilation. So when you combine those two as the necessary for meeting the high risk criterion, that showed improved specificity for CBD stones. Again, six millimeter threshold versus eight millimeter threshold. And then proceeding with management, this is where ERCP really plays its major role. I won't go into details about the procedure itself, but ERCP is indicated for management of common bile butt stones. Again, for patients at high risk who meet any of those high risk criteria, you may proceed directly to ERCP given your high suspicion for choledoplathiasis. But those that fall in the intermediate risk category where they don't quite meet all the criteria, you would consider one of the diagnostic modalities previously discussed and your best options there are MRCP, endoscopic ultrasound, or cholecystectomy with intraoperative cholangiogram. Again, the choice of that will depend on what resources you have, what your local expertise is, do you have easy access to radiology versus endoscopic ultrasound or general surgery, and what's the general surgeon's confidence in doing intraoperative cholangiograms as well. And then those with low risk who don't have any of the above risk factors for choledoplathiasis, they may proceed directly to cholecystectomy without requiring preoperative testing. A little bit more about ERCP. So ERCP is highly sensitive and specific as in it is the gold standard for detection and management of choledoplathiasis, but it is associated with higher complication risks as already discussed, including a 6 to 15% rate of adverse events and 1 to 2% risk of severe adverse events, including prolonged hospitalization and life-threatening pancreatitis or other complications. You can see the risks of pancreatitis, infection, hemorrhage, and perforation listed below. And then one option is also what we call EUS-directed ERCP or EUS-possible ERCP. This is kind of combining both EUS and ERCP in one setting where we start with an endoscopic ultrasound for those patients who fall in that intermediate risk category to be immediately followed by a therapeutic ERCP when that is indicated. So the EUS performs the diagnostic ability to identify the CBD stone and if CBD stone is present, proceeding with the ERCP for management. If CBD stone is not identified on EUS, then the ERCP can be canceled or can be eliminated. The benefit is that both of these are performed in the same setting. One round of anesthesia could make for a little bit of a lengthy procedure, but when we're really doing this for a common bile duct stone, you don't typically have to do a lengthy examination. It's really just to identify CBD stones and maybe assess the gallbladder follow-up diases. So those patients that are in that intermediate to high risk category, these studies identified when you looked at the patients that ultimately went to ERCP, 27 to 40% actually had CBD stones. And so it actually eliminated the need for that ERCP in a majority of those patients in that intermediate risk category. And so the negative predictive value of EUS is as high as 96 to 100%. Again, very, very similar, very, very high numbers compared to MRCP. And cost effective to start with an EUS when the likelihood of CBD stones is less than 60%, specifically by attempting to avoid the costs associated with resources and adverse risk related to ERCP. And our final slide, this is the table from the ASG guideline in 2019 that basically summarizes what we've talked about in this talk. This is our one and only major pearl. Thanks.

postprandial epigastric pain

common bile duct stones

imaging modalities

MRCP sensitivity

ERCP management