So, it's my pleasure to introduce my co-chair for session one on gastroesophageal reflux disease, and that's Professor Amit Mahadev from Mumbai in India. It almost appears that both of us are sitting right next to each other, which we do hope we were, and hopefully at some point we will. But Amit's, you know, the chairman at the Baldota Institute of Digestive Sciences, so welcome Amit. The way all the sections have been set up is that there will be two lectures, followed by a case presentation, followed by a panel discussion. And so that's the key part, is the case presentation and the panel discussion, which will sort of blend into each other. And that's where we will be asking our experts all the tough questions. It's also your opportunity to do that. So as Vani mentioned, please go ahead and ask your questions in the Q&A portion at the bottom of the screen. So with that, our first speaker is Dr. Ken Chang, or sorry, Felice, and she will be starting off with the diagnostic toolbox for gastroesophageal reflux disease. Welcome Felice, who is the director of endoscopy at Cornell Medical School in New York. So over to you, Felice. I'd like to thank the course organizers for allowing me to talk on the diagnostic toolbox for GERD, when to use what. This is my disclosure slide. What is GERD? Objectively, it's defined by the presence of characteristic mucosal injury seen in endoscopy and an abnormal esophageal acid exposure, which demonstrated on a reflux monitoring study. Well, GERD is not a one-size-fits-all disease. Symptom generation is multifactorial, and reasons for symptoms may vary from case to case. An algorithmic approach to GERD can only be a guide. In essence, there is no gold standard for the diagnosis of GERD, and this is the reason why. The etiology behind GERD is multifactorial. You can see on this slide, it could be related to low esophageal sphincter, it could be related to defense mechanisms in the esophagus. There are many things potentially at play, and sometimes the diagnosis of GERD is not easy to make. So what's in our GERD testing toolbox? Well, you could see on the top shelf, there are things like the PPI test, upper endoscopy, and reflux monitoring. On the other shelves in our toolbox include things like the esophagram and biopsies, high resolution manometry, and mucosal impedance. We'll go through these things today. But to start, perhaps the most underutilized technology is that of listening to our patient. They will tell us the diagnosis. And most often, the diagnosis is related to the symptoms of heartburn and regurgitation. These are the most sensitive and specific symptoms for GERD. When should one perform a PPI trial? Most consensus statements and guidelines advocate a trial of therapy with PPI once daily as a diagnostic test in patients with typical symptoms, such as heartburn and regurgitation. This is a low-cost and low-risk method. But although it is practical and efficient, the sensitivity and specificity are not perfect. Sensitivity may be 78%, and specificity only 54% in the diagnosis of GERD. So when should one perform an endoscopy? There are three main times where it's essential to do one. The first is when someone has GERD symptoms and alarm symptoms, such as dysphagia, weight loss, bleeding, or anemia. If you choose to do a PPI trial and it is inadequate after eight weeks, or the patient has a recurrence of symptoms after the PPI is discontinued, that would be a time as well to perform an upper endoscopy. And if the patient has chest pain without heartburn and a normal cardiac workup, what should one evaluate at the upper endoscopy? Probably the most important thing is looking at the LA grade classification, which grades the degree of erosions seen in the esophagus. You should note the top of the squamous columnar junction, as well as the top of gastric folds. Identify whether or not there's a hiatal hernia. Grade the size of the hill valve. And of course, as seen here in this picture, look to see if there's barrets, and measure the size of the tongues. Identify whether or not there is a stricture, which is also associated with GERD. And equally important, in patients with dysphagia, one should exclude other diagnoses, such as eosinophilic esophagitis, achalasia, or cancer. Caveats about the upper endoscopy and the diagnosis in GERD include the following. LA grade A erosive esophagitis is not sufficient for a diagnosis of GERD. LA grade B is only sufficient if it is associated with typical symptoms, and the patient also has a response to PPI. LA grade C and D erosive esophagitis, however, is diagnostic of GERD. You can see below on this slide the LA grade classifications and their endoscopic descriptions. So at upper endoscopy, what's conclusive evidence of GERD? Grade C or D esophagitis. The presence of barrets esophagus, especially if it's greater than 3 centimeters. And also identification of a preptic stricture, assuming you exclude other causes for a stricture. For instance, this is not a peptic stricture. This is a Schottky's ring, and often it can be misconstrued as a peptic stricture. Is biopsy helpful in the diagnosis of GERD? We often all take out our biopsy forceps and biopsy the lower esophageal sphincter. Well, you can see here the three different histologic manifestations related to microscopic colitis. And they include papillary elongation, basal cell hyperplasia, and dilated intercellular spaces. Now, although on erosive esophagitis, these three findings can actually be identified very frequently and in normal controls, they're not. But where this really becomes an issue is in our patients, as the ones such as NERD patients and those with reflux hypersensitivity. So routine histopathology, even in expert hands, is neither sensitive or specific for a diagnosis of GERD. What about the barium esophagram? When should you perform it? Well, only 50% of patients with abnormal reflux on esophagram are actually found to have abnormal pH monitoring. So barium esophagus is not recommended solely as a diagnostic test for GERD. Just don't do it if you want to be able to tell your patient whether or not they have GERD. But when is an esophagram helpful in the evaluation of a patient with GERD symptoms? Well, these are three times where it really probably should be done. It is very sensitive for rings or subtle strictures or to assess luminal diameter. So in patients with dysphagia, this may play a really important role. Equally true, it is likely the best test for identification of a hiatal hernia as well as a parasophageal hernia, which could be very challenging for endoscopic times to be able to diagnose endoscopically. And also, a well-performed normal study will almost always eliminate a diagnosis of achalasia. Moving on to reflux monitoring. What metrics make the diagnosis? Well, here you can see six different metrics, acid exposure time, the number of reflux events, reflux symptom correlation, the presence of weakly acidic or non-acidic reflux, estimating bolus clearance, and also identification of the extent of proximal reflux. Of all of these, however, acid exposure time is clearly the most important metric in making the diagnosis for reflux. What amount of acid exposure time is diagnostic, however? Here you can see historically many of the different studies that were done to try to understand the upper limit and the lower limit of normal at reflux monitoring. In the end, an acid exposure time of greater than 6% is deemed abnormal. And if it's less than 4%, that is considered normal or physiologic. What about how many reflux events are identified at reflux monitoring? How many are necessary to be considered abnormal? Here you can see a study that was looking at healthy volunteers, those with NERD, and those with erosive esophagitis to be able to answer that question. The one thing to keep in mind, however, is that reflux episodes also are not solely diagnostic for GERD. And they should only be used as an adjunctive measure when the AET is inconclusive. But what number is considered abnormal? Well, if someone has greater than 80 reflux episodes in 24 hours, that is considered abnormal. And less than 40 is physiologic. Another important thing is that prolongation of reflux monitoring truly can add potential value. And here we see when we do our wireless monitoring and extend the test up to 96 hours, you can actually take a patient who potentially we would not identify the presence of abnormal acid exposure. You can bring it out when you increase the amount of time that you do studies. And when you have a patient that has concordant days, two days, three days, or certainly four days where there is increased acid exposure time, that is most definitely adding value to the diagnosis of GERD. What about the role of reflux symptom correlation? Well, there are two indices that we talk about in this. The first is the symptom index. And the other is the symptom association probability. Those with a positive symptom association absolutely do better with medical management and surgery. But this also has a limited value as a standalone test in the diagnosis of GERD. The patients in which we can have the most confidence, however, are those that have a positive acid exposure time as well as a symptom association probability. When should we add impedance pH monitoring to our testing? Well, there are two instances where it probably plays a big role. Impedance monitoring is much more sensitive in the detection of rumination and belching disorders. And also, it is most valuable when it's done on PPI-BID. As in this instance, you can test for weakly acidic or non-acidic reflux and assess the symptom relationship. Putting this all together, when should one perform a pH impedance study versus a wireless pH study? Well, a wireless pH study should almost always be done off of a PPI. This is really a wonderful test in patients that have infrequent symptoms because you can extend the amount of testing up to 96 hours. It's also great for patients that are just not able to tolerate the catheter and those that have a negative 24-hour reflux monitoring study, but you really have a high clinical suspicion that they have reflux. Wireless pH is probably the way to go. Now, for pH impedance, this really plays a big role for patients with refractory symptoms on PPI. And also, as I mentioned before, those that you have a suspicion for rumination or a belcher. And this also plays a role for patients with respiratory symptoms. Another new metric is the evaluation of nocturnal baseline impedance. This is when impedance is measured as a value at rest because it's done nocturnally. There's less interruptions in the study, less swallowing at that time. And here, at this study, the lower the baseline impedance, the higher the likelihood of pathological reflux. This type of study can actually be extracted from the software that you currently have. It's not often used by everyone, but this certainly should be thought about potentially as another additional tool in the diagnosis of GERD. Extrapolating further on the impedance piece was the development of this balloon mucosal impedance device. This device can be placed endoscopically at the time of upper endoscopy. And you can see the balloon in the figure that's inflated. And it has impedance catheters throughout the balloon. You can actually measure the impedance along the entire esophagus. And here, you can see the lower the impedance is actually in the middle will project a red out. And that is actually diagnostic for eosinophil esophagitis. Equally important is that if a patient does not have reflux on mucosal impedance, you will get very high readings. And the entire thing will look blue. I've also depicted the way normal as well as reflux will look on mucosal impedance. So it's another device. It's still in study. But one should keep an eye out on this technology as well. What is the role, however, of regular high-resolution manometry in the diagnosis of GERD? Well, this provides an evaluation of peristalsis and esophageal clearance. And as I mentioned before, it can play a big role in two patients, those with behavioral disorders such as rumination as well as supragastric belching. So putting it all together, there are three major things potentially that we would be doing. Obviously, our endoscopy as well as PA. And perhaps in some places, high-resolution manometry. So the conclusive evidence of pathological reflux, if you identify LA-grade C or D esophagitis, a long segment of Barrett's esophagus or peptic stricture, and in those patients, an acid exposure time greater than 6%, this is diagnostic of GERD. However, evidence against pathological reflux would really mainly be on pH testing if you have an acid exposure time of less than 4 and perhaps also less than 40 reflux events. All your labs are back. They show a serious overuse of unnecessary and inappropriate tests and procedures. I hope today I showed you the necessary and appropriate tests to diagnose GERD. Thank you so much for your time.

gastroesophageal reflux disease

diagnostic toolbox

symptom generation

PPI test

upper endoscopy