ERCP and EUS Procedures: Safe Cannulation and PEP Prophylaxis

0:00Welcome to Board Pearls. This is episode one of seven of the ERCP and EUS Procedures chapter, in the Endoscopic Procedures module. In this episode we cover how to get into the duct safely: why ERCP is a therapy and not a test, the cannulation technique that holds post-ERCP pancreatitis in check, and the prophylaxis stack built to push that risk down.

0:23Start with the single fact that organizes everything else about ERCP. It is a therapy, not a test. The day a diagnostic ERCP was a reasonable thing to do has passed. If all you want is to see the anatomy of the biliary and pancreatic ducts, you order an MRCP or you do an EUS. Both image the ducts without putting an instrument into them. ERCP cannot do that. To opacify a duct, the endoscopist has to cannulate it and inject contrast, and both of those acts can set off pancreatitis. Cannulation traumatizes the pancreatic orifice, and contrast under pressure pushes fluid back into the acini, where it raises pressure and activates trypsinogen. So when a non-invasive study can answer the question, choosing ERCP means accepting pancreatitis risk for nothing. That is why the procedure is reserved for cases where you intend to do something. Pull a stone out of the common bile duct. Stent a stricture. Decompress an infected, obstructed duct in cholangitis. Seal a bile leak. Manage an ampullary lesion or pancreatic ductal disease. Every accepted indication is therapeutic, because the diagnostic justification has been taken over by imaging that carries none of the risk.

1:39Once you commit to the procedure, the risk you are managing has a name and a number. Post-ERCP pancreatitis, PEP, complicates roughly four to nine percent of unselected cases, and fifteen to thirty percent of high-risk ones. Everything from here forward is built to push those numbers down. And the first lever is the cannulation technique itself.

2:01There are two ways to find the duct. You can inject contrast and watch where it goes, or you can thread a soft hydrophilic guidewire through the papilla first and confirm you are in the right duct before any contrast moves. Wire-guided cannulation is the one that lowers PEP. The reason is mechanical versus hydraulic. Contrast-first cannulation works by pushing fluid, and when the wire or catheter is not yet seated in the bile duct, that fluid frequently goes into the pancreatic duct instead. Push enough and you opacify the fine acinar branches, a phenomenon called acinarization, and that is a direct pressure injury to the acinar cells. Wire-guided cannulation replaces the fluid push with a thin wire advanced under tactile and visual control, so the duct is identified by guidance rather than by flooding it. Same goal, no hydraulic insult.

2:50Sometimes the wire will not go. Cannulation is difficult, and there is a standard escalation, but the point is not to memorize a list of maneuvers. It is to see that each one solves a specific anatomic problem. The double-wire technique is for a papilla that keeps deflecting your biliary wire into the pancreatic duct. You leave a wire in the pancreatic duct on purpose. That wire straightens and anchors the papilla, so the second wire has a stable, predictable axis to follow into the bile duct. Transpancreatic septotomy is for anatomy where the biliary orifice is hidden behind prominent transverse folds or a stenotic papilla. You cut along the pancreatic septum with cautery to expose the biliary opening. Needle-knife precut is the most aggressive step, a freehand incision over the bile duct when nothing else has worked. It carries higher PEP and perforation risk because you are cutting without an established cannulated tract to guide the blade. That is why it comes last, and why it is safest done over a pancreatic duct stent. The stent both marks the pancreatic orifice and shields it from the thermal injury of a misplaced cut. And when antegrade endoscopic access fails entirely, the modern fallback is the EUS rendezvous. You puncture the bile duct under ultrasound, pass a wire down across the papilla, and then retrieve that wire from the duodenal side with the duodenoscope. That has replaced the old percutaneous transhepatic rendezvous.

4:11Notice that difficult cannulation is itself a risk factor for pancreatitis. More attempts, more wire passes, longer time at the papilla, more inadvertent pancreatic duct entries. So the technique that gets you in cleanly is also the technique that protects the pancreas. The two are the same problem.

4:29Now the prophylaxis stack. Three things have randomized trial support, and the way to hold them is by mechanism, because the mechanisms are different and that is exactly what tells you who needs which.

4:41First, rectal indomethacin, one hundred milligrams, given in all native-papilla ERCPs. Native papilla means the sphincter has not been cut before, which is when the pancreas is most vulnerable. The mechanism is anti-inflammatory. The nonsteroidal blocks phospholipase A2, cyclooxygenase, and lipoxygenase, which are the enzymes that drive the inflammatory cascade once acinar cells are injured during cannulation. You give it rectally because that route absorbs fast and bypasses gastric first-pass metabolism. And you give it before the procedure, so that the drug level is already therapeutic at the moment of cannulation, when the injury happens. The evidence here is worth keeping straight. The pivotal trial established the benefit in high-risk patients, where indomethacin cut post-ERCP pancreatitis roughly in half, and that study was high-risk only. The reason indomethacin is now given to everyone with a native papilla is that later guidelines extended the recommendation on additional average and lower-risk data, so current guidance is universal use. The trial taught the high-risk effect, and the guideline generalized it.

5:50Second, the prophylactic pancreatic duct stent, and this is where a tempting shortcut fails. Once you know indomethacin works, it is natural to wonder whether the drug alone is enough and you can skip the stent in high-risk patients. That was tested directly, asking whether indomethacin alone was non-inferior to indomethacin plus a pancreatic duct stent, and it was not, because there was more pancreatitis in the no-stent arm. So in high-risk patients the stent stays, on top of indomethacin, not instead of it. The mechanism is purely mechanical and separate from the drug. Cannulating the pancreatic duct causes the papilla to swell, and that edema can obstruct pancreatic outflow in the hours after the procedure, building exactly the pressure that triggers pancreatitis. A small-caliber stent holds the orifice open until the swelling resolves, then either passes on its own over a few days or comes out at follow-up imaging.

6:45Third, aggressive periprocedural lactated Ringer. This one protects the pancreas through perfusion rather than inflammation or outflow. Generous fluid maintains pancreatic microcirculation during the inflammatory response, dilutes the inflammatory milieu, and corrects the dehydration that fasting and prep have already produced. The protocol is worth knowing exactly because it gets tested as a dose. Three milliliters per kilogram per hour during the procedure. A twenty milliliter per kilogram bolus immediately after. Then three milliliters per kilogram per hour for the eight hours that follow. Lactated Ringer is chosen over normal saline because the lactate is a bicarbonate precursor, and that buffers the metabolic acidosis that a large saline load would otherwise create.

7:31And then there are the agents that did not survive the evidence. Octreotide, gabexate, and intravenous secretin are not recommended. They sound mechanistically plausible, which is why they were once used, but they do not reduce PEP, and current guidance leaves them out.

7:46So who is the high-risk patient that earns the full stack. Run the same risk logic and the list builds itself. Suspected sphincter of Oddi dysfunction, because that procedure means repeated cannulation and frequent pancreatic duct entry. A prior episode of PEP, which marks a patient whose pancreas has already shown it will react. Female sex. A normal bilirubin, which sounds reassuring but is not. The absence of obstruction means the bile duct is small and harder to enter, so you are more likely to stray into the pancreatic duct during attempts at biliary access. Difficult cannulation, with all its extra attempts and passes. And acinarization on contrast, the visible sign that you have already injured the acini. Picture the patient who pulls several of these together. She has biliary-type pain and a completely normal bilirubin. She has suspected sphincter dysfunction. And her cannulation took six attempts with four inadvertent passes into the pancreatic duct. That patient has stacked nearly every risk factor that exists. She gets indomethacin, aggressive lactated Ringer, and a prophylactic pancreatic duct stent.

8:51There is one risk factor that runs backwards, and it is worth pausing on because it looks wrong. Pre-existing chronic pancreatitis is protective against PEP. The instinct is that a damaged pancreas should be more fragile. It is the opposite. The acinar tissue has already atrophied and fibrosed, so there is far less functional acinar mass left to mount the inflammatory cascade. You cannot inflame parenchyma that is no longer there.

9:16So the safe entry into the duct runs on one discipline. ERCP is a therapy with a real and quantifiable downside, so you earn the right to do it by first proving a non-invasive test cannot answer the question. Then you reduce the downside at every step where you have a lever. You cannulate by guidance rather than by hydraulics, so the duct is found by a wire under control instead of by flooding it with contrast. You stack prophylaxis by mechanism: indomethacin against inflammation, a pancreatic duct stent against outflow obstruction, lactated Ringer for perfusion. And you concentrate the full stack on the patient whose risk factors say the pancreas will react, remembering that a normal bilirubin raises risk rather than lowering it and that a burnt-out chronic pancreas runs the risk backwards.

10:04The next episode takes the other half of doing ERCP safely: deciding who belongs on the table at all. Sphincter of Oddi dysfunction as a landmark trial rewrote it, the pregnant patient who has a radiation-free alternative, and the bleeding, perforation, and infection complications the whole workflow exists to prevent.

10:22For the full chapter, the practice vignettes, and the topic-tagged question bank, head to board pearls dot com. You'll find the rest of the series on Apple Podcasts, Spotify, or wherever you listen to podcasts. That brings us to the end of episode one of seven of chapter twenty nine, and I'll see you in the next one.