Endoscopic Retrograde Cholangiopancreatography (ERCP) can be performed for diagnostic and therapeutic purposes. With the development and widespread dissemination of advanced imaging modalities (i.e. Magnetic resonance cholangiopancreatography (MRCP) and Endoscopic Ultrasound (EUS)), ERCP in the modern era is rarely performed without therapeutic intent. As most ERCP procedures involve the selective cannulation of the common bile duct (CBD) and/or pancreatic duct (PD), failure to effectively cannulate results in global procedural failure, highlighting the importance of successful deep cannulation of the desired duct. As a result, a strong command of techniques aimed at cannulation is important for any advanced or therapeutic endoscopist. In this article, we explore endoscope insertion, orientation, and the fundamentals of selective cannulation of the biliary and pancreatic ducts using various endoscopic techniques.
Following adequate sedation of the patient, a selfretaining mouth guard is placed, and the patient is re-positioned into a prone position, although a small number of centers routinely perform ERCP with the patient supine.1,2 A meta-analysis of 6 studies reporting on 309 supine and 1415 prone ERCPs reported that the pooled technical success rates for completion of ERCP in the supine and prone positions were 89.1 % (95 %CI = 80.9 – 94.0) and 95.6 % (95 %CI = 91.5 – 97.7), respectively. The pooled rates for complications (cardiopulmonary and post-ERCP pancreatitis (PEP)) in the supine position were 37.5 % (95 %CI = 19.1 – 60.3) and 3.5 % (95 %CI = 1.6 – 7.3), respectively.3 The pooled rates for complications (cardiopulmonary and PEP) in the prone position were 41.0 % (95 %CI = 20.9 – 64.8) and 3.9 % (95 %CI = 2.4 – 6.4), respectively. Overall, prone ERCPs appear to have a higher technical success rate with a slightly lower mean duration but a higher number of adverse events.
To perform ERCP, the duodenoscope should be inserted safely into the second portion of the duodenum – the location of the major papilla, also known as the Ampulla of Vater. To this end, it is vital that endoscopists understand normal foregut anatomy as seen with a side viewing instrument and how to insert the duodenoscope into the esophagus, stomach, and duodenum.4 (Figure 1) Patients with altered anatomy may also pose another layer of difficulty but ERCP should only be attempted in these patients after obtaining significant experience in patients with normal anatomy.
As the patient lies in the prone position, esophageal intubation is achieved with the duodenoscope held horizontally and parallel to the examination table with the patient’s neck slightly flexed. Upward tip deflection (backward tension on the large wheel) together with gentle advancement is required to pass through the hypopharynx, although some right or left tip deflection (via backward rotation of the lateral wheel) can often be helpful. The vocal cords are located obliquely upward of the visual field. The duodenoscope should then be gently advanced, passing the vocal cords. The endotracheal tube is often seen clearly in the pharynx if the patient is under general anesthesia. Further, despite the notion that intubation is done blindly, endoscopists can evaluate the oral cavity, epiglottis, vocal cords and the pharynx with the use of side viewing instruments.
As the duodenoscope is advanced to the upper esophageal sphincter (UES), esophageal intubation can proceed with subtle tip deflection combined with gentle pressure. Light downward tip deflection (forward on the large wheel) and gentle torque will enable the endoscopist to perform esophagoscopy if required. Using a neutral position, the duodenoscope can be advanced while examining the walls of the esophagus for landmarks including the Z-line and the transition to the gastric mucosa. Immediately upon entering the stomach, leftward endoscope torque and brief tip extension (large wheel forward) combined with endoscope advancement and air insufflation will allow visualization of the fundus and a portion of the gastric body, giving the endoscopist a clear sense of which direction to proceed in. With the tip of the scope angled downwards, the duodenoscope is then slowly advanced along the greater curvature of the stomach towards the distal stomach.
With further advancement, the duodenoscope will pass the incisura angularis. Should the endoscopist need to examine the cardia, this can be done by upward tip angulation and slow withdrawal and rotation of the duodenoscope to evaluate the lesser curvature. On the other hand, as the tip of the instrument is further angled downwards and advanced, the scope passes the incisura, and the pylorus comes into view. The scope is positioned so that the pylorus is in the center field of vision. However, as the tip of the scope is returned to the neutral position, the pylorus fades from endoscopic view along the bottom of the viewing screen to the point of disappearing: this is referred to as “setting the sun” and alerts the endoscopist that they are in the proper orientation for forthcoming pyloric transit.
It should be noted that, despite its advantages, passage through the stomach can sometimes be difficult, particularly in the prone position.5 To help overcome this, the patient’s right knee can be flexed while the patient’s shoulders are rotated to approximate a left lateral decubitus position and usually facilitates gastric passage and entry into the duodenum. Trainees or inexperienced operators will often over-flex the duodenoscope tip upon entering the stomach, leading to undesired retroflexion in the fundus. Unless the operator in this situation can realize that the source of their difficulties is over-flexion, they will not be able to find the pathway to the distal stomach. This process is referred to as becoming “lost in the fundus.” However, the duodenoscope was designed to easily pass through the stomach, and in most cases the transit from the mouth to the second portion of the duodenum is rapidly accomplished with ease. If repeated attempts to pass the duodenoscope to the small bowel end in failure, it is rarely the fault of the instrument and usually due to operator error. In these cases, the endoscopists should carefully withdraw the instrument, remove excessive air, and attempt to re-intubate again while carefully looking for, and responding to, the various landmarks as outlined above.
Once past the pylorus, advancement to the duodenum requires tip extension (large wheel forward) which provides a global view of the duodenal bulb. This view also enables proper alignment for further movement towards the second portion of the duodenum. With subsequent tip flexion, gentle advancement of the duodenoscope allows the shaft of the instrument to align with the greater curvature of the stomach. This maneuver, which if performed properly will place the duodenoscope into long endoscope the shaft of the duodenoscope to sit on the greater curvature and leaves the tip of the duodenoscope at the second or beginning of the third portion of the duodenum. For most patients, the long endoscope position will enable proper orientation to the major papilla. However, for patients under conscious sedation, the long endoscope position is less tolerated due to gastric distention. In addition, while the long position often gives excellent views of the major papilla, it limits the ability of the duodenoscope to maneuver. As such, most endoscopists routinely transfer to the so-called “short position” via reducing the endoscope to a position wherein the shaft lies flush with the lesser curvature of the stomach. The standard shortening maneuver consists of full rightward deflection, with subsequent locking, of the lateral wheel and upward movement of the large wheel followed by withdrawal and simultaneous clockwise torque applied to the endoscope shaft by the right hand. This shortening maneuver allows the operator to hook the tip of the duodenoscope in the descending duodenum which results in a straighter duodenoscope and brings the papilla The standard shortening maneuver consists of full rightward deflection, with subsequent locking, of the lateral wheel and upward movement of the large wheel followed by withdrawal and simultaneous clockwise torque applied to the endoscope shaft by the right hand. This shortening maneuver allows the operator to hook the tip of the duodenoscope in the descending duodenum which results in a straighter duodenoscope and brings the papilla into full view.
Orientation and Initial Positioning
Once in the second portion of the duodenum, and using the standard shortening maneuver, the endoscopists will usually be able to directly visualize the major papilla without difficulty.5 In the literature, endoscopists have classified the major papilla according to four major types using Haraldsson’s classification: Type 1: “regular papilla” or “classic appearance” most common type with no distinctive features; Type 2: “small papilla,” small, often flat with a diameter not bigger than 3 mm (2 sphincterotome diameter); Type 3: papilla with a large protruding and/or pendulous infundibulum and visible orifice; Type 4: large papilla with multiple overlying folds over the orifice (commonly referred to as a hooded papilla or a Shar-Pei dog papilla).6 Haraldsson’s classification schema is largely used in research studies, and in practice there are many additional varieties of papillary anatomy that can be encountered. Patients can have a single ampullary orifice or clearly separate biliary and pancreatic orifices, and many variants exist.
In rare instances, the papilla may be difficult to identity as it may be concealed behind a fold, distorted, or ablated in patients with malignancy, or indistinct in patients with significant bowel wall edema (such as encountered in patients with acute pancreatitis or severe hypoalbuminemia). In other rare instances, patients may have aberrant anatomy where the papilla is located more proximally, just beyond the apex of the duodenal bulb, or distally, between the second and third portion of the duodenum, the aberrant distal papilla is more common than the proximal one.
The appearance of the major papilla can also be significantly altered if it has undergone prior biliary sphincterotomy, pancreatic sphincterotomy, or dual sphincterotomies. Once identified, a brief evaluation of the ampulla allows for assessment of its type and size, as well as any unusual features which may impede (or facilitate) cannulation or the procedure as a whole (i.e. periampullary diverticula, visibly impacted stones, patulous orifice, prior sphincterotomy, etc.). Most patients with a native ampulla will have a single orifice that provides access to the common channel which bifurcates into the common bile duct and main pancreatic duct (the main pancreatic duct is also known as the duct of Wirsung). A minority of patients will have two separate orifices, however, due to their very close proximity, this may be difficult to discern without close examination.
While the size and shape of the papilla provides useful information, particularly with regards to the angle of the intraduodenal portion of the common bile duct and pancreatic duct, as well as the length of the common channel, defining intra-ampullary anatomy can be challenging even once attempts at cannulation have begun. However, spending adequate time on proper inspection and positioning is beneficial and worthwhile. Furthermore, the endoscopist can thoroughly examine the ampulla from various positions prior to attempting cannulation to get a more complete picture of the local ampullary anatomy, which is often helpful.
Cannulation of the Common Bile Duct
The common bile duct can be cannulated via a variety of endoscopic methods. Some of these methods include:
- Standard catheters
- Sphincterotomes preloaded with guidewires
- Placement of a pancreatic guidewire or stent followed by biliary cannulation
- Access sphincterotomy also known as “precut” sphincterotomy
- Rendezvous techniques that can be performed in combination with EUS-guided biliary access or percutaneous biliary access
The preference for using any one method for cannulation over another (i.e. cannula vs. sphincterotome) is usually a matter of personal choice. However, this decision is partly based on the indication for the procedure, and whether a sphincterotomy is required. Regardless of which device or method is applied in cannulating the biliary tree, several core principles universally apply.
Prior to cannulation, obtaining optimal positioning of the major papilla is vital for success. To this end, when facing the major papilla en face, the biliary orifice will almost always be in the left upper quadrant, corresponding to the 9 o’clock to the 12 o’clock position. It is important to emphasize that the clock face is not with respect to the endoscopic image one sees on a video monitor, but rather with respect to the intraduodenal portion of the common bile duct (i.e., the intraduodenal portion of common bile duct delineates the 12 o’clock position).
When properly oriented and with the ability to interpret the image of the papilla correctly, in this position, the angle of the common bile duct can be extrapolated, at least partly, by evaluating the angle and direction of the intraduodenal portion of the distal common bile duct. By combining this angle with the presumed location of the biliary orifice in the major papilla, attempts at cannulation can proceed in a more orderly and coordinated manner. Using this technical information, one can project an imaginary line into the lumen showing the direction the common bile duct would take if it extended beyond the papilla. The endoscopists should manipulate the duodenoscope and cannulating device to move along this imaginary line when attempting to obtain deep biliary access.
Novice endoscopists will frequently approach the biliary orifice with a catheter or sphincterotome in a manner such that the selected device impacts the duodenal wall at a right angle; this almost universally will result in cannulation failure. Under fluoroscopy, the catheter position can be appreciated, and trainees should be taught to use the information obtained via fluoroscopy to achieve a proper cannulation angle, which is parallel to the intended biliary angle, not perpendicular. By using an upward sweeping motion of the catheter, the device tip mirrors the true direction of the distal common bile duct which very often facilitates successful cannulation.
As the tip of the selected device engages with the biliary orifice at its most superior point, and hopefully, above the septum which separates the pancreatic duct from the common bile duct, direct access can be obtained by applying gentle pressure to the cannulating device and/ or advancing the guidewire. Depending on the device used for cannulation, other maneuvers can be applied such as gentle relaxation of the elevator, a subtle withdrawal of the device and/ or the duodenoscope, and reduced bowing (if a sphincterotome is being used) will facilitate deep access to the common bile duct. Additionally, once the tip of the sphincterotome has been inserted into the papillary orifice, simultaneous unbowing of the sphincterotome along with slowly pulling the scope shaft more tightly along the lesser curvature of the stomach is often a useful technique to achieve selective cannulation of the common bile duct. While these basic techniques are simple in conception, cannulation of the common bile duct is often very challenging, even for well-seasoned endoscopists. There is a very concrete reason that most advanced endoscopy fellowships are a minimum of one year in length: skills such as cannulation are only obtained slowly over a long period of time. Patients may have aberrant papillary or duodenal anatomy which affect the rate of cannulation. Other times, patients may have seemingly normal anatomy, yet achieving successful cannulation may be difficult despite properly performing standard maneuvers. At this time, more advanced techniques may be relied upon to assist in a variety of difficult situations.
Using a Sphincterotome
In modern practice, initial attempts at cannulation are most often performed using a sphincterotome rather than standard biliary catheters. (Figure 2) The primary advantage of using a sphincterotome lies in its ability to be bowed once it passes beyond the tip of the duodenoscope. Sphincterotomes can be bowed at their tips via tension on the same cutting wire that delivers thermal energy via electrocautery to perform sphincterotomy. Tension on this wire achieves the actual mechanical bowing of the device.
Sphincterotomes have a variety of different properties: catheter shaft thickness, degree of bowing, length of cutting wire (ranging in length from 15 to 35 mm), catheter tip diameter (most commonly 0.025″ or 0.035″), length, degree of tapering, number of ports, location of wire exit from the tip of the catheter, etc. Sphincterotome cutting wires typically consist of a single-metal monofilament. The monofilament configuration is commonly used compared to braided filaments
which has a higher risk of inducing more thermal injury to surrounding tissue.7
For example, a sphincterotome with a 30 mm length of cutting wire will often flex to a greater extent than a sphincterotome with a 20 mm length of cutting wire but will need to be more fully advanced into the lumen to allow complete bowing. A sphincterotome with a 20mm cutting wire can bow even when partially still inside the duodenoscope working channel. Likewise, a sphincterotome designed to accommodate a 0.035″ wire is likely to be stiffer than a device for a 0.025″ wire. However, no specific sphincterotome design has universally been shown to be superior. Therefore, selection of a particular sphincterotome is generally based on operator experience and individual preference. Some sphincterotomes have additional features, such as the ability to rotate or to reverse-bow (as might be helpful in a patient with Billroth II anatomy). It should be stressed that for the sphincterotome to fully bow, the cutting wire should be advanced out of the duodenoscope and into the lumen. If the cutting wire remains partially within the duodenoscope channel, this may impede its ability to fully flex, although performing this maneuver can often provide significant advantages during cannulation itself. Bowing with the cutting wire partially in the duodenoscope channel may allow the sphincterotome to flex in a more dynamic fashion when advanced out of the channel and simultaneously applying tension.
Several reports have evaluated outcomes comparing the use of standard biliary catheters and sphincterotomes. Schwacha et al. randomized 100 consecutive patients undergoing ERCP into a standard catheter group and a guidewire sphincterotome group.8 Success rate with regards to biliary cannulation was significantly higher in the guidewire sphincterotome group (84%) than with the standard catheter group (62%) (P = 0.023). Sixteen patients who had cannulation failure with a standard catheter achieved cannulation success using a guidewire sphincterotome, bringing the total success rate in that group to 94%. Rates of post ERCP pancreatitis were similar in both groups. Similar outcomes have been reported in other studies comparing the use of a sphincterotome versus a standard catheter.9,10,11
Importantly, trainees should avoid overly using the sphincterotome in order to line up and cannulate the biliary orifice from afar. Instead, the endoscopists should rely on using upper body movements and the dials of the duodenoscope to achieve optimal positioning and orientation. It should be stressed that it is fully within the standard of care to cannulate with a simple catheter even in the modern era, although few choose to do so in practice. Achieving deep cannulation with a straight catheter takes skill and many endoscopists who trained in earlier eras still practice in this manner.
The term “guidewire cannulation” refers to a set of techniques that allow deep biliary and/or pancreatic access without the use of contrast injection during ERCP. If contrast is used during the cannulation process, and before deep access to the desired duct has been obtained, the term “guidewire cannulation” cannot truly be applied. (Figure 3)
In the event cannulation with a sphincterotome or standard catheter is unsuccessful, a guidewire can be inserted through a sphincterotome or a catheter to aid in achieving biliary cannulation. The guidewire can be inserted using two primary techniques. First, after lining up with what it felt to be an optimal angle for biliary access the accessory is placed into physical contact with the papilla and then the guidewire is advanced. The operator can then see and feel if deep biliary access is obtained. This technique can be referred to as Single Wire Technique #1. (Figure 4)
Alternatively, the sphincterotome can be advanced near the ampulla without making actual physical contact, and the guidewire is advanced across the small “air gap” into contact with the ampulla. The endoscopist can monitor guidewire movement and progress endoscopically and fluoroscopically. If the guidewire is seen to enter the biliary tree, the catheter or sphincterotome can then advance over the wire into the duct itself. This technique can be referred to as Single Wire Technique #2. (Figure 5) Attempts at biliary cannulation can sometimes lead to repeatedly cannulating the pancreatic duct (PD) with the guidewire itself. In these instances, the initial guidewire can be left in the pancreatic duct while the sphincterotome is removed to allow insertion of a second guidewire to be used to reattempt biliary cannulation. The guidewire that remains in the pancreatic duct should preferably be advanced to at least the level of the pancreatic genu to ensure a stable wire position. Deep pancreatic duct access is preferable, but this is not always possible. This technique can be referred to as the Double Wire Technique or the Two Wire Technique. (Figures 6 and 7) The wire in the PD can help to identify the pancreatic orifice, reveal the PD angle, and straighten the papilla as a whole. Additionally, with the initial guidewire in the PD, it is easy to identify fluoroscopically if the second wire is also entering the PD or if biliary cannulation is successful. Several studies have demonstrated that leaving a guidewire in the PD does not generate sufficient hydrostatic pressure to increase the risk of post-ERCP pancreatitis.12-14
Although the 2-wire technique is generally considered safe and effective, one group evaluated the prophylactic effect of placing a PD stent in patients who had undergone PD wire placement as an aid to achieving biliary cannulation, with regards to the incidence of post-ERCP pancreatitis.15 The authors randomized 70 patients who underwent PD wire placement to receive a prophylactic PD stent (a 5 F by 4 cm stent with a single pigtail) or no stent (35 patients in each group). Post-ERCP pancreatitis was less frequently encountered in the stent group (2.9%) versus the no-stent group (23%) (RR: 0.13,
confidence interval: 0.016, 0.95). However, biliary cannulation was achieved in only 80% of patients in the stent group (compared to 94% of patients in the no-stent group). It is somewhat difficult to reconcile the extremely high rate of post-ERCP pancreatitis seen in the group that was not stented, as it is discordant with similar studies.
The inverse of the double guidewire technique is the Reverse Double Wire Technique a.k.a. the Reverse Two Wire Technique. This technique is performed when attempts at pancreatic duct access result in biliary access. This is typically indicated in patients with a variety of disorders which require selective pancreatic duct cannulation such as idiopathic recurrent acute pancreatitis, chronic pancreatitis, pancreatic ductal injuries, pancreatic fistulas, and other indications.16
Similar to the aforementioned techniques, the Reverse Double Wire Technique loads a guidewire through a sphincterotome while cannulation of the common bile duct is attempted and confirmed using selective contrast injection. The sphincterotome is then withdrawn, leaving the guidewire in the common bile duct. This helps to pull and realign the septum more superiorly. It also straightens the pancreatic duct. The sphincterotome is then reloaded with a second guidewire where cannulation of the pancreatic duct is performed, usually with minimal injury to the pancreatic duct or ampulla.17 Despite its reported success, this technique is hardly ever performed due to the risk of pancreatitis. As a result, most published data is limited to case reports.18 Overall, guidewire cannulation is considered effective and safe with a low rate of adverse events. A meta-analysis involving 12 randomized related adverse events.18 The guidewire, in theory, does not generate significant hydrostatic pressure to induce postERCP pancreatitis, although it can occasionally cause injury to the pancreas, particularly if the guidewire accesses and injures a pancreatic duct side branch. However, under fluoroscopy, the
guidewire can easily be identified and repositioned to minimize this risk. It is important to note that the risk of post-ERCP pancreatitis is higher when the guidewire is forcibly advanced into a side branch of the pancreatic duct and causes trauma. Furthermore, the risk of guidewire perforation is very small.19
Recently, repeated single guidewire cannulation was compared to the double wire technique. Laquiere et al. randomized 142 patients; selective bile duct cannulation was achieved in 57/68 patients (84%) in the early double guidewire group and in 37/74 patients (50%) in the repeated single guidewire group within 10 minutes (relative risk 1.34; 95% confidence interval 1.08-6.18; P < 0.001). The overall final selective bile duct cannulation rate was 99.3%. The time to access the CBD was shorter using the double guidewire technique (6.0 vs. 10.4 minutes; P = 0.002). Mild PEP was not observed more frequently in the double guidewire group than in the repeated single guidewire group, further demonstrating the safety of wire entrance into the pancreatic duct. While the current data show a higher cannulation rate, within a shorter period, ultimately, selecting between both techniques is a matter of endoscopist preference. However, when challenged by difficult cannulations, the endoscopists should be versatile with an extended armamentarium of advanced endoscopic techniques.
Pancreatic Duct Stent Placement
If attempts at biliary cannulation are unsuccessful, endoscopists can consider placement of a pancreatic stent. (Figure 8) This approach has several benefits. First, pancreatic stents reduce the risk of the patient developing post-ERCP pancreatitis by decompressing main and side duct branches of the pancreas. Second, placement of a pancreatic stent reduces the risk of the pancreatic duct being repeatedly cannulated by the guidewire during ongoing cannulation attempts. Third, by having a pancreatic stent in place, the endoscopists can key-in on the angle of the pancreatic duct and, by extrapolation, the common bile duct. This later point is most beneficial in cases of distorted or altered anatomy.
Precut biliary sphincterotomy and associated techniques
The term “precut” refers to the action of performing a sphincterotomy (or “cut”) prior to obtaining deep biliary access (the “pre-”) with a guidewire. The term is often used, both in print and in speech, interchangeably with the term “needleknife sphincterotomy.” In fact, the term “precut” refers rather to a group of high-risk techniques to obtain biliary access if standard maneuvers are unsuccessful. These techniques are collectively termed access sphincterotomy techniques and carry a greater risk of complications. A meta-analysis of seven clinical trials with a total of 1039 patients compared early pre-cut biliary orifice and moving in a cephalad direction. Needle knife sphincterotomy is typically performed when biliary cannulation attempts using less invasive techniques have been tried without success and should be regarded as a relatively highrisk procedure. Because the endoscopist is cutting into the papilla and the duodenal wall without the benefit of a guidewire sphincterotomy vs. persistent attempts at cannulation by standard approach.22 The overall cannulation rate was 90% in the pre-cut sphincterotomy vs. 86.3% in the persistent attempts group (OR = 1.98; 95%CI: 0.70-5.65). The risk of post-ERCP pancreatitis (PEP) was not different between the two groups (3.9% in the pre-cut sphincterotomy vs. 6.1% in the persistent attempts group, OR = 0.58, 95%CI: 0.32-1.05). Similarly, there was no statistically significant difference between the groups for overall complication rate including PEP, cholangitis, bleeding, and perforation (6.2% vs. 6.9%, OR = 0.85, 95%CI: 0.51-1.41).
Needle-knife sphincterotomy refers to the use of a catheter capable of delivering electrosurgical current through a wire to directly dissect the major papilla and the intraduodenal portion of the common bile duct to obtain biliary ductal access. (Figure 9) Needle knife sphincterotomy is rarely used to obtain pancreatic access, although it is possible. The standard needle knife design incorporates a bare wire that can be extended through a modified straight biliary cannula. These devices do not have the capability to bow as do most sphincterotomes. The most common way this device is used involves beginning the sphincterotomy at the level of the in the CBD, the true orientation of the duct is, at least in part, unknown during the needle knife sphincterotomy. It should be noted that complication rates from needle-knife sphincterotomy may not necessarily decrease based on the experience of endoscopists. Following 253 consecutive patients undergoing needle knife sphincterotomy by a single endoscopist over a 7.5-year interval, success rate remained high (with the success rate the highest at the end of the study), and overall complication rates (and complication severity) remained similar throughout the study.23 Overall complication rates ranged between 12% and 20% throughout the time blocks of the study and included pancreatitis, bleeding, perforation, among others.
Still, other studies have shown that needle-knife sphincterotomy is not necessarily associated with higher rates of post ERCP pancreatitis. A study of two prospective trials of native papilla cannulation evaluated 732 total patients and included 94 patients undergoing needle-knife sphincterotomy.24 The authors found that an increased number of attempts at cannulation of the papilla were independently associated with post-ERCP pancreatitis. Needleknife sphincterotomy was not an independent predictor of post-ERCP pancreatitis.
Another prospective study also concluded that higher rates of post-ERCP pancreatitis are likely associated with increased number of attempts to cannulate the papilla and were not associated with the precut sphincterotomy itself. This study evaluated patients undergoing ERCP where the endoscopist was unsuccessful at achieving biliary cannulation after 10 minutes.25 Patients were then randomized to an immediate needle-knife sphincterotomy versus a late-access group in which cannulation was then attempted for another 10 minutes (after that point the endoscopist could either perform a precut sphincterotomy or continue attempts at cannulation). The overall incidence of complications between the 2 groups was similar; however, the rate of pancreatitis was higher in the late-access group (14.9% vs. 2.6%, P = 0.008). These studies suggest that higher rates of postERCP pancreatitis are associated with repeated attempts to cannulate the papilla and may not be associated with needle-knife sphincterotomy in and of itself. Some endoscopists may elect to perform prophylactic pancreatic stent placement prior to performing needle knife sphincterotomy in order to use the stent as a guide for the incision and in an attempt to reduce the rate and severity of post ERCP pancreatitis (PEP). A meta-analysis demonstrated that prophylactic pancreatic stent placement significantly reduced the rate of post ERCP pancreatitis. However, if stent placement fails then pancreatitis rates increased by 35-66% in select high risk patients.26
Precut fistulotomy a.k.a. needle knife fistulotomy
Another variation of the needle-knife sphincterotomy technique involves beginning the incision above the level of the ampullary orifice and attempting to cut directly into the CBD via the creation of a biliary fistula; this approach is referred to as precut fistulotomy a.k.a. needle knife fistulotomy. Once the CBD is accessed, a standard sphincterotome can be used to extend the sphincterotomy, if needed, recognizing that a fistulotomy approach may result in a smaller sphincterotomy size overall. A meta-analysis of four prospective studies and three randomized trials showed that using this technique the pooled cannulation success rate was 95.7% (95% CI, 83.1–99.0, P < 0.001), and the rate of post-ERCP pancreatitis was 1.5 % (95% CI, 0.6–3.9, P < 0.001). When compared with conventional wireguided technique, the odds of developing postERCP pancreatitis with pre-cut fistulotomy were 0.22 (95% CI, 0.04–1.04, P = 0.06).
Endoscopic transpancreatic papillary septotomy
The aim of transpancreatic papillary septotomy is to incise the septum between the pancreatic duct and bile duct to expose the bile duct orifice. A standard pull- or traction-type sphincterotome is used with its tip located in the pancreatic duct, but with the endoscope and the sphincterotome oriented for a biliary sphincterotomy. This allows the cut to begin in the pancreatic duct but to traverse the septum between this structure and the CBD, ultimately resulting in biliary access. The technique is typically employed when only pancreatic duct access is obtained during attempts at securing deep biliary access.
In technical terms, transpancreatic sphincterotomy may offer better control of the incision’s depth facilitated by the progressive withdrawal and lateral tension applied to the sphincterotome, thus targeting the common bile duct toward the 11 o’clock position. The intention is to cut across the septum and into the CBD and expose the lumen.27 Endoscopic transpancreatic papillary septotomy is not widely performed at the present time as it is unclear if it offers any significant benefit over standard needle-knife sphincterotomy. Some have concerns about causing pancreatitis or pancreatic ductal injury as well. To this end, results with this technique have been mixed with varying rates of success. A randomized trial comparing transpancreatic biliary septotomy versus the double-guidewire than the two guidewire technique (69.7 % [69/99]; P = 0.01), though similar rates of post procedure pancreatitis (13.5 % vs. 16.2%, P=0.69, respectively).28 The success rates seen with the two wire technique in this study are exceptionally low, making this study somewhat of an outlier and the results difficult to interpret.
Recently, a network meta analysis comparing the efficacy of different strategies for difficult biliary cannulation supported the use of transpancreatic sphincterotomy over persistence with standard cannulation techniques (risk ratio [RR], 1.29; 95% confidence interval [CI], 1.05-1.59) and over any other adjunctive intervention (RR, 1.21 [95% CI, 1.01-1.44] vs. pancreatic guidewire-assisted technique, RR, 1.19 [95% CI, 1.01-1.43] vs. early needle-knife techniques, RR, 1.47 [95% CI, 1.032.10] vs. pancreatic stent-assisted technique) for increasing the success rate of biliary cannulation.29 In addition, both early needle-knife techniques and transpancreatic sphincterotomy led to lower PEP rates as compared with pancreatic guidewireassisted technique (RR, .49 [95% CI, .23-.99] and .53 [95% CI, .30-.92], respectively).
Despite the current data, transpancreatic sphincterotomy is currently used on a limited basis. However, this technique should be considered when attempting difficult biliary cannulation.
Pancreatic duct cannulation
To achieve pancreatic duct cannulation similar techniques and concepts can be applied. In most cases, guidewire cannulation of the pancreatic duct can easily be performed using many of the techniques previously described in this article.
The ideal distance of the duodenoscope from the major papilla is the “middle distance” (2-3 cm). The endoscope should be at or slightly above or at the level of major papilla (as opposed to the bile duct where a “below” the papilla position is favorable). Typically, pancreatic cannulation is obtained with the endoscope oriented more toward the anterior aspect of the duodenum, using less bow on the sphincterotome, and with the lateral ratchet more leftward (anterior) than when performing biliary cannulation. A flatter angle between the sphincterotome and the duodenal wall is often desirable as well, and this can be identified on endoscopic and fluoroscopic views. Guidewire cannulation is the technique least likely to produce hydrostatic overpressure in the pancreatic duct. This may minimize the risk of postERCP pancreatitis and should be considered for pancreatic cannulation, if possible. Dye injection, it should be stated, is not contraindicated and is often helpful in some cases, especially with unusual pancreatic ductal anatomy (pancreas divisum, an ansa loop in the pancreatic head, etc.).
In cases where the anatomy of the pancreatic duct has been altered or the duct is difficult to cannulate, the Reverse Double Wire Technique or the Reverse Two Wire Technique (described above) may be helpful. Other advanced techniques, such as needle knife sphincterotomy, are rarely required for pancreatic duct access but can be considered on a case-by-case basis.
In patients with prior biliary sphincterotomy, the pancreatic duct orifice can sometimes be identified as a separate orifice. In these patients, the pancreatic orifice is seen as a separate opening located below and to the right (as the endoscopist faces the papilla) of the biliary sphincterotomy. However, in some cases it may be more difficult to identify. The orifice may be located within the prior biliary sphincterotomy in a patient with a longcombined sphincter (>10 mm). The endoscopist may find it beneficial to closely examine residual ampullary structures such as mucosal folds before attempting pancreatic cannulation, as the pancreatic orifice may be hidden.
The success of an ERCP is dependent on achieving successful cannulation of the desired duct. Anatomical assessment and selection of the proper cannulation technique is critical not only for procedure success but also to reduce the risk of serious adverse events, most notably post-ERCP pancreatitis. Cannulation is a skill that can take a significant amount of time to master; this often requires years of training and practice. Knowledge of available techniques is critical, as one can never know in advance which maneuvers and devices will be required to complete any given ERCP.
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