Key points

Introduction

ERCP was originally developed almost half a century ago as a diagnostic tool for pancreaticobiliary disorders. It has been proved to be an effective procedure over the years, not without associated complications. With the development of noninvasive and minimally invasive diagnostic alternatives such as magnetic resonance cholangiopancreatography and endoscopic ultrasonography (EUS), ERCP has evolved from being primarily a diagnostic modality to almost entirely a therapeutic procedure. Selective deep cannulation of the common bile duct (CBD) or PD with guidewire access is required for successful therapeutic interventions. At times, this can be difficult for even the most experienced endoscopists. Many advanced techniques have been developed to overcome the difficulties encountered when attempting biliary cannulation.

Introduction

ERCP was originally developed almost half a century ago as a diagnostic tool for pancreaticobiliary disorders. It has been proved to be an effective procedure over the years, not without associated complications. With the development of noninvasive and minimally invasive diagnostic alternatives such as magnetic resonance cholangiopancreatography and endoscopic ultrasonography (EUS), ERCP has evolved from being primarily a diagnostic modality to almost entirely a therapeutic procedure. Selective deep cannulation of the common bile duct (CBD) or PD with guidewire access is required for successful therapeutic interventions. At times, this can be difficult for even the most experienced endoscopists. Many advanced techniques have been developed to overcome the difficulties encountered when attempting biliary cannulation.

Guidewire-assisted cannulation

Guidewire-assisted cannulation has quickly become the standard technique to improve biliary cannulation with the intent of reducing complications. The technique involves cannulating the papilla with gentle probing of a guidewire preloaded in a papillotome. The guidewire is then advanced up the duct without injecting contrast; this can be done either by initially advancing the guidewire out of the papillotome a few millimeters before commencing cannulation or by engaging the tip of the papillotome in the papillary orifice before advancing the guidewire. The former is preferred when there is a small punctum or a stenotic papillary orifice, but the latter is a much more reliable approach, as seating the tip of the papillotome in the mucosal orifice provides a stable platform to begin wire manipulation. Manipulation of the guidewire can be handled by an assistant or the endoscopist. The choice is highly personal depending in large part on the experience of the assistant and the prior experience of working together on a large number of cases. Most endoscopists prefer to control the wire by gently probing in a staccato fashion to advance through the sphincter orifice and up the CBD. A straight-tipped wire is best to start with, and the author prefers the 0.025-in-caliber wire, which has a malleable tip with sufficient stiffness along the body of the wire for pushability. Buckling of the wire within a few centimeters of advancement may be due to passage into the cystic duct takeoff in the CBD or a branch duct in the PD. When in doubt, the position of the guidewire can be confirmed with fluoroscopy by injecting a small amount of contrast before advancing the papillotome deeply into the duct.

Several early studies found that guidewire-assisted cannulation technique increased the percentage of successful cannulations while decreasing the risk of PEP. Postulated mechanisms for improved outcomes included less papillary trauma and edema, as well as avoidance of contrast, which may increase hydrostatic pressure within the duct, induce an inflammatory response to the chemical constituents, or introduce bacteria into the PD. A recent meta-analysis of 12 randomized controls trials (RCTs) showed that guidewire-assisted cannulation significantly reduced PEP compared with traditional contrast-assisted cannulation technique (relative risk [RR], 0.51; 95% confidence interval [CI], 0.32–0.82). In addition, guidewire-assisted cannulation technique was associated with greater primary cannulation success (RR, 1.07; 95% CI, 1.00–1.15), fewer precut sphincterotomies (RR, 0.75; 95% CI, 0.60–0.95), and no increase in other ERCP-related complications.

Unfortunately, guidewire-assisted cannulation has not been a panacea, as newer studies have not substantiated this analysis of earlier trials. A prospective randomized multicenter study involving 400 consecutive patients compared wire-guided cannulation with traditional contrast-guided cannulation. Although wire-guided cannulation was found to significantly shorten cannulation and fluoroscopy times, it did not decrease the incidence of PEP. Another prospective comparative-intervention single-center study of 1249 patients found no significant difference in the rate or severity of PEP between the guidewire and contrast-assisted groups. In fact, there was actually a trend toward increased risk of pancreatitis in the guidewire-assisted group, but the risk of severe pancreatitis occurred more often in the contrast injection group. No significant difference in the characteristics of the 2 groups, including prophylactic pancreatic stenting, was found to explain this trend. A prospective multicenter randomized controlled crossover trial of 322 patients also failed to show any difference in biliary cannulation success or PEP ( P = .40 and .95).

Given that guidewire cannulation has its own risks of false passage, intramural dissection, pancreatic ductal injury, and perforation, one must advance the guidewire carefully, recognizing the potential traumatic impact possible. Currently available guidewires have a soft, hydrophilic leading segment to facilitate passage through a tortuous common channel and minimize trauma. In the author’s experience, using a 0.025-in-caliber guidewire with a soft, tapered hydrophilic tip and a stiff shaft may improve cannulation success and decrease complications, although no large studies have directly addressed this. Regardless of the guidewire used, placement of a pancreatic stent for PEP prophylaxis should be considered after multiple guidewire insertions into the PD in high-risk patients.

Pancreatic duct techniques

In situations when the CBD is unable to be cannulated with standard techniques, cannulation of the PD can often be achieved more easily. When the guidewire is inadvertently advanced into the PD, it can be left in the duct to assist through a variety of mechanisms. The wire may help to stabilize the scope position, anchor and straighten the PD and common channel, open up a stenotic papilla, separate the biliary and pancreatic orifices, identify the pancreatic axis, direct a precut incision, and partially occlude the pancreatic orifice to deflect the guidewire into the CBD. Initial studies of double-wire technique were promising. A randomized trial of 53 patients in whom biliary cannulation failed after 10 minutes showed that double-wire technique achieved successful cannulation in 93% of patients as opposed to 58% in the standard biliary technique group. A similar efficacy of 94% successful biliary cannulation was achieved by double guidewire technique in another randomized trial of 70 patients. No differences in complications were observed in either study.

Prolonged manipulation of the wire in the PD is a well-recognized risk factor for PEP. It was thought that early use of the double-guidewire technique may decrease the number of PD cannulations and thus the incidence of PEP as well. However, a single-center cohort study of 50 patients and a multicenter prospective RCT that included 274 patients failed to show a decrease in the rate of PEP. Possible explanations include the degree of guidewire manipulation with the wire in the PD as well as possible penetration or perforation of side branches during cannulation. With the wire already in the PD, it is easy to protect against complications by placing a narrow-caliber pancreatic stent (3F–5F). The efficacy of a prophylactic pancreatic stent in this situation has been demonstrated in randomized control trials.

A variation on the double-guidewire cannulation technique involves placing the pancreatic stent immediately after cannulating the PD. This technique allows for better identification of the pancreatic axis and total occlusion of the PD, which then allows for deflection of the guidewire into the CBD. A randomized control trial of difficult biliary cannulation in 87 patients demonstrated a higher rate of successful biliary cannulation in the pancreatic stent-assisted cannulation group than in the double-wire technique group (91% vs 67%). However, more precut sphincterotomies were performed with the pancreatic stent-assisted technique (26% vs 10%), likely accounting for the higher cannulation success. A retrospective study of 76 patients showed similar efficacy (93% success, 21% requiring precut). The placement of a pancreatic stent immediately, although helpful for precut, can often compress the biliary orifice and make standard approaches more difficult. The author only places a pancreatic stent early to protect the PD for intended precut sphincterotomy.

Precut sphincterotomy

Precut sphincterotomy was first described by Siegel in 1980 as a technique to create a controlled incision to facilitate biliary cannulation when standard attempts have failed. The term has now come to encompass a broad range of technical variations on the original precut technique as well. The decision to use precut sphincterotomy can depend on multiple factors, including the indication, skill and experience of the endoscopist, and anatomy. The technique is most helpful in unusual or distorted anatomy of the papilla, such as cases of malignancy, impacted stone, or humpback anatomic configuration. Precut sphincterotomy is also useful in patients with altered anatomy status post Billroth II or Roux-en-Y anastomosis. Because the papilla is approached from below in these patients, standard sphincterotomes do not align along the biliary axis, which is now in the 5-o’clock position. Use of a plastic cap, when balloon enteroscopy-assisted ERCP is required due to a long afferent limb, can be helpful in positioning and stabilizing the biliary orifice for cannulation.

The most commonly applied precut technique is precut papillotomy (PP), which involves starting the incision from the upper rim or lip of the papillary orifice and extending the cut cephalad in the biliary axis. This technique can be accomplished with various devices but is most frequently performed freehand with a needle knife and commonly referred to as needle-knife sphincterotomy (NKS).

Precut fistulotomy (PF) is another precut technique that involves creating an incision usually at the apex of the bulge created by the intraduodenal bile duct and cutting downward into a dilated duct or to the surface of an impacted stone. PF is theoretically safer as it spares the pancreatic orifice from thermal injury and may decrease the incidence of PEP, but it is predicated on having a dilated intraduodenal segment of bile duct. Lithotripsy was required more often when PF was performed for stone disease versus PP, presumably related to a smaller sphincterotomy, which is not extended to the papillary orifice.

Once the CBD has been cannulated, a standard sphincterotome is generally used to extend the sphincterotomy as needed. A small precut incision can also be expanded with a dilation balloon to facilitate the removal of large CBD stones. The balloon diameter is chosen to match the size of the stone but not larger than the native duct. Recent studies and meta-analyses have shown balloon dilation after initial sphincterotomy to be as effective as sphincterotomy alone and to decrease the need for mechanical lithotripsy. The balloon dilation technique is discussed further in the article by Dr Sherman elsewhere in this issue.

For many years, precut sphincterotomy was considered high risk and only to be done by experts as a last resort after multiple attempts at standard cannulation had failed. The complication rates were high, up to one-third of patients, with increases seen in bleeding, perforation, and pancreatitis. However, the incidence of severe pancreatitis and overall complications was reduced when precut sphincterotomy was performed with prophylactic pancreatic stent placement.

The negative outcomes in early studies may have been related to the absence of prophylactic measures and limited experience with the technique. More recent studies have demonstrated that precut sphincterotomy is a safe, time-saving, and effective technique. A meta-analysis of 6 prospective trials that included 959 patients actually showed that precut (PP and PF) significantly reduced the risk of PEP as well as a trend toward increased biliary cannulation success.

It has been suggested that switching to precut earlier in the procedure may help avoid PEP because the prolonged and repeated attempts at cannulation that typically precede this advanced technique may be responsible for many of the reported complications. A retrospective analysis of 2004 patients undergoing ERCP for choledocholithiasis at a single center showed no significant difference in rates of PEP when less than 10 attempts at cannulation were made compared with precut. A meta-analysis of 6 RCTs that included 966 patients undergoing early precut sphincterotomy using various techniques (PP, PF, Erlangen PP) versus persistent attempts at cannulation using standard techniques has been reported. Overall biliary cannulation rates and total adverse event rates were similar. However, when pancreatitis alone was considered, a significantly lower PEP rate was seen in the early precut group (2.5% vs 5.3%; odds ratio [OR], 0.47; 95% CI, 0.24–0.91). An updated meta-analysis of 7 RCTs with 1039 patients showed a trend toward higher rates of cannulations in the early precut group than in the traditional cannulation group (90% vs 86.3%; OR, 1.98; 95% CI, 0.70–5.65) and a trend toward lower rates of PEP (3.9% vs 6.1%; OR, 0.58; 95% CI, 0.32–1.05), with similar overall complication rates (6.2% vs 6.9%; OR, 0.85; 95% CI, 0.51–1.41).

Even if biliary cannulation fails after initial precut sphincterotomy, repeating the ERCP after 2 days (allowing the inflammation and edema from manipulation of the papilla to resolve) may be an option if the patient’s condition permits. Reports of 2 series of patients found that repeat ERCP within 2 to 7 days after failed initial precut sphincterotomy was ultimately successful 82% to 100% of the time, thus justifying a repeat ERCP before considering more invasive approaches such as EUS-guided or percutaneous biliary access.

The initial fears regarding precut sphincterotomy have largely been dispelled by a more thorough understanding of the indications, the utility of a pancreatic stent, greater respect for the risks, and better understanding of the anatomic features. Persistance versus precut as a choice is not clear cut but much more a decision based on cannulation skills and familiarity with needle knife principles, with the final decision best made based on anatomic considerations as to what is favorable for precut or not.

Transpancreatic septotomy

Transpancreatic septotomy (TPS) is a precut technique of cutting through the septum that separates the terminal end of the CBD and PD. Goff first described the technique in 1995 using a standard traction sphincterotome inserted superficially into the PD. The sphincterotome is then oriented in the 11-o’clock position, and an incision is made to expose the biliary orifice or the bile duct itself. Once the ductal septum is cut, biliary cannulation can be reattempted. Advantages of the technique include not having to exchange catheters for a needle-knife device and the ability to better control the depth of incision with a traction-type sphincterotome than with a free-hand needle knife. Retrospective and prospective series have demonstrated the relative efficacy and safety of TPS, although increased rates of PEP have been seen due to direct thermal injury to the pancreatic orifice. Placing a PD stent after TPS has been shown to reduce the incidence of PEP.

A prospective multicenter study of 216 patients comparing TPS and NKS found no significant difference in the initial and eventual success rates or the incidence of PEP and overall complications. A recent single-center prospective RCT of 149 patients showed TPS to have a higher biliary cannulation rate (96% vs 84%, P = .018), faster cannulation time (193 vs 485 seconds, P <.001), and similar incidence of complications as NKS. Another single-center prospective RCT of 71 patients compared TPS with the double-guidewire technique. Biliary cannulation rates and the time to cannulate were similar, but the overall incidence of PEP was significantly lower in the TPS group (11% vs 38%, P <.01).

TPS is a viable option, although not commonly used in North America. The success of this approach critically depends on the appropriate cutting current to minimize any coagulation effect and to avoid a deeper cut to prevent pancreatic parenchymal insult. A prophylactic pancreatic stent should be considered after TPS, especially in high-risk patients.

Additional variations on precut

A variation on the PP technique involves using a specialized noseless Erlangen-type traction sphincterotome, which takes its name from the birthplace of endoscopic sphincterotomy, Erlangen, Germany. Using a traction sphincterotome is thought to limit complications by allowing better control of the depth of incision compared with a free-hand needle-knife device, although limited data exist to support this hypothesis.

Intramucosal incision is another variation of the PP technique, first described by Burdick in 2002, that takes advantage of the inadvertent formation of a false tract. Sometimes during bowing of the sphincterotome/cannula and the use of guidewire-facilitated cannulation, inadvertent formation of a false passage occurs in the 11-o’clock direction. The tip of the wire or the sphincterotome punctures the superior aspect of the mucosal canal of the papillary orifice and then tracks submucosally and emerges out of the roof of the papilla. This event is generally considered undesirable; however, Burdick used this false tract formation as an opportunity to achieve selective biliary cannulation by applying an intramucosal incision technique whereby the mucosa is laid open and the pseudotract is incised with the sphincterotome, thus improving exposure of the biliary duct orifice. This technique has some conceptual similarities to TPS, in which a mucosal cut is responsible in large part for improving access to the sphincter lumen. The safety and efficacy of intramucosal incision have been demonstrated in retrospective series.