Advanced Cannulation Technique and Precut

For most ERCP endoscopists, the greatest hurdle to a successful procedure is deep cannulation of the bile duct. This article explores basic cannulation technique, then reviews a variety of instruments and techniques designed to increase the average endoscopist’s success rate. Expert ERCP endoscopists have a few favorite techniques that have proved reliable over time. The most frequently used ones are highlighted in this review.

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It probably takes 1000 ERCPs to become skilled at cannulation, and several thousand more to become an expert.
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The expert ERCP endoscopist must be able to innovate and adapt his or her technique to deal with unexpected and unfamiliar anatomy.
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ERCP has evolved into an almost entirely therapeutic modality, increasing the technical difficulty and requiring skill with guide wires, catheters, stents, and so forth.
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The “pull” papillotome has become the primary tool for ERCP cannulation.
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Needle knife papillotomy (NKP) should be taught to all serious students of ERCP, and no longer regarded as a high-risk procedure for experts only.
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The epidemic of obesity in the United States and the resulting explosion of bariatric (weight loss) surgery has created a population of patients whose bile ducts are endoscopically inaccessible using standard duodenoscopes and catheters.

Key Points

Introduction

For most ERCP endoscopists, the greatest hurdle to a successful procedure is deep cannulation of the bile duct. It is like a potential energy “hump.” What separates expert ERCP endoscopists from lesser ones is their ability to reliably cannulate the bile duct with the minimum of trauma to the duodenal papilla. There is a long learning curve involved, such is the variability in papillary and local gastrointestinal (GI) anatomy. This article explores basic cannulation technique, then reviews a variety of instruments and techniques designed to increase the average endoscopist’s success rate ( Boxes 1 and 2 ). Many of these techniques require access to the pancreatic duct (PD) for placement of a guide wire and stenting. Other techniques use precutting or needle knife papillotomy (NKP), “free hand,” or down on to a guide wire or stent. It is the author’s opinion that any sufficiency skilled and experienced ERCP endoscopist can overcome the great majority of local anatomic difficulties to obtain deep cannulation. There are many variables to consider when addressing success rates for biliary cannulation, including the training and experience of the operator, the technique used (eg, with or without precut papillotomy), local anatomic issues (eg, diverticula), familiarity with adjunctive techniques, such as cannulation over a stent or a guide wire, and so forth. The secret to being a skilled ERCP endoscopist is mastering a variety of techniques for deep access to the duct of choice. Prominent papillas, small papillas, upside-down papillas (in post-Billroth II gastrectomy afferent limbs), papillas inside diverticula, and those at the end of long Roux-en Y limbs all require a plan of attack and techniques tailored to the situation. The early ERCP experts could do a lot with a few tools, but their modern successors have many more accessories and techniques at their disposal. Professional golfers are permitted up to 14 clubs in their bags, but they tend to favor certain ones. Similarly, expert ERCP endoscopists have a few favorite techniques that have proved reliable over time. The most frequently used ones are highlighted in this review.

Box 1

Catheters
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Standard
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Tapered
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Steerable
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Cremer

Guide wires
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Coated and uncoated (nitinol, hybrid, hydrophilic)

Papillotomes
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Standard (“pull”-type)
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Needle knife
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Shark-fin
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Steerable
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Billroth-II

Accessories for ERCP

Box 2

Placement of stent or guide wire in the PD to facilitate biliary cannulation
Precut papillotomy
NKP: “free-hand,” fistulotomy, over-a-stent (or a guide wire)
Trans-septal (transpancreatic) sphincterotomy (Goff procedure)
Endoscopic scissors
Endoscopic dissection (cotton tip)
Papillectomy/ampullectomy
Needle tip (Cremer) catheter
Endoscopic ultrasound (EUS)-guided

Adjunctive techniques for biliary and PD access

As Freeman and Guda have pointed out, defining and measuring success at cannulation is problematic. How successful can a cannulation be considered if it is followed by a serious, even life-threatening complication, such as perforation or necrotizing acute pancreatitis? Some clinical situations are recognized to carry a high risk of complications (eg, ERCP in suspected sphincter of Oddi dysfunction), whereas others are considered relatively safe (eg, bile duct stone removal in elderly patients with dilated ducts). The definition of success must take into account “intention to treat.” Prior manipulation of the orifice, such as sphincterotomy, typically renders cannulation easier than instrumenting a virgin papilla. The perceived technical difficulty of ERCP is also a factor: Schutz and Abbott proposed a 5-point scale of ERCP difficulty that has been useful to investigators looking at success and failure rates for this procedure. Perhaps the greatest value of such a scoring scale is that it makes novice endoscopists think twice before taking on challenging cases. In the past 20 years, ERCP has gone from being a largely diagnostic modality to an almost exclusively therapeutic one. The quality of modern abdominal imaging, by computed tomography (CT), magnetic resonance imaging (MRI), and endoscopic ultrasound (EUS) is such that a lot of the guesswork has gone out of investigating biliary and pancreatic disease. In modern ERCP practice, there should be few surprises for the endoscopist, who can and should use these high-resolution imaging techniques to map out the relevant anatomy and help plan the appropriate therapeutic intervention ahead of time. The risk of complications of ERCP, small as it may be in experienced hands, cannot be ignored in the interests of a “fishing trip.” The comfort and safety of the patient must always be the top priority of the endoscopist.

Straight catheters versus papillotomes

In the early days of ERCP, endoscopists started the procedure with a straight catheter. Indeed, I used to require that my trainees become adept at cannulation with a straight catheter before advancing to a papillotome, which is now most ERCP endoscopists’ preferred first catheter. Deep cannulation of the bile duct with a straight catheter requires accurate positioning from below the papilla to achieve the necessary axis; this is still a useful skill to attain. The fiscal reality of modern ERCP reimbursement no longer allows us the “luxury” of using multiple catheters, however: we now choose the one most likely to succeed. Some of the straight ERCP catheters are thin (tapered) and potentially traumatic to the papilla and ducts. I rarely use a straight catheter for biliary access. Papillotomes have the significant advantage of offering a variable angle for cannulation and subsequent manipulation to achieve deep access to the bile duct. Papillotomes have been developed that are “steerable,” allowing the tip to be rotated in an arc. Some endoscopists find these helpful, although experienced endoscopists have other ways to alter the tip direction without a steering mechanism. “Grooming” the papillotome tip, usually by twisting it counterclockwise, is a time-honored method of improving the cannulation axis, but this permanently deforms the catheter, which can prove problematic later in the procedure.

Straight catheters versus papillotomes

In the early days of ERCP, endoscopists started the procedure with a straight catheter. Indeed, I used to require that my trainees become adept at cannulation with a straight catheter before advancing to a papillotome, which is now most ERCP endoscopists’ preferred first catheter. Deep cannulation of the bile duct with a straight catheter requires accurate positioning from below the papilla to achieve the necessary axis; this is still a useful skill to attain. The fiscal reality of modern ERCP reimbursement no longer allows us the “luxury” of using multiple catheters, however: we now choose the one most likely to succeed. Some of the straight ERCP catheters are thin (tapered) and potentially traumatic to the papilla and ducts. I rarely use a straight catheter for biliary access. Papillotomes have the significant advantage of offering a variable angle for cannulation and subsequent manipulation to achieve deep access to the bile duct. Papillotomes have been developed that are “steerable,” allowing the tip to be rotated in an arc. Some endoscopists find these helpful, although experienced endoscopists have other ways to alter the tip direction without a steering mechanism. “Grooming” the papillotome tip, usually by twisting it counterclockwise, is a time-honored method of improving the cannulation axis, but this permanently deforms the catheter, which can prove problematic later in the procedure.

Standard cannulation technique

As a trainee, it is embarrassing to spend a long time struggling to cannulate, then have your teacher achieve deep cannulation on his or her first attempt. How do experts make this look easy? In ERCP, as with most hand-eye coordination skills, there is no substitute for experience. It probably takes at least 1000 cannulations to become truly comfortable with the technique, and several thousand more to become expert. Not every endoscopist has the spatial orientation and hand-eye coordination to reach this level. Most experienced ERCP teachers have come across trainees who fail to acquire the necessary skills even after many procedures. These novices are understandably frustrated with their lack of progress, and often blame their teachers for it. But without a “feel” for the 3-dimensional environment in which the ERCP endoscopist has to work, the attainment of expertise is unlikely. These individuals are rarely willing to acknowledge that ERCP is not for them, and continue to perform these procedures, often in the community where their annual volume of cases is low. This is a significant problem in the United States, where small numbers of cases done in training are often accepted for ERCP-credentialing purposes, and there is rarely a requirement to show maintenance of skills on periodic basis thereafter.

Every trainee who comes out of a gastroenterology fellowship intending to perform ERCP without further mentoring should be adept at selective cannulation. The growing recognition over the past decade that prophylactic stenting of the PD greatly reduces the risk of severe post-ERCP pancreatitis makes the ability to reliably cannulate the duct of choice mandatory. The task of cannulation requires an organized approach. First, do not be in a hurry: take a good look at the main duodenal papilla and decide what the bile duct and PD axes are likely to be. This requires an unobstructed view, and control of duodenal motility by pharmacologic means if necessary. Are there any clues, like a biliary orifice gaping open, or a little trickle of bile, to guide your way? Has there been prior manipulation of the papilla (eg, endoscopic sphincterotomy) that will make cannulation easy, or easier? If the patient has had a prior cholecystectomy, check for the presence of a choledochoduodenal fistula about an inch above the papilla. This is the weakest point in the extrahepatic bile duct wall, which is sometimes perforated when surgeons probe the bile duct with dilators during cholecystectomy. The surgeon thinks that he or she has passed the probe through the papilla into the duodenum, but, in fact, a suprapapillary fistula ( Fig. 1 ) has been created instead. Surgically created choledochoduodenal anastomoses are usually found in the duodenal bulb (D1). As they are often large, cholangiography through these openings may require occluding them first with a balloon catheter, then injecting contrast under pressure (occlusion cholangiography). Duodenal diverticula frequently involve the main papilla, significantly altering the axis of the bile duct, and sometimes complicating cannulation ( Fig. 2 ). I still get referrals from community endoscopists who abandon ERCP as soon as they see the papilla anywhere in the vicinity of a diverticulum; however, in practice, most papillas in and around duodenal diverticula can be cannulated with minor modifications to standard technique. The “danger” of diverticula is their thin wall and the risk of perforation from repeated unsuccessful instrumentation. Adjunctive techniques, especially stenting the PD first ( Fig. 3 ), can significantly increase the safety and success of biliary cannulation and therapy in this setting. Great care must be taken when using a needle knife near or within a diverticulum; however, with a relaxed patient and a steady hand, small, precise incisions can be made safely ( Fig. 4 ). The increasing trend toward monitored anesthesia care and general anesthesia for ERCP has undoubtedly led to more successful procedures. Trying to cannulate a tiny target in an agitated, retching, inadequately sedated patient is a miserable experience for all concerned, and a challenge even for an expert. Leaving aside the current debate about who should be allowed to administer anesthesia for endoscopy, there is no doubt that anesthesia-assisted ERCP is here to stay.

If we look at the “normal” duodenal papilla using the duodenoscope, the axis of the bile duct should be in the 11 o’clock position, while the PD courses “backward” and a little to the right (the 3 o’clock position) ( Fig. 5 ). When attempting to access the bile duct with a cannula, the tip should be used to gently probe the papilla in the expected direction. If an orifice is not visible, there are usually clues to its whereabouts in the fine surface anatomy. With a straight catheter, biliary cannulation requires coming at the papilla from below; with a papillotome one has the advantage of being able to vary the tip angulation by tightening or relaxing the cutting wire. Gentle lifting using the elevator (or “bridge”) and/or pulling the endoscope back a little will often “seat” the catheter in the biliary opening; however, if a papillotome is being used, in a “bowed” configuration, the upward angle of the tip may actually impede deep cannulation by impacting on the “roof” of the duct. The “trick” to advancing the catheter at this point is to reduce the tip angulation by a small amount (relax the cutting wire), which brings it into line with the bile duct axis ( Fig. 6 ). This makes the process sound easy, which it is frequently not.