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Difficult Cannulation and Sphincterotomy
Introduction
Endoscopic retrograde cholangiopancreatography (ERCP) requires several years of dedicated training and continuous refinement of knowledge and skill. Selective ductal cannulation is the sine qua non for diagnostic and therapeutic ERCP. General issues on cannulation have already been highlighted in Chapter 40 . In a 2017 consensus report, difficult papillary access is defined as the inability to achieve selective biliary cannulation by standard ERCP techniques within 10 minutes or up to five cannulation attempts. This chapter concentrates on variations of standard techniques to overcome challenges to standard cannulation, including in patients with anatomic variations, gastric outlet obstruction, and surgically altered anatomy. With the development of endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP), ERCP has moved from a diagnostic to an almost purely therapeutic procedure. When used as a diagnostic procedure, image-guided tissue sampling with forceps biopsy, brush cytology, or cholangiography are performed. For this reason sphincterotomy is necessary for most cases of diagnostic or therapeutic ERCP.
Standard Accessories
Standard Cannulas
Cannulation catheters range in size from 5 Fr (French) to 7 Fr. They are usually made of Teflon. The tip can be straight, tapered, or rounded, and accepts up to a 0.035-inch guidewire. Tapered tip catheters probably confer a higher risk of submucosal injection.
Sphincterotomes
Sphincterotome catheters are modified with an electrosurgical cutting wire at their distal end. Like cannulation catheters, they are usually made of Teflon. The cutting wire can be placed under tension to “bow” the tip of the catheter, providing another articulation to facilitate cannulation. The tensed wire is also used to perform sphincterotomy.
To facilitate cannulation, double- or triple-lumen sphincterotomes are available. They allow the introduction of a wire to accomplish a therapeutic task, and in the case of a triple-lumen sphincterotome, allow injection of contrast with a guidewire in place. Due to the small size of the injection channel, contrast flow is slow, and the use of a small syringe is recommended to facilitate injection.
In general, sphincterotomes require a higher level of coordination between the endoscopist and the assistant controlling flexure of the device. Short-wire systems, in which the guidewire can be stripped external to the catheter, allow the endoscopist to control and lock the guidewire, reducing the need for coordination between the assistant and endoscopist.
Catheter Versus Sphincterotome for Cannulation
A standard 6-Fr catheter with a 4-Fr tip accepting a 0.035-inch guidewire was the traditional first choice for cannulation. The advantage is high flexibility compared with a 6-Fr sphincterotome. The cannulation catheter could be used directly for deep cannulation (e.g., 0.035-inch J-tip with a hydrophilic Terumo guidewire [Terumo Medical Corporation, Tokyo, Japan]). For further intervention, the guidewire could be kept in place.
Sphincterotomes have largely supplanted the standard catheter in many institutions because they permit bowing of the catheter tip to facilitate alignment with the intraduodenal segment of the bile duct and because sphincterotomy is anticipated in the vast majority of ERCP procedures performed.
Data suggest an advantage of sphincterotome cannulation over standard catheter cannulation (84%–97% vs. 62%–75%), but there is a great deal of heterogeneity in available studies, with variable criteria used to define cannulation failure.
Guidewires
Guidewires are frequently used for attaining and maintaining access to the biliopancreatic ducts. Several studies have reported that wire-guided cannulation techniques increase cannulation success and may lower post-ERCP pancreatitis rates.
The configuration of the guidewire tip can be straight or angled (J-shaped). Stiff shaft guidewires (e.g., monofilament guidewires) minimize lateral divergence and facilitate forward transmission of forces. To obtain access through biliary strictures, guidewires with activated hydrophilic coatings and flexible leading tips are generally recommended. For angulated accesses, the J-shaped distal end of a hydrophilic guidewire (e.g., Terumo 0.035-inch) can be customized by means of an anatomical forceps ( and Fig. 50.1 ). Guidewire tip steering is facilitated by a self-fixing torque aid (Terumo Corp.) ( Fig. 50.2 and ).
Currently available guidewire types include conventional, hydrophilic, and “hybrid,” ranging from 0.018 to 0.035 inches in diameter and 260 to 480 cm in length. Enteroscopy length wires are available for balloon-assisted ERCP. Wire lengths greater than 400 cm are used for exchange of devices that are not compatible with the short-wire system. Only insulated (coated) wires should be used during electro-cautery applications to prevent aberrant transmission of electrosurgical energy. Coated wires have a monofilament core of nitinol or stainless steel and an outer sheath of lubricious material (Teflon, polyurethane). Depending on the outer sheath, it is possible to improve radiopacity, slipperiness, and electrical insulation properties. To improve guidewire manipulation and accessory exchange, catheter lumens should be flushed with water to reduce friction with the guidewire.
Difficulties in Cannulation of the Papilla
One should develop and employ a pragmatic step-up approach to cannulation. Each escalating technique may be tried several times before moving up to the next method until success is achieved. One traditionally preferred progression begins with a sphincterotome flushed with contrast. The ampulla is inspected for its anatomic features in an attempt to localize the desired duct orifice and to determine the optimal angle of ductal traverse of the ampulla. For biliary cannulation, the catheter tip should be directed toward the 11 o'clock orientation with the catheter tip bowed to parallel duct alignment ( Fig. 50.3 ). The surface of the ampulla should be gently stoked downward to the selected entry point (intended to deflect the fimbria separating the pancreatic and biliary orifices in the common channel) and the catheter tip advanced into the papillary meatus with an outward and upward deflection of the catheter. Gentle injection of contrast under fluoroscopic guidance will inform the catheter position as in the bile duct, pancreatic duct, common channel, or none of these. If the bile duct fills, further contrast should be injected and the catheter slid deeply into the common bile duct or, in the case of a triple-lumen catheter, the guidewire advanced. When the bile duct does not fill, bow the sphincterotome tip upward and tent the ampulla toward the endoscope and inject again. If still no filling, we employ a technique in which the sphincterotome is bowed and impacted into the papillary meatus at the 11 o'clock orientation, then the endoscopist deflects the endoscope toward and above the ampulla while slightly withdrawing the catheter within the accessory channel (so as to sustain a static depth of catheter tip entry into the papilla). This is performed concurrent with the assistant decreasing the tension on the bow of the sphincterotome. This maneuver helps direct the catheter into the location and orientation of the bile duct.
For selected pancreatic duct cannulation, the 5 o'clock papillary orientation is targeted, and with a straighter, as opposed to bowed, address ( Fig. 50.4 ).
The guidewire cannulation technique is favored by many endoscopists. Herein, a straight or angled-tip guidewire is advanced to the tip of the catheter (standard or sphincterotome). The catheter tip is inserted into the desired location and angulation within the meatus, and the guidewire gently advanced under combined endoscopic and fluoroscopic guidance. Levels of resistance are appreciated, and we commonly “jiggle” the wire tip to seek out the desired ductal entry. Another approach is to advance the catheter into the papillary orifice with the guidewire tip extending slightly from the tip of the catheter. Lastly, the catheter can be set to hover just before the papilla and the guidewire advanced into the desired location within the papilla.
When there is repeated injection or guidewire advancement into the pancreatic duct, two techniques may be used to isolate it and facilitate selected bile duct cannulation. The first is to advance the guidewire into the pancreatic duct, exchange out the catheter, load it with another wire, and reinsert it alongside the pancreatic guidewire to attempt cannulation just above and to the left of the guidewire insertion point. This is known as the double guidewire technique. The second approach is to place a 3- to 5-Fr pancreatic duct stent and similarly cannulate just above and to the left. Both these approaches may be used to facilitate access prior to needle-knife sphincterotomy, detailed later.
Access Sphincterotomy in Difficult Papillary Cannulation
Standard cannulation techniques may fail even in the most experienced endoscopist's hands. A difficult anatomical position with inability to align the axis of the catheter and guidewire with the axis of bile or pancreatic duct may lead to failure of papillary cannulation. Other reasons may include impacted calculi, papillary stenosis, ampullary neoplasm, or duodenal inflammation.
Access sphincterotomy (sometimes referred to as pre-cut sphincterotomy) commonly facilitates biliary cannulation safely and effectively in the hands of the experienced endoscopist. However, potentially severe complications may occur when performed by those who are inadequately trained. The needle knife is the most common tool for access sphincterotomy ( Fig. 50.5 ). Success rates vary widely according to the frequency of use and experience of the individual endoscopist, and range from 68.4% to 92.5%.
There are two predominant access sphincterotomy techniques. For the conventional access sphincterotomy, the needle-knife tip is engaged within the papillary orifice and aligned with the presumed axis of the bile duct and papillary roof. Care has to be taken to modulate the cutting depth. Some advise beginning with a superficial cut of the papillary roof, starting at the papillary orifice, transecting first the mucosa and incrementally cutting until the muscle layer of the common sphincter is visualized. The round or point-like aspect of the biliary orifice may be seen and then selectively cannulated with a hydrophilic guidewire exiting 2 mm from a cannula or sphincterotome. Even if 11 o'clock is a common position of the biliary sphincter, this may vary, and careful identification of the round structure of the biliary orifice and distal biliary sphincter muscle is the most important pathfinder. In the case of failed pancreatic cannulation, a biliary sphincterotomy, using standard or needle-knife technique, may be performed to better expose the pancreatic orifice, which is typically found in the 5 o'clock position. After selective deep duct cannulation, a guidewire sphincterotomy is often performed to also open the biliary or pancreatic sphincter and to achieve an optimal permanent access and drainage.
The alternative techniques for access sphincterotomy are starting suprapapillary and cutting downward toward the papilla face, or direct puncture fistulotomy into the roof of the papilla.
Access sphincterotomy is used in 3.8% to 19.2% of ERCP procedures, with a success rate ranging from 75% to 99% and complication rates from 1.9% to 30%. Complications of precut sphincterotomy are similar to those with conventional sphincterotomy, such as bleeding, perforation, pancreatitis, and cholangitis. The complication rates reported in international studies are in the range of 7% to 13.3%. Risk factors for complications include young age, an inexperienced operator, periampullary carcinoma, diverticulum, sphincter of Oddi dysfunction, and nondilated common bile duct.
The timing of and decision to perform access sphincterotomy should be individualized based on the indication for the procedure, the ampullary characteristics, and the endoscopist's training and experience, with a continuous weighing of the potential procedural expectations, risks, and benefits, including the risks associated with failed cannulation.
Periampullary Duodenal Diverticula
Duodenal diverticula are found in up to 15% of patients undergoing ERCP. They are defined as herniation of the mucosa or submucosa that occurs via a defect in the muscle layer. Some papillae are located on the edge of diverticula, others partially or completely within the diverticulum. Any of these locations may make access to the papilla for cannulation difficult or impossible. Due to the distortion, the pancreatic and biliary orifice locations can even be reversed. Depending on the position of the papilla and the distortion level, cannulation can be straightforward or extremely difficult. Thus, the challenge is to approach in the appropriate axis for access.
Success rates for cannulation in the context of periampullary diverticula versus no diverticulum are 62.4% versus 92.7%, respectively. In contrast, Panteris et al (2008) reported similar success rates with or without diverticula, after excluding cases with undetectable papillae (94.9% vs. 94.8 %).
The most common problem in patients with periampullary diverticula is the inability of the endoscopist to detect the orifice of the papilla. In a review article by Altonbary et al (2016), the following tips are presented:
- 1.
In most cases, the papilla is located on the lower edge of the diverticulum or just inside, somewhere between the positions of 3 o'clock and 8 o'clock.
- 2.
Very large diverticula are usually divided by a ridge-like septum. This ridge typically overlies the bile duct and terminates inferiorly at the papilla.
- 3.
A catheter can be used to straighten and evert the folds to identify a hidden papilla within the diverticulum.
- 4.
Advancement of the tip of the duodenoscope into the sac is also possible, but care must be taken to avoid perforation.
- 5.
Due to the altered anatomy, the biliary duct is often not acutely angulated superiorly, but runs more directly. Thus, acute angulation of the sphincterotome is not necessary.
- 6.
In some cases, air aspiration shows the side of the diverticulum.
- 7.
Changing patients' position to the abdominal (prone) position or pushing the upper right abdominal quadrant of the patient can help.
- 8.
Instillation of saline solution on the contralateral side of the diverticulum may cause the papilla to protrude.
Special Cannulation Techniques in Periampullary Duodenal Diverticula
Numerous techniques have been described to overcome difficulties in cannulation of an intra-diverticular papilla. Their use should be individualized based on specific indications and circumstances.
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