Pancreatic Sphincterotomy

Preparation

As with all endoscopic procedures, it is imperative to obtain informed consent. This is paramount when discussing with patients and their families the potential risks involved in performing endoscopic retrograde cholangiopancreatography (ERCP) with pancreatic sphincterotomy, as the adverse event rates are higher compared with routine upper endoscopy. Routine blood work, including a complete blood count, and coagulation parameters are verified before the procedure in selected patients (see Chapter 10 ). Antithrombotic agents are withheld, as appropriate. Antibiotics are administered preprocedurally in an effort to prevent procedure-related infection in the presence of pancreatic pseudocysts and other fluid collections and when incomplete pancreatic drainage is anticipated, as is done for biliary procedures. The data supporting antibiotic prophylaxis before pancreatic sphincterotomy are sparse. Only a few studies have attempted to investigate this issue, and most of them have had small numbers with poorly defined endpoints. Coverage with a second-generation or third-generation cephalosporin appears sufficient. Broader-spectrum antibiotics, such as piperacillin/tazobactam—or vancomycin and gentamicin if there is a penicillin allergy—may be warranted in some instances.

Equipment

Pancreatic sphincterotomy, like biliary sphincterotomy, is performed with a standard side-viewing duodenoscope, the appropriate sphincterotome (papillotome), and an electrosurgical generator. There are a variety of options in terms of commercially available electrosurgical generators (see Chapter 11 ). Most have both monopolar and bipolar options, and they offer pure cutting, pure coagulation, and blended (cut/coag) current modes. These generators are the same as those used when performing colonoscopic polypectomies. Newer models even allow for cutting options that incrementally splice the sphincter muscle in 1-mm segments, informing the endoscopist with an audible alarm at the end of each segment. This attempts to ensure that the sphincterotomy is performed in a careful, stepwise fashion without producing an unintentional exaggerated cut. However, there are no data that verify the effectiveness of this method.

There is little evidence supporting the use of one current mode over the others when performing biliary sphincterotomy. Some data, however, suggest that pure cutting current may be associated with less post-ERCP pancreatitis compared with blended current. Also, the use of pure cutting current is thought to cause less fibrosis, thus diminishing the risk of papillary stenosis. As a result, some endoscopists advocate using only the pure cutting mode when performing a pancreatic sphincterotomy. It is unclear whether there is an increased risk of bleeding, as some have suggested.

A wide variety of sphincterotomes and guidewires are commercially available for use in pancreatic sphincterotomy. For a more detailed description of endoscopic guidewires and ERCP accessories, refer to Chapter 4 . The original Demling-Classen or Erlangen pull-type sphincterotome (bowstring design) is still the most popular choice for performing pancreatic sphincterotomy ( Fig. 20.1 ). There are several variations of this type of sphincterotome based on differences in the length of the exposed cutting wire, the number of additional lumens, and differences in the length of the “nose” of the instrument. A shorter nose (5 to 8 mm beyond the wire) is sometimes more convenient for cannulation of the major papilla before sphincterotomy. It allows for easier engagement between the sphincterotome tip and the papilla without much interference from the cutting wire. Once the tip is positioned inside the papillary orifice, tension on the wire may be applied to bow the tip into the correct axis and correctly align the instrument for eventual sphincterotomy. Sphincterotomes with longer noses (2 to 5 cm beyond the wire) lose their ability to bow because most of the cutting wire is retained inside the duodenoscope until deep cannulation is attained. The advantage of this type of sphincterotome is the ability to maintain cannulation while the wire is being withdrawn during sphincterotomy. However, now with triple-lumen cannulas and soft-tip and flexible-tip guidewires that cause less injury to the pancreatic duct, a guidewire can be easily left in place within the pancreatic duct in order to maintain cannulation while performing a pancreatic sphincterotomy (wire-guided sphincterotomy). This technique of wire-guided sphincterotomy is now considered the standard of care for both pancreatic and biliary sphincterotomy.

Standard sphincterotomes have a 5-Fr to 7-Fr catheter tip that can accept a 0.035-inch guidewire. Use of a triple-lumen cannula allows for the placement of a preloaded guidewire and simultaneous contrast injection without having to remove the guidewire. When manipulating the papilla and the most proximal portions of the main pancreatic duct before sphincterotomy, many endoscopists prefer an ultratapered catheter tip (5 Fr–4 Fr–3 Fr) for easier cannulation. These sphincterotomes require the use of smaller-caliber guidewires, frequently down to 0.018-inch diameter. Conversely, a special 3-Fr cannula can be passed through the channel of a standard sphincterotome to produce the effect of a tapered-tip catheter.

Endoscopic pancreatic sphincterotomy is performed after deep cannulation of the main pancreatic duct with a guidewire. There are several different types of commercially available guidewires that may be used to perform this technique. Such configurations of guidewires include conventional, nitinol, hydrophilic, and “hybrid.” The range in wire diameter is from 0.018 to 0.035 inches. When performing a wire-guided pancreatic sphincterotomy, hydrophilic-coated wires with soft and floppy tips may be helpful in preventing trauma to the main pancreatic duct and its side branches. As mentioned above, this deep wire-guided technique in pancreatic sphincterotomy has obviated the need for longer-nose sphincterotomes. Maintaining adequate cannulation of the papilla in this manner is less traumatic and more secure.

The Endoscopic Technique

The main principles involved in pancreatic sphincterotomy are similar to biliary sphincterotomy (see Chapter 17 ). They involve wire-guided cannulation of the duct before cutting and use a slow and stepwise approach that relies on accurate identification of anatomic landmarks. There are essentially two different types of techniques that are used by most expert endoscopists when performing pancreatic sphincterotomy. The first approach, as well as the more popular one, uses a standard pull-type sphincterotome. The second approach uses an endoscopic needle knife to cut the sphincter muscle after placement of a pancreatic duct stent. Both techniques have their advantages and disadvantages, and the details surrounding each approach are discussed below. In addition, we will briefly describe the technique of precut or “access” pancreatic sphincterotomy in those instances when the endoscopist is faced with a difficult pancreatic cannulation. Sphincterotomy of the minor papilla is discussed separately in Chapter 21 .

As with both biliary and pancreatic sphincterotomy, success starts with accurate cannulation of the correct duct (see Chapter 14 ). This is, at times, the greatest hurdle for novice therapeutic endoscopists. In general, selective cannulation of the pancreatic duct is easier than that of the biliary duct, assuming that there has not been a previous biliary sphincterotomy. The reason for this is directly related to the anatomic axis of each duct in relation to the wall of the duodenum. Although the main pancreatic duct may be tortuous with multiple side branches, the most proximal portion of the duct courses away from the papilla at a 90-degree angle from the duodenal wall ( Fig. 20.2 ). It then runs more toward the right and straight inside. The most distal part of the common bile duct, on the other hand, assumes more of an acute angle in its relationship with the duodenal wall. It extends in an upward and leftward direction from the papillary orifice. This provides for a more difficult cannulation, depending on how acute the angle of takeoff is from the papilla.

One must remember that a cross-sectional view of the inner portion of the ampulla of Vater (the part furthest from the duodenal lumen) is similar to a “double-eyed onion,” with each duct running off in its own unique direction. The most proximal portion of the ampulla, however, is a single orifice that leads from the lumen of the duodenum into a common channel. This common channel then merges with the “double-eyed onion.” The length of this channel is variable but usually ranges between 1 and 10 mm. Within this channel are several folds of papillary mucosa that may often act as obstacles to selective cannulation with the sphincterotome. Therefore accurate cannulation depends on finding the correct axis with the catheter tip before the guidewire can be pushed all the way out into the main pancreatic duct. Approaching the papillary orifice with the right orientation allows the endoscopist to find the correct axis.

When aiming for the pancreatic duct, the catheter should enter the orifice perpendicular to the duodenal wall. Then, to traverse the correct plane, the catheter tip should be advanced along the floor of the orifice to find the pancreatic duct. This is in contrast to biliary cannulation, in which the catheter tip is aimed at the roof of the papillary orifice to find the distal common bile duct. The only way to ultimately assure correct cannulation is to (1) gently advance the guidewire into the duct and confirm fluoroscopically the position of the wire in a transverse direction toward and/or across the spine or (2) inject contrast to verify one's position within the duct fluoroscopically. To limit the risk of pancreatitis, as little contrast as possible should be used in this situation.

The importance of correct ductal axis is paramount. When faced with difficult pancreatic duct cannulation, one may have to lower the catheter tip even further when advancing along the floor of the papillary orifice. This can be achieved by lowering the elevator on the duodenoscope, thus pressing down on the floor. The injection of contrast is done simultaneously in an effort to correctly identify the pancreatic duct.

Pull-Type Sphincterotomy

After successful pancreatic cannulation and advancement of the guidewire into the main pancreatic duct, confirmation of position is usually obtained with a contrast pancreatogram. Assuming that a clear indication for sphincterotomy has been established, this part of the procedure is most often performed with a pull-type sphincterotome (as mentioned above). As with biliary sphincterotomy, the incision should be “hot and slow.” It should be directed toward the 1 to 2 o'clock position with the very distal part of the cutting wire. In other words, most of the cutting wire should be visible outside the papillary orifice. Note that the direction of the cut is very different from that of a biliary sphincterotomy ( Fig. 20.3 ). When performing biliary sphincterotomy, the cutting direction is in the 11 to 1 o'clock position (preferably the 12 o'clock position). The sphincterotome is slightly bowed while the cutting wire is “walked up” the roof of the papilla in a stepwise fashion. In pancreatic sphincterotomy the same principles apply, but the direction is more toward the right, guiding the cutting wire along the floor of the papillary orifice.

The actual incision should be performed using the pure cutting current with the electrosurgical generator. This prevents further damage to the pancreas and limits the risk of fibrosis and papillary stenosis. The length of the cut is generally between 5 and 10 mm. Larger-diameter ducts require longer cuts in order to achieve the largest possible access. Once the sphincterotomy has been completed, a temporary pancreatic stent is usually left in place for a short period in order to facilitate adequate drainage from the duct (assuming that larger stents are not placed for treatment of strictures, leaks, etc.). The edema that ensues after pancreatic sphincterotomy can cause ductal obstruction and acute pancreatitis. Placement of a pancreatic stent after every pancreatic sphincterotomy is nearly universal. However, the stent type chosen and the desired duration of dwell time have been debated.

Early in the era of pancreatic sphincterotomy, many endoscopists advocated always performing this procedure in concert with a prior biliary sphincterotomy. Biliary sphincterotomy done immediately before pancreatic sphincterotomy is felt by some to allow for easier identification of clear anatomic landmarks, thus making it safer and more effective. It may provide better exposure of the pancreaticobiliary septum and therefore allow improved access to the desired pancreatic tissue. Also, this approach prevents the rare possibility of biliary adverse events after a primary pancreatic cut. The adverse events include inadvertent damage to the distal bile duct and possible biliary obstruction because of edema adjacent to the biliary duct orifice. Many expert endoscopists recommend a biliary sphincterotomy before a pancreatic sphincterotomy in cases of cholangitis or obstructive jaundice, presence of a common bile duct diameter >12 mm, or an alkaline phosphatase level greater than twice normal. It may also be done when it is needed to obtain better access to the main pancreatic duct.

When performing a pancreatic sphincterotomy after a biliary sphincterotomy, the anatomic landmarks are different. Part of the papilla has already been filleted open for this procedure, and so the pancreatic orifice is usually seen at the 5 o'clock position near the right margin of the sphincterotomy. Transient opening of the pancreatic duct will allow for better visualization and more accurate cutting. This may be achieved by gently sucking air into the duodenum with the scope. Once the orifice is correctly identified and cannulated, the sphincterotomy can be carried out in a similar fashion as described above ( Box 20.1 ).

Box 20.1

The Pull-Type Sphincterotome Technique

• Direction of the incision is along the 1–2 o'clock position.

• Pure cutting current should be used.

• Incision should be “slow and hot.”

• Majority of the cutting wire should be outside the papillary orifice.

• Length of the incision is generally between 5 and 10 mm.

• A pancreatic duct stent is inserted after completion.

• May or may not be preceded by a biliary sphincterotomy.

Needle-Knife Sphincterotomy

An alternative method to pancreatic sphincterotomy uses an endoscopic needle knife instead of a standard pull-type sphincterotome (see Fig. 20.1 ). Cutting with the needle knife is done after placement of a pancreatic duct stent. The tip of the needle knife is placed at the most proximal portion of pancreatic sphincter tissue that is overlying the stent. The stent is used as a guide to direct the cut along the plane of the pancreatic duct, and the needle knife tip is advanced over the top of the stent and down its longitudinal axis ( Fig. 20.4 ). Incision length is similar to that of sphincterotomy with a pull-type sphincterotome; that is, the length is generally between 5 and 10 mm. Many experts believe that a prior biliary sphincterotomy is especially helpful before using this needle-knife technique. Good exposure of the pancreaticobiliary septum allows for better tissue access and more effective “septotomy.”

There are a few limitations to this technique, however. The absolute prerequisite of pancreatic duct stent placement makes it a technique that may not be feasible if a stent cannot be placed. For example, in chronic pancreatitis it may be very difficult to insert a stent without first removing ductal calculi. Furthermore, using the pull-type sphincterotome technique allows a more thorough assessment of sphincterotomy completeness. The endoscopist can reassess the incision and extend the cut, if necessary, with the sphincterotome wire. This is not possible with the needle-knife and stent technique. Lastly, many endoscopists find it simpler and faster to perform the sphincterotomy without having to first place a pancreatic stent ( Box 20.2 ).

Box 20.2

The Needle-Knife Technique

• A pancreatic duct stent is always inserted beforehand.

• The needle knife is advanced over the top of the stent.

• Pure cutting current should be used.

• Length of incision is between 5 and 10 mm.

• Frequently preceded by a biliary sphincterotomy.

Despite the fact that pancreatic sphincterotomy is performed by only two different techniques, survey questionnaires show a lack of expert consensus in terms of the best approach. A previous survey of 14 expert endoscopists in 9 US centers showed that 6 of those 14 gastroenterologists either “always” or “often” used the pull-type sphincterotome technique, whereas 7 of them “always” or “often” used the needle-knife technique. Eight physicians “always” performed a biliary sphincterotomy before pancreatic sphincterotomy, and only 2 of the 14 used pure cutting current during the procedure ( Table 20.1 ). Almost all endoscopists insert a pancreatic stent after sphincterotomy, as it lowers the likelihood of post-ERCP pancreatitis. However, the type of stent used and dwell time are quite variable among those who perform pancreatic sphincterotomy regularly. Questions surrounding these differences among techniques can be answered only with future randomized trials that examine both the short-term and long-term outcomes of each ( Box 20.3 ).

TABLE 20.1

Differences in Technique of Pancreatic Sphincterotomy Based on a Survey of 14 Expert Endoscopists

Modified from Alsolaiman M, Cotton P, Hawes R, et al. Techniques of pancreatic sphincterotomy: lack of expert consensus. Gastrointest Endosc. 2004;59:AB210. With permission.

	Always	Often	Sometimes	Never
PTS	3	3	7	1
NK	1	6	5	2
EBS	8	4	1	1
PC	2
BC	12
PS	12	2

BC, Blended current; EBS, endoscopic biliary sphincterotomy before pancreatic sphincterotomy; NK, needle-knife technique; PC, pure cutting current; PS, pancreatic stent placement afterward; PTS, pull-type sphincterotome.

Box 20.3

Controversies Surrounding Pancreatic Sphincterotomy

• Pull-type sphincterotome technique versus needle-knife technique

• Biliary sphincterotomy before pancreatic sphincterotomy?

• Blended current versus pure cutting current

• Pancreatic stent versus no stent after sphincterotomy

• If stent, what type of stent? How long should the stent stay in place?