Precutting

Precutting is a useful technique to achieve selective bile duct cannulation when free or wire-guided approaches fail. The objective of precutting is to incise the roof of the papilla to expose the underlying opening of the bile and pancreatic ducts for selective cannulation. The widely used term precut papillotomy is misleading, because the term papillotomy has been used interchangeably with the term sphincterotomy. The term papillary roof incision more accurately describes the procedure of precutting.

Precutting is performed with either a needle-knife catheter (Fig. 27.3, top) or Erlangen-type precut papillotome (Fig. 27.3, bottom). Most of the published experience has been with the needle-knife catheter, which consists of a retractable bare diathermy wire that extends 5 mm from the tip of the catheter; the needle is inserted at or just above the papillary orifice, and the cut is directed upward in the 11 to 12 o’clock position (Fig. 27.4). Biliary cannulation success rates exceeding 90% have been reported (Misra, 2009). The needle knife can also be used to create a supraampullary fistula in patients with biliary obstruction as a result of an ampullary malignancy. Another application is to free an impacted stone at the papilla; an incision is made directly into the most bulging portion of the papilla against the surface of the impacted stone. Higher complication rates with precut sphincterotomy for stone extraction have been reported (Pereira-Lima et al, 2001).

FIGURE 27.3 Needle-knife catheter.

FIGURE 27.4 Precutting technique using a needle-knife catheter. A, Insertion of the tip of the precut catheter in the papillary orifice followed by cephalad incision of the papillary roof at the 12 o’clock position with pure-cut current. B, The incised roof retracts, exposing the underlying biliary duct orifice. The bile duct is selectively cannulated.

Precutting is not without risk, but some series suggest that in expert hands, it does not increase the risks of pancreatitis (Lawrence et al, 2009). Two large multicenter studies identified precutting as a significant risk factor for postsphincterotomy pancreatitis, and there have been isolated reports of perforation. Practice guidelines have established that precutting requires appropriate training and expertise and should be reserved for patients with a strong indication for sphincterotomy (Carr-Locke, 2004).

Rendezvous Procedure

Biliary cannulation can be aided by a combined percutaneous and endoscopic approach, known as a rendezvous procedure. A guidewire is inserted via the percutaneous transhepatic route into the duodenum and is subsequently grasped at the endoscopic end. The guidewire is pulled through the working channel of the endoscope and serves as a guide rail to enable retrograde biliary cannulation, sphincterotomy, and further endoscopic intervention (Calvo et al, 2001).

A rendezvous approach also can be used to accomplish biliary or pancreatic duct cannulation under endoscopic ultrasound guidance (Mallery et al, 2004). The bile or pancreatic duct is punctured transduodenally or transgastrically with a standard fine aspiration needle loaded with a guidewire. The wire is advanced anterogradely across the stricture into the duodenum (Fig. 27.5), and the stent is placed over the wire in the standard retrograde fashion.

FIGURE 27.5 Radiographs showing transgastric endosonography-guided puncture and injection of the pancreatic duct (A) followed by anterograde passage of a wire across the stricture into the duodenum (B).

A further variation of the rendezvous approach can be used to achieve cannulation of the pancreatic duct (Bataille & Deprez, 2002). The minor papilla is used to pass a wire from the duct of Santorini into the duct of Wirsung and then across the major papilla. When cannulation of the major papilla is achieved, the wire is rerouted from the minor papilla to the main pancreatic duct (Fig. 27.6).

FIGURE 27.6 Endoscopic image showing a pancreatic rendezvous procedure using the minor papilla to pass a wire anterogradely across the major papilla into the duodenum.

Juxtapapillary Diverticula

Frequently found in elderly patients, juxtapapillary duodenal diverticula alter the position and anatomic boundaries of the papilla and displace the course of the bile and pancreatic ducts, making cannulation more difficult (Panteris et al, 2008). Accessing the papilla is a problem when it is located within the diverticulum, but various ancillary maneuvers may improve access. Aspirating air from the diverticulum may help “evert” the diverticulum, bringing the papilla into a more favorable position for cannulation. Altering the patient’s position and applying abdominal pressure may also be helpful. Failing these, a small depot of normal saline can be injected into the submucosal plane of the mucosa adjacent to the papilla. The injection should be made on the diverticular side of the papilla in an attempt to “tilt” it toward the endoscopist (Fig. 27.7). The use of two accessories, forceps and cannula, inserted together through the working channel to enable the endoscopist to pull the papilla out of the diverticulum and cannulate the papilla simultaneously also has been described (Fujita et al, 1998).

FIGURE 27.7 Technique to improve access to a papilla located on the inner surface of a diverticulum. A, With a standard injection catheter, 1 to 2 mL of saline is injected adjacent to the papilla on the diverticular side. B, Raised submucosal tissue “tilts” the papilla into view.

Deep cannulation of the bile duct adjacent to a large juxtapapillary diverticulum may be difficult, because the diverticulum distorts the course of the distal common bile duct. It is helpful to alter the direction of cannulation after entering the biliary orifice according to the anatomy of the diverticulum (Fig. 27.8). The direction of cannulation may be caudal rather than cranial; a guidewire tends to straighten the course of bile and pancreatic ducts and may facilitate deep cannulation (Draganov et al, 2005).

FIGURE 27.8 Technique for deep cannulation of the bile duct in the setting of a large juxtapapillary diverticulum. A, Slight withdrawal of the endoscope shifts the angle of cannulation more caudad. B, The catheter is advanced while gradually straightening the cannulation angle.

Billroth II Gastrectomy

A patient who has undergone a Billroth II gastrectomy poses a special challenge to the endoscopist. Accessing the papilla is the first obstacle. When the afferent loop is long, it can be difficult to intubate, and the papilla can be difficult to reach. Cannulation of the Billroth II papilla is the second obstacle. Because the endoscope approaches the papilla from below rather than above, the papillary anatomy in a Billroth II patient appears reversed. The bile duct is cannulated by orienting the catheter downward, toward the 5 to 6 o’clock position, rather than toward the standard 11 to 12 o’clock position. It is helpful to use a new, straight catheter or mold a downward bow into the catheter to achieve this (Fig. 27.9). A rotatable sphincterotome can also aid in the cannulation of the bile duct (Kim et al, 2008). Cannulation of the pancreatic duct is achieved by inserting the catheter at the 11 o’clock position and aiming it upward in a right-to-left orientation. The bile duct is usually easier to cannulate than the pancreatic duct, because the catheter is automatically directed in the axis of the bile duct. The placement of a guidewire into the bile duct aids in the placement and performance of the sphincterotomy (Dolay & Soylu, 2008).

FIGURE 27.9 Cannulation of the bile duct with reversed anatomy after Billroth II gastrectomy.

Mechanical Lithotripsy

Using mechanical lithotripsy, the stone is forcefully crushed in the arms of a Dormia basket after entrapment. This method is the simplest and most cost-effective of the lithotripsy techniques, with success rates of 80% to 90%. There are two variations to the technique of mechanical lithotripsy: a nonendoscopic method and a through-the-endoscope method. Using the nonendoscopic method, the stone is captured within a standard Dormia basket, the basket handle is cut off, and the endoscope is removed. A coiled metal sheath is inserted over the wire, until its tip is in contact with the stone, and mechanical lithotripsy is performed (Fig. 27.17). Using the through-the-endoscope method, a special lithotripsy basket contained within a metal sheath is inserted through the endoscope working channel (Fig. 27.18). The stone is captured in the basket, and lithotripsy is performed. Because the basket is part of a single-unit lithotriptor device, this method presumes that the endoscopist anticipates the need for mechanical lithotripsy before an attempt is made to extract the stone. If stone extraction is attempted with a standard Dormia basket, and the stone and basket become impacted in the bile duct, the endoscopist must use the nonendoscopic method to effect fragmentation.

FIGURE 27.17 Radiographs showing intraductal mechanical lithotripsy of a large stone using the nonendoscopic approach. A, Impacted stone captured in standard Dormia basket. B, Endoscope removed. C, Lithotripsy cable sheath advanced to the stone for mechanical lithotripsy.

FIGURE 27.18 Radiographs showing through-the-endoscope lithotripsy. A, Impacted stone captured in the lithotriopsy basket. B, Lithotriopsy cable advanced through the endoscope to perform lithotriopsy.

Intraductal Shock-Wave Lithotripsy

Failure of mechanical lithotripsy is usually due to an inability to capture the stone in the basket, which may occur if the stone is firmly impacted or very large. An alternative modality to achieve stone fragmentation is to use shock waves, which can be delivered intraductally or extracorporeally. Intraductal lithotripsy is performed using flexible probes that can be introduced into the bile or pancreatic duct. The shock waves are generated using electrohydraulic or laser technology and are applied directly to the stone surface. Because shock waves can cause injury to the duct wall, intraductal lithotripsy generally is performed under endoscopic guidance using a “baby scope” inserted into the duct via the duodenoscope, or “mother scope” (Fig. 27.19; Swahn et al, 2009). The lithotripsy probe is inserted through the operating channel of the baby scope, and shock waves are fired under visual guidance, until adequate stone fragmentation is achieved (Fig. 27.20). In patients with an altered anatomy, a nonoperative approach can be taken, using a holmium laser delivered through a choledochotomy (Bark et al, 2009).

FIGURE 27.19 “Baby scope” (arrow) inserted through the working channel of the “mother scope” (duodenoscope).

FIGURE 27.20 Intraductal shock-wave lithotripsy. A, The video cholangioscope has been inserted into the bile duct to visualize the stone. B, Radiographic view showing lithotripsy under direct cholangioscopic vision.

Extracorporeal Shock-Wave Lithotripsy

Extracorporeal shock-wave lithotripsy (ESWL) has been shown to be an effective and safe method to fragment bile and pancreatic duct stones that defy endoscopic extraction. The technique can be used for fragmentation of bile duct stones using fluoroscopic or ultrasound guidance (Amplatz et al, 2007). However, if the stone is not visible by fluoroscopy or ultrasound, ESWL is not possible (Merrett & Desmond, 1990). After fragmentation of any stones, the residual fragments must be removed, usually aided by endoscopic sphincterotomy (Tandan et al, 2009). The need for ESWL has decreased as the effectiveness of mechanical lithotripsy has improved. Pancreatic stone fragmentation with ESWL requires multiple sessions and endoscopic management that includes pancreatic sphincterotomy and stent placement (Brand et al, 2000).

Chemical Dissolution

Monooctanoin and methyl tert-butyl ether (MTBE) have been used to dissolve common bile duct stones via nasobiliary drainage catheters and T-tubes (Tandon et al, 1990). Despite encouraging initial reports, this approach has been abandoned because of the cumbersome and time-consuming technique, poor overall results, and adverse effects related to leakage of the solvent into the duodenum. The administration of ursodeoxycholic acid in combination with endoscopic stent placement was shown in one study to soften and decrease the size of common bile stones, facilitating endoscopic extraction (Han et al, 2009). This approach is taken when initial stone extraction and fragmentation is unsuccessful.

Types of Stents

Two types of stents are used, made of either plastic and expandable metal (Fig. 27.23). Plastic stents may be straight, with flaps for anchorage, or they may be a single or double pigtail (Jain et al, 2000). Expandable metal stents may be uncovered or covered. The covering of the expandable stent may block drainage of a neighboring duct, so covered stents should be restricted to distal bile duct strictures and must be used cautiously in patients with a gallbladder. Covered stents may extend patency rates by preventing tumor or hyperplastic tissue ingrowth, but this requires further study. Plastic stent migration out of the stricture is more commonly seen in benign strictures requiring the use of longer stents (Arhan et al, 2009), and the frequency of stent occlusion is related to the diameter of the metal stent (Loew et al, 2009). Recently, the use and removal of covered metal stents in benign disease has been demonstrated but is associated with a complication rate of 14%. Special “pancreatic” stents made of soft plastic with multiple side holes for drainage of side branches are used in the pancreatic duct. Pancreatic duct stents with large side holes remain patent for longer periods than stents with small side holes (Buscaglia et al, 2009); however, most pancreatic stents are placed for short-term prophylaxis to maintain sphincter patency (Chahal et al, 2009). Long-term use of fully covered metal stents in pancreatic duct strictures has been reported, but the migration rates are high (Park et al, 2008).

FIGURE 27.23 Straight plastic (A) and expandable metal (B) stents.

Technique of Stent Placement

After diagnosing the type and site of the obstruction with a diagnostic ERCP, a small sphincterotomy is often performed to facilitate insertion of instruments. The stricture is negotiated with a guidewire; use of short guidewires may decrease the duration of the procedure and time spent on wire exchanges (Reddy & Draganov, 2009). The technical success of stent placement has been enhanced by the use of hydrophilic wires, which allow easier and less traumatic passage through strictures. In addition, various maneuvers may facilitate the negotiation of a tight stricture: The angle of access to the stricture can be changed by adjusting the position of the guide catheter tip, and an angulated guidewire tip may be helpful for negotiating eccentric strictures. For concentric strictures, an inflated balloon catheter inserted over the guidewire centers the guidewire in the lumen. When the stricture is passed with a wire, a dilating catheter is coaxially inserted to dilate the stricture and obtain a complete cholangiogram. Cytology brushings can be obtained at this point to confirm malignant obstruction. A stent (plastic or expandable metal) is inserted using the Seldinger technique. Decompression of the obstructed biliary tree is typically indicated by a gush of dark stagnant bile into the duodenum.

Hilar Strictures

Hilar strictures are often difficult to stent, because they are further away from the endoscope and tend to be tortuous and sclerotic (see Chapters 28 and 50D). For obstructing hilar cholangiocarcinoma (Klatskin tumors), the success rate of transpapillary stenting varies according to the level of obstruction. For type I strictures (involvement of the common hepatic duct), the success rate is around 86%, but it decreases to 45% for type II strictures (involvement of both main hepatic ducts) and 15% for type III strictures (involvement of secondary intrahepatic branches). Controversy exists as to whether both lobes of the liver need to be drained when a bifurcation lesion obstructs both lobes. Although some studies suggest that unilateral stenting is associated with a high frequency of jaundice resolution, two subsequent studies showed bilateral drainage to be associated with a significantly lower complication rate (Naitoh et al, 2009). Both lobes should be drained in type II and III obstruction if contrast medium fills both hepatic ductal systems and fails to drain. Endoscopic transpapillary stenting may need to be complemented by percutaneous transhepatic stenting when drainage is not complete and jaundice fails to resolve adequately (see Chapters 28 and 50D; Paik et al, 2009).

Dual-stent or multiple-stent insertion for hilar strictures requires a clear outline of the ductal anatomy on cholangiography. The anatomy is best appreciated with the patient in the supine position, because the right and left ductal branches are separated. A wire is advanced into each duct for which stent drainage is planned. A super-stiff 0.038-inch Amplatz guidewire (Boston Scientific, Natick, MA) assists stenting of a tight, angulated stricture. After wire placement, the strictures are dilated with a balloon to facilitate subsequent stent insertion; a 6 mm balloon is generally used. If a balloon catheter cannot be negotiated across a tight stricture, a 7-Fr Soehendra Stent Retriever can be used to core a path through the stricture (van Someren et al, 1996). The left hepatic duct should be stented first, because the left duct has a more acute angle of takeoff from the common hepatic duct (Fig. 27.24).

FIGURE 27.24 Radiographs showing type III malignant hilar obstruction with upstream dilation of the right and left hepatic ducts (A), placement of a left-sided biliary metal stent to drain the left hepatic lobe (B), and placement of a second right-sided biliary metal stent to drain the right hepatic lobe (C).

For malignant hilar strictures, self-expandable metal stents have numerous advantages over plastic stents. Drainage is superior because of the larger diameter and open mesh design that provides drainage of side branches. A sphincterotomy is not required when the distal (bottom) ends of metal stents are positioned within the duct, which may reduce the risk of poststenting cholangititis. Many authors disagree with endoscopic approaches to hilar strictures and advocate intubation for obstruction at this level by percutaneous methods (see Chapter 52; Paik et al, 2009).

Chronic Pancreatitis (See Chapter 55A, Chapter 55B )

Focal strictures of the main pancreatic duct may be stented to improve drainage and provide pain relief (Ponchon et al, 1995). As a rule, large diameter stents should be left in place, until the stricture either resolves or is significantly improved, but only in the face of well-established chronic pancreatitis. Persistent stenting has been used to achieve an adequate dilation effect with normalization of ductal caliber (Fig. 27.25). If the stricture is persistent or recurs, multiple stents can be placed to achieve greater dilation. Despite symptomatic improvement, the use of intraductal stents for prolonged periods is associated with a significant risk of duct damage (Somogyi & Forsmark, 1998). Migrated pancreatic duct stents can be managed with endoscopic balloon retrieval (Price et al, 2009).

FIGURE 27.25 Radiographs showing a high-grade stricture in the pancreatic head with upstream dilation (A) followed by balloon dilation (B) and placement of a pancreatic pigtail stent (C). Resolution of the stricture and normalization of pancreatic duct caliber after stent removal (D).

Stent Clogging

Clogging of plastic stents is a common problem that necessitates a stent exchange. The mean duration of patency of plastic biliary stents is approximately 5 months. Exploring ways to prolong stent patency has been the subject of considerable research over the years and remains unresolved. Expandable metal stents can be inserted through the duodenoscope in a compressed state and can expand to a diameter threefold that of plastic stents and are less prone to clogging (Weber et al, 2009b). Small diameter metal stents occlude more rapidly than large diameter stents (Loew et al, 2009). Conformable stents do not offer any better patency rate than nonconformable metal stents (Yang et al, 2009); and despite a need for fewer procedures with the use of metal stents, cost savings may not be significant (Yoon et al, 2009). Uncovered metal stents are not removable, which may present a problem if they become occluded, or if surgery is considered at a later time, and expandable stents should be reserved for unresectable malignant strictures. Covered metal stents may be removed, although with a significant complication rate (Mahajan et al, 2009).

Pancreatic stents occlude over time, but only a few patients become symptomatic (Buscaglia et al, 2009). The low incidence of pain or pancreatitis despite stent occlusion suggests that the stent functions as a wick around which pancreatic fluid continues to drain. In contrast to the bile duct, infection of the pancreatic duct (ductitis) is rarely seen as a complication of stent clogging.

Replacement of a clogged plastic stent can be performed by either removing the clogged stent with a snare or forceps and inserting a new stent or by exchanging the stent over a guidewire using a stent retriever (Fig. 27.26; Chaurasia et al, 1999). Foreign body forceps are used for biliary stents impacted in the wall of the duodenum. The metal spiral stent retriever is used when guidewire access to the bile duct is necessary.

FIGURE 27.26 Stent replacement using the Soehendra Retriever. A, With the aid of an endoscopic retrograde cholangioplasty catheter, a conventional 0.035-inch Teflon-coated guidewire is inserted through the prosthesis. B, The catheter is removed, and the Retriever is inserted over the wire, until it abuts against the distal end of the prosthesis. The stent is rotated clockwise to screw the Retriever tip into the prosthesis. C, The stent is removed over the indwelling guidewire.

(Courtesy Cook Medical, Winston-Salem, NC.)

Endoprosthesis for Stone Impaction

Failure to clear the duct of stones after sphincterotomy and ductal instrumentation places the patient at substantial risk for ductal infection (cholangitis, pancreatitis) and sepsis. Stent placement provides persistent drainage despite the presence of bile duct stones (Sharma et al, 2009). The placement of a 7- or 10-Fr endoprosthesis may be used as a temporizing measure to maintain drainage and prevent stone impaction pending more definitive management (Sharma et al, 2009). Stent placement also may be preferable to attempting stone extraction in a septic patient; clearance of the duct can be performed when the sepsis has resolved, and the patient’s condition has stabilized (Chopra et al, 1996). Stents should not be left in place as definitive treatment or over an extended time, because late complications, mainly cholangitis, have been reported. Surgical treatment of the problem must be considered when endoscopic techniques fail (see Chapters 29, 34, and 35).

Pseudocysts and Leaks

To determine whether a cyst communicates with the pancreatic duct, ERCP may be indicated in patients with pseudocysts that fail to resolve or those that recur (Lakhtakia & Reddy, 2009). Outflow obstruction secondary to a stricture, stone, or ampullary stenosis should be treated with sphincterotomy and/or stenting (Habashi & Draganov, 2009). Stenting also has been found to be effective in the management of partial and complete ductal leaks, fistulas, and ascites (Fig. 27.29; Kozarek et al, 1997). Endoscopic approaches to internal drainage of nonneoplastic pancreatic cysts are described in Chapter 14.

FIGURE 27.29 Radiographic views of a pancreatic duct leak at the neck region. A, Before stenting. B, After stenting.