Endoscopic ultrasound-guided anterograde cholangiopancreatography

Transcription

1 J Hepatobiliary Pancreat Sci (2011) 18: DOI /s TOPICS Advances in therapeutic ultrasound and endoscopy in hepato-biliary-pancreatic diseases Endoscopic ultrasound-guided anterograde cholangiopancreatography Kenneth F. Binmoeller Thai Nguyen-Tang Published online: 29 December 2010 Ó Japanese Society of Hepato-Biliary-Pancreatic Surgery and Springer 2010 Abstract Endoscopic retrograde cholangiopancreatography (ERCP) may fail in 10 15% of cases. A growing percentage of such cases are due to the inaccessible papilla after gastric bypass surgery for the treatment of obesity. Endoscopic ultrasonography (EUS) offers an alternative route of access to the bile and pancreatic ducts. Using the curved linear array echoendoscope, access to the bile and pancreatic ducts is possible under real-time EUS guidance. The route of access is anterograde, in contrast to the retrograde approach of ERCP. We have coined the term EUS-guided anterograde cholangiopancreatography (EACP) to cover the spectrum of EUS-guided techniques for accessing and draining the bile and pancreatic ducts. These techniques are reviewed in this paper. The literature has validated the feasibility of EACP but complication rates have been high; the safety profile of EACP must improve. This will require tools, designed for EUS-guided applications, that enable safer transenteric access and drainage. Keywords EUS-guided biliopancreatic therapy Endosonography-guided biliary and pancreatic drainage Anterograde biliary and pancreatic drainage Introduction Endoscopic retrograde cholangiopancreatography (ERCP) is the preferred way to drain an obstructed bile or K. F. Binmoeller (&) T. Nguyen-Tang Interventional Endoscopy Services, California Pacific Medical Center, San Francisco, CA, USA BinmoeK@sutterhealth.org pancreatic duct [1]. However, in 10 15% of cases, transpapillary drainage may not be feasible or may fail (Table 1). A growing percentage of these cases is due to the inaccessibility of the papilla after gastric bypass surgery to treatm obesity. When transpapillary drainage is not an option or fails, patients are usually referred for percutaneous drainage (for biliary obstruction) or surgical bypass (for biliary and pancreatic obstruction). These approaches carry significantly higher morbidity and mortality rates compared with ERCP and transpapillary drainage [2, 3]. Endoscopic ultrasonography (EUS) offers an alternative route of access to the bile and pancreatic ducts. Using the curved linear array (CLA) echoendoscope, access to the bile and pancreatic ducts is possible under real-time EUS guidance [4]. The route of access is anterograde, in contrast to the retrograde approach of ERCP. We have coined the term EUS-guided anterograde cholangiopancreatography (EACP) to cover the spectrum of EUSguided techniques for accessing and draining the bile and pancreatic ducts (Table 2). These techniques will be reviewed, including their indications, available data on efficacy and outcomes, and limitations. Procedure preparation and equipment Consent In our department, patients referred for therapeutic ERCP give consent for both ERCP and EACP, as it is impossible to predict when ERCP might fail and EACP will be required. Patients with known difficult anatomy (altered anatomy, gastric outlet obstruction) or prior failed ductal access are more likely to require EACP. EACP is performed in the same procedural session as ERCP by the

2 320 J Hepatobiliary Pancreat Sci (2011) 18: Table 1 Causes of failed retrograde access to the bile and pancreatic ducts Failed ductal cannulation Unidentifiable papilla Tumor infiltration of the papilla Juxtapapillary diverticulum High-grade stricture Difficult anatomy Inability to reach the papilla (or ductal anastomosis) Gastric outlet obstruction High-grade duodenal stenosis Post-peptic changes Post-surgical anatomy Gastrectomy Gastric bypass Whipple Hepaticojejunostomy Billroth II Table 2 Classification of EUS-guided pancreatobiliary interventions 1. Anterograde-retrograde access and downstream drainage (EUS-guided rendezvous procedure) 2. Anterograde access and upstream drainage EUS-guided hepaticogastrostomy EUS-guided choledochoduodenostomy EUS-guided pancreaticogastrostomy EUS-guided pancreaticoduodenostomy 3. Anterograde access and downstream drainage EUS-guided anterograde transpapillary stent placement EUS-guided anterograde transanastomotic stent placement same operator, thus avoiding the delay and expense of a second procedure (and sedation) session. Antibiotic coverage We routinely give antibiotics (ciprofloxacin or a third generation cephalosporin) prior to EACP. The rationale is to minimize the risk of peritonitis from leakage of ductal or enteric contents at the transmural puncture site. Oral antibiotics are continued for a minimum of 3 days after the procedure. Echoendoscope CLA echoendoscopes are commercially available with two channel sizes: small (standard) and large (therapeutic). The channel size determines the upper limit of the stent size that can be placed. The therapeutic CLA echoendoscope with a channel of 3.7 or 3.8 mm enables passage of a 10 Fr stent. A standard CLA echoendoscope with channel size of 2.8 mm allows passage of a 7 Fr stent. In our unit we use the therapeutic CLA echoendoscope for all EACP interventions to keep all options open. Although a therapeutic CLA echoendoscope is not required for a rendezvous procedure (the echoendoscope is exchanged for a duodenoscope for stent placement), the guidewire may fail to cross the stricture and/or ampulla, in which case rescue upstream transenteric stent drainage, performed through the echoendoscope, will be required. Ductal access A conventional FNA needle can be used to access the bile or pancreatic duct. The choice of FNA needle size depends on the clinical context, the goal of the procedure, and the ductal anatomy. Our default needle size is 19 gauge, through which a inch, 400-cm long wire can be inserted. The drawback of the 19 gauge needle is its relative stiffness, which results in a very tangential angle of puncture. The elevator, when activated, has virtually no effect on the puncture angle. It is also difficult to penetrate indurated tissue with the 19 gauge needle. We rarely use the 22 gauge needle, as it only accepts a inch guidewire. This wire is inadequate for EUS-guided intervention because it: (1) is hard to see on fluoroscopy; (2) is hard to steer; and (3) lacks the stability and trackability required for over-the-wire intervention. The only instance where a 22 gauge needle may be required is when targeting of a nondilated duct (e.g., intrahepatic or pancreatic) with the 19 gauge fails. The inch wire will need to be exchanged for a inch wire through a catheter. A 25 gauge needle does not accept a wire but it might be considered when the goal is a diagnostic cholangiogram or pancreatogram in a patient with a coagulation disorder or low platelet count. An alternative to using the FNA needle to achieve ductal access is the diathermic needle knife with removable inner needle (Zimmon needle knife, Cook Medical). Pure cutting current is applied during puncture to penetrate tissue. The advantage of using the needle knife is the ability to immediately exchange the inner needle for a guidewire. The outer catheter can then be easily steered in the duct, off-axis from the angle that the duct was punctured. A drawback of the needle knife is the limited visibility of the needle at the catheter tip, both on ultrasound and fluoroscopy. Another drawback is the risk of diathermy trauma to tissue, which is a particular concern should the needle veer off course during puncture. Whereas a continuous stainless steel needle will maintain the predicted trajectory path as it is advanced, the more flexible needle knife catheter may veer off-axis into a neighboring structure, which may be a major vessel.

3 J Hepatobiliary Pancreat Sci (2011) 18: Guidewires The guidewires used in EACP are the same as those used in ERCP. We routinely start with the inch hydrophilic Glidewire inserted through a 19 gauge needle. As in ERCP, the hydrophilic Glidewire has excellent steerability to negotiate tortuous ducts and high-grade strictures. The low coefficient of friction, however, is a drawback for over-thewire exchange of accessories. During the rendezvous procedure, extreme care must be taken that the Glidewire does not slip back during the withdrawal of the echoendoscope and insertion of the duodenoscope. One can exchange the Glidewire through a standard ERCP catheter for a stiffer instrumentation wire, but this requires advancement of the catheter across the bowel lumen and obstruction. A 22 gauge needle will only accept a inch guidewire. As mentioned above, the inch guidewires lack the stability and trackability required for over-the-wire intervention. In the United States, the hydrophilic Glidewire is only available in a inch size, which creates too much friction between the wire and needle. Even if the inch size were available, the Glidewire is barely visible on fluoroscopy at this size and therefore not likely to be useful. Tract dilation Dilation is required prior to stenting. As in ERCP, graduated bougies and non-compliant balloon catheters can be used. Each has pros and cons. Bougies have the advantage of excellent operator control of the dilation force, as the operator can gauge the amount of resistance encountered during advancement of the bougie, However, the dilation force is axial, which can lead to a separation of tissue planes during bougie advancement. Balloons have the advantage that they can be inserted in a compressed state, thereby minimizing the delivery catheter size to around 5 Fr. Upon balloon inflation, the dilation force is radial. However, balloons dilate to a fixed diameter in an all-or-nothing fashion which increases the risks of perforation and bleeding. It is noted that the size of the bougie or balloon should not substantially exceed the size of the stent to be inserted in order to minimize the risk of transmural leakage of ductal and enteric contents. This is a consideration when deciding whether to dilate with a bougie or balloon, as the smallest dilation balloon size is 4 mm (12 Fr). Occasionally, passage of a balloon or bougie across the bowel wall after guidewire access may fail. If this happens, a smaller profile catheter, such as a finely tapered ERCP catheter, can be used to prime the tract for dilation. If this fails, penetration can be facilitated with diathermy using a double lumen needle knife catheter. Alternatively, a catheter with a diathermic ring at the tip can be used. Endoscopists in Europe have used a 6.5 Fr diathermic ring device (Endoflex, Voerde, Germany) with good results. Currently, only a 10 Fr diathermic ring device (Cystotome CST10; Cook Medical) is approved for use in the United States. The Cystotome was designed for endoscopic transmural puncture of large pseudocysts and has been successfully used for this indication, but there is no reported experience for puncture of the bile or pancreatic ducts. The Cystotome is a rigid device that is difficult to advance across the oblique exit of the working channel of the therapeutic CLA echoendoscope. Stents The choice of stent type, size and length depends on the ductal anatomy. Again, as in ERCP, straight and pigtail plastic stents and self-expandable metal stents (SEMS) can be used. Pigtail stents are a logical choice to minimize the risk of stent migration (especially into the duct), but the pigtail end makes stent insertion more difficult owing to a weakened coaxial transfer of force. We therefore prefer to use straight stents for transenteric drainage. We have not found migration to be a problem when the flaps are deployed properly. A further advantage of a straight stent is the ability to retrieve or exchange the stent over the wire without loss of ductal access. Covered SEMS have been used for transenteric drainage, but may migrate, particularly with shortening [5]. The covering may block drainage of a secondary duct (e.g., cystic duct or intrahepatic branch). Uncovered SEMS are generally unsuited for transenteric drainage due to leakage between the struts. Uncovered SEMS can be placed in exchange for a temporary plastic stent after the fistula tract has matured (Fig. 2f). We always use SEMS when a malignant stricture can be traversed and drained downstream. This is justified since plastic stent clogging is likely to require a repeat EACP procedure. EUS-guided puncture It is helpful to fluoroscopically assess the position of the echoendoscope before puncturing the duct. The exit path of the needle should be oriented towards the downstream portion of the duct. To access the left hepatic bile duct, the scope is positioned in the proximal stomach along the lesser curve. To access the proximal and distal extrahepatic bile ducts, the scope is positioned in the mid-stomach and duodenal bulb, respectively. In the duodenal bulb, it may be necessary to shift from a long to a short position; in the long position the needle tends to orient towards the upstream bifurcation, whereas in the short position the needle orients towards the downstream ampulla. A trade-off of the short position is that it can be unstable, with a tendency for the echoendoscope to fall back into the stomach. Transhepatic access is generally preferrable to extrahepatic access due to the protection afforded by the liver

4 322 J Hepatobiliary Pancreat Sci (2011) 18: Fig. 1 EUS-guided rendezvous. Presentation with jaundice. Upper endoscopy showed a large fungating ampullary tumor. Biopsies confirmed adenocarcinoma. ERCP was attempted, but failed to access the bile duct. a Under EUS-guidance a dilated left intrahepatic duct is punctured with a 19 gauge FNA needle (arrow). b After aspiration of bile, contrast is injected under fluoroscopy. A distal bile duct stricture is seen (arrow). c A inch hydrophilic guidewire is advanced across the stricture and looped in the duodenal lumen. d After exchange of the echoendoscope for a duodenoscope, the guidewire is seen exiting the ampullary tumor. e The guidewire is grasped with a snare and pulled through the channel of the duodenoscope. f A 10-Fr biliary plastic stent is successfully placed over the wire parenchyma against complications of a bile leak (as is well known from percutaneous transhepatic access). The extrahepatic route has the advantage of easier, more direct access. It is usually easier to access the extrahepatic bile duct from the duodenal bulb. The bile duct runs along the duodenal wall as it emerges from the pancreatic head (this is also the location used by surgeons to create a choledochoduodenostomy). The portal vein is usually deep to the bile duct and therefore not in the needle path. The pancreatic duct can be punctured at virtually any point along its length from the stomach to the duodenal bulb. It is easiest to access the junction of the neck to body region from the stomach. The initial puncture point should not be too close to the stricture in order to have some distance to steer the guidewire through the stricture. Analogous to transhepatic drainage, the pancreatic parenchyma surrounding the pancreatic duct is thought to protect against complications of a possible leak from the pancreatic duct.

5 J Hepatobiliary Pancreat Sci (2011) 18: Anterograde-retrograde access and downstream drainage (rendez-vous procedure) The rendezvous procedure is derived from the percutaneous technique whereby a guidewire is passed anterogradely across the stricture and papilla (or surgical anastomosis) for subsequent rendezvous retrograde drainage by ERCP [6]. Percutaneous access under fluoroscopic guidance is substituted for transgastric or transduodenal access under EUS-guidance. This procedure minimizes the role of interventional EUS and should be considered an advanced cannulation technique for ERCP (Fig. 1). Procedure 1. At the time of initial endoscopy, a clip is placed adjacent to the papilla to mark its location. 2. For bile duct access, we first attempt a transhepatic approach from the stomach with a 19 gauge FNA needle. The stomach provides an excellent window to image and access the left hepatic ducts. The surrounding hepatic parenchyma acts as a sponge to absorb and minimize bile leakage. If transhepatic access fails, we puncture the extrahepatic bile duct from the duodenum or stomach using a 22 gauge FNA needle. 3. Bile or pancreatic juice is aspirated to confirm access. 4. Contrast medium is injected to obtain a ductogram, delineate the ductal anatomy, and show relevant pathology. 5. Fluoroscopic guidance is used for anterograde passage of a guidewire through the FNA needle across the stricture and across the papilla, identified by the previously placed clip. The guidewire is advanced to form 2 3 loops in the duodenal lumen. 6. The FNA needle is removed while leaving the wire in place. The elevator is closed to help anchor the position of the wire. 7. The echoendoscope is removed over the wire under fluoroscopic monitoring taking care that the wire remains looped in the duodenum. 8. The esophagus is intubated with the duodenoscope alongside the wire. The duodenoscope is advanced to the papilla where the wire exiting the papillary orifice is grasped with a snare and pulled through the accessory channel. 9. The wire is retracted until it clears the site of transmural puncture and lies completely within the duct. Standard ERCP intervention and stenting is performed over the wire. The duct should be adequately decompressed to minimize the risk of bile leakage at the transmural puncture site. 10. In patients with post-surgical anatomy (Billroth II or Roux-en-Y) a colonoscope or enteroscope may be used to complete the ERCP procedure. Available data About a hundred cases of successful EUS-guided rendezvous procedures performed for pancreatobiliary obstructions have been reported in the literature (Table 3). Success rates vary between 35 and 78% in the largest cases series. EUS-guided puncture of the duct and ductography are accomplished in most cases. Failure is mainly due to inability to steer a guidewire across the stricture. A rescue upstream transenteric drainage is then performed to drain the obstructed duct. When combining attempted EUS-guided rendezvous and upstream drainage in cases of failure, the overall drainage success rate is 87%. The reported complication rates are 12 17% and include bile leaks, self-resolving pneumoperitoneum, subcapsular hematoma and post-procedure pancreatitis. Limitations and challenges The rendezvous procedure is limited by two requirements: (1) an endoscopically accessible papilla (or bilio-enteric anastomosis); and (2) successful passage of the guidewire across the stricture into the downstream small bowel. Accessing the bile duct with a wire is easy, but manipulating the wire within the duct and across the stricture can be difficult when the axis of the needle and the downstream bile duct lumen are not aligned. The wire tends to catch at the needle tip during to-and-fro manipulation, and may even shear off with forceful wire retraction. Bile, which is viscous and sticky, contributes to friction between the wire and needle. As the rendezvous procedure requires an exchange of the echoendoscope for a duodenoscope, it is easy to lose wire access during the exchange. Keeping the wire looped several times in the duodenal or jejunal lumen will help anchor the wire s position. The process of pulling the wire through the working channel of the duodenoscope requires patience; if the snare catheter is pulled too forcefully, the wire will slip through the closed snare. The wire can also exert traumatic shearing forces along the bile duct and liver. Anterograde access and upstream transenteric drainage Ductal access is similar to that of EUS-guided rendezvous, upstream transenteric drainage is performed when the stricture cannot be traversed with a wire or when the papilla or surgical anastomosis cannot not be reached with an

6 324 J Hepatobiliary Pancreat Sci (2011) 18: Table 3 Studies evaluating EUS-guided rendezvous and anterograde drainage No. of cases Biliary/pancreatic drainage Successful rendezvous biliary/pancreatic Successful drainage biliary/pancreatic Complications related to the procedure Bataille et al. [12] 1 0/1 0/1 (100%) 0/1 (100%) None Mallery et al. [13] 6 2/4 2/1 (50%) 2/1 (50%) Transient fever (1) Kahaleh et al. [14] 5 5/0 3/0 (60%) 4/0 (80%) None Will et al. [15] 1 0/1 0/1 (100%) 0/1 (100%) None Kahaleh et al. [16] 6 6/0 4/0 (67%) 5/0 (83%) None Kahaleh et al. [17] 23 23/0 18/0 (78%) 21/23 (91%) Bleeding (1) Bile leak (1) Pneumoperitoneum (2) Tarantino et al. [18] 9 9/0 4/0 (44%) 9/0 (100%) None Brauer et al. [19] 20 12/8 4/3 (35%) 11/7 (90%) None Maranki et al. [20] 49 49/0 32/0 (65%) 41/0 (84%) Bleeding (1) Bile leak (1) Pneumoperitoneum (4) Our data [21, 22] 54 43/11 24/4 (71%) 31/9 (74%) Pancreatitis (4) Subcapsular hematoma (1) Bile leak (1) endoscope. For biliary drainage, the transhepatic route (hepaticogastrostomy, Fig. 2) is preferred due to a lower risk of bile leak complications. There are theoretical advantages to creating a fistula that is upstream from the obstructing stricture: the stent is not subject to tumor ingrowth or overgrowth, and there should be a lower propensity to clogging (Figs. 2, 4). Procedure technique 1. The obstructed duct is punctured under EUS-guidance with a 19 gauge needle. 2. Bile or pancreatic juice is aspirated to confirm access. 3. Contrast is injected to obtain a ductogram and delineate the ductal anatomy. 4. Fluoroscopic guidance is used for anterograde advancement of a stiff inch guidewire. 5. The needle is removed with the wire left in place. 6. The tract is dilated with bougies up to the size of the stent to be inserted. If transmural advancement of the bougie fails, a double lumen needle knife is used to apply diathermy during advancement of the catheter. 7. A straight plastic stent is placed over the wire. The plastic stent can be exchanged for an SEMS at a later session after the tract matures. Available data The available data on EUS-guided hepatico-gastrostomy is summarized in Table 4. Only 22 cases have been reported in the literature with a high rate of technical success exceeding 90%. The overall complication rate is 22% and includes cholangitis, bilioma, ileus and stent occlusion. Both plastic and metal stents have been used for transenteric drainage. Bories et al. [5] reported two cases of peritoneal leak caused by shortening of the metal stent after deployment. The available data on EUS-guided choledochoduodenostomy is summarized in Table 5. Thirty-four cases have been reported and the overall success rate of the procedure is high (89%) but a high complication rate (21%) is also noted. The reported complications include 5 pneumoperitoneums (15%) and 2 bile leaks (6%). In the majority of cases plastic stents were used to drain the common bile duct into duodenum. The available data on EUS-guided pancreaticoenterostomy is addressed below. Limitations and challenges The main limitation of transhepatic drainage is the lack of adherence between the stomach and the liver. A shift in the liver s position relative to the stomach wall may cause the stent to dislocate, resulting in a bile leak into the peritoneal space. The lack of adherence also increases the risk of bleeding from the liver surface. Similarly, the main drawback of a choledocho-enterostomy is the absence of adherence between the bile duct and the bowel wall. As seen from the literature, there is a very high risk of bile leak

7 J Hepatobiliary Pancreat Sci (2011) 18: Fig. 2 EUS-guided hepaticogastrostomy. Presentation with painless jaundice. Abdominal CT showed a hypodense mass in the head of the pancreas. EUS fine needle aspiration confirmed a locally advanced adenocarcinoma. ERCP was attempted but failed to access the duct because of a duodenal stricture with severe periampullary inflammation. a Transhepatic puncture of a dilated left hepatic duct with a 19G FNA needle (arrow). b Cholangiogram shows complete obstruction at the distal bile duct stricture (arrow). Despite numerous manipulations, the inch hydrophilic guidewire could not be passed across the stricture (arrow). A previously placed clip marking the location of the ampulla is seen (arrow). c The tract is dilated with a bougie (arrow). d A 8.5-Fr hepaticogastric stent is successfully placed. e The position of the stent (arrow) is confirmed on fluoroscopy and shows that the retained contrast has drained. f Six weeks later the plastic stent is exchanged for an 8 mm x 6 cm uncoated selfexpandable metal stent (Wallflex, Boston Scientific) and pneumoperitoneum. Compounding this, intraductal pressures are higher in the extrahepatic bile duct than in the intrahepatic duct. Post-surgery anatomy can pose obvious limitations for transenteric drainage. Left hepatectomy eliminates transhepatic access, prior gastrojejunostomy or biliary bypass surgery (hepaticojejunostomy) eliminates extrahepatic access. There is limited experience regarding the management of an occluded stent. If a mature tract has formed, stent replacement may not be required. However, it is unknown how long it takes for a mature tract to form, or whether an unstented tract will close over time. For long-term stenting, our preference is to exchange a straight plastic stent over the wire for an SEMS. Larger series with longer follow-up are needed to determine the optimal drainage strategy using plastic and metal stents. Anterograde access and downstream drainage EUS-guided anterograde biliary SEMS placement This procedure is derived from percutaneous internal stent drainage performed by interventional radiologists [8, 9]. The prerequisite for EUS-guided anterograde

8 326 J Hepatobiliary Pancreat Sci (2011) 18: Table 4 Studies evaluating EUS-guided hepaticogastric drainage No. of cases Puncture and dilation devices Stent placed Technical success (%) Clinical success (%) Complications related to the procedure Burmester et al. [23] 1 Fistulotome Plastic None Giovaninni et al. [24] 1 19 gauge needle Plastic None Needle knife Kahaleh et al. [17] 1 19 or 22 gauge needle Plastic None Artifon et al. [25] 1 19 gauge needle SEMS None Will et al. [26] 4 19 gauge needle SEMS Cholangitis (1) 6 Fr bougie and 4- or 6-mm balloon Bories et al. [5] or 22 gauge needle 6 or 8.5 Fr cystotome Plastic (7) SEMS (3) Ileus (1) Stent occlusion (1) Bilioma (1) Cholangitis (1) Maranki et al. [20] 3 19 or 22 gauge needle Plastic Not available Table 5 Studies evaluating EUS-guided choledochoduodenal drainage No. of cases Puncture and dilation devices Stent placed Technical success (%) Clinical success (%) Complications related to the procedure Giovannini et al. [27] 1 Needle knife Plastic None Dilating catheter Burmester et al. [23] 2 Fistulotome Plastic Bile peritonitis (1) Puspok et al. [11] 5 Needle knife Plastic None Kahaleh et al. [17] 1 19 gauge needle SEMS Pneumoperitoneum (1) Fujita et al. [28] 1 19 gauge needle Plastic None Dilating catheter Ang et al. [29] 2 Needle knife Plastic Pneumoperitoneum (1) Dilating catheter Yamao et al. [30] 5 Needle knife Plastic Pneumoperitoneum (1) Dilating catheter Tarantino et al. [18] 4 19 gauge or 22 gauge needle Plastic None Balloon dilation Itoi et al. [31] 4 19 gauge needle or Needle knife Plastic Bile peritonitis (1) Dilating catheter or Balloon dilation Maranki et al. [20] 4 19 gauge needle NA NA NA NA Dilating catheter or Balloon dilation Brauer et al. [19] 3 19 gauge or 22 gauge needle Plastic Pneumoperitoneum (1) Our data [21] 2 Needle knife SEMS Pneumoperitoneum (1) NA Not available biliary SEMS placement is the successful traversement of the stricture with a guidewire. Cases have been reported in patients with malignant strictures and an endoscopically inaccessible papilla or bilioenteric anastomosis (Fig. 3). Procedure technique 1. EUS-guidance is used to puncture the obstructed duct with a 19 gauge needle. 2. Bile is aspirated to confirm biliary access.

9 J Hepatobiliary Pancreat Sci (2011) 18: Fig. 3 EUS-guided anterograde SEMS placement. Presentation with jaundice, post right hepatectomy and Roux-en-Y hepaticojejunostomy for cholangiocarcinoma. The hepaticojejunostomy could not be reached with the double balloon enteroscope. a CT showing liver metastases and dilated ducts in the residual left lobe. b Cholangiogram after EUS-guided puncture of the left intrahepatic ducts. A inch hydrophilic guidewire is advanced across the strictured hepaticojejunostomy into the jejunal loop (arrow). c The tract is dilated with a bougie catheter (arrow). d A10mm9 6cm metal stent is deployed anterograde across the stricture (arrow) 3. Contrast is injected to obtain a ductogram and delineate the ductal anatomy. 4. Fluoroscopic guidance is used for anterograde advancement of a inch hydrophilic guidewire across the stricture. 5. The 19 gauge needle is removed with the wire left in place. 6. The tract is dilated with a 7 Fr bougie catheter. 7. The hydrophilic guidewire is exchanged for a inch instrumentation wire through the bougie catheter. 8. A biliary SEMS is advanced over the guidewire with deployment across the stricture and downstream papilla or anastomosis. Available data We recently reported a series of 5 patients who underwent anterograde biliary SEMS placement because of a nontraversable high-grade duodenal stricture (n = 4) and an endoscopically unreachable biliary anastomosis in a patient with a hepaticojejunostomy (n = 1) [10]. The SEMS was successfully deployed with a decrease in bilirubin levels in all cases. No post-procedural complications were noted after a median follow-up of 9.2 months. Puspok et al. [11] previously described a successful EUS-guided transhepatic SEMS in a single patient with a malignant biliary obstruction following gastrectomy and Roux-en-Y anastomosis. Bories et al. [5] successfully placed an SEMS transhepatically and under EUS guidance in 2 patients. However, these procedures were performed in a two-stage fashion with initial creation of a hepaticogastrostomy tract followed by anterograde placement of an SEMS in a second procedure. Limitations and challenges The right biliary system is not accessible to this method of drainage and the presence of dilated ducts is necessary. Due to the limited available data, further studies are warranted to confirm the efficacy and safety of this technique. EUS-guided pancreatic duct drainage The main indications for EUS-guided drainage of the pancreatic duct are symptomatic obstruction due to chronic pancreatitis, post-surgical stricture of the pancreaticojejunal anastomosis, or a ductal disruption. The puncture site varies depending on the site of the stenosis. In most cases the main pancreatic duct is targeted from the stomach (transgastric route). The easiest transmural access to the pancreatic duct is at the junction of the genu and body. Puncturing a non- or minimally dilated pancreatic duct can be difficult with a 19 gauge needle and may require a 22 gauge needle. The penetration of fibrosed pancreatic parenchyma is also facilitated by a 22 gauge needle. However, the 22 gauge needle takes only a inch wire, which is difficult to see and to guide. There is also a tendency for the guidewire to enter side branches. Drainage

10 328 J Hepatobiliary Pancreat Sci (2011) 18: Fig. 4 EUS-guided pancreaticogastrostomy. Presentation with painful chronic pancreatitis. ERCP was attempted but a wire failed to cross a tight pancreatic duct stricture in the head. a EUSguided puncture of a dilated pancreatic duct in the genu region with a 19G needle (arrow). b A inch hydrophilic guidewire failed to traverse the stricture. Fluroscopic (c) and endoscopic (d) views of a 7 Fr 9 7cm straight pancreatic stent (arrow), inserted after tract dilation with bougie catheters can be accomplished using a rendezvous approach if the stricture can be negotiated with a wire and the papilla or pancreaticojejunostomy can be reached with the endoscope. Failing this, transenteric drainage is performed. The procedure steps are similar to those of hepaticogastrostomy outlined above. Our preference is to use a straight 7 Fr stent for transgastric drainage. We replace the single stent with two 7 Fr stents if there is recurrence of symptoms (Fig. 4). Available data The reported data are summarized in Table 6. A total of 72 patients underwent EUS-guided pancreatic drainage. The pancreatic duct was accessed and drained in the majority of patients via the transgastric route. The technical success rate was 91% with a complication rate of 15%. Complications included post-procedural pain (n = 4), bleeding (n = 3), perforations (n = 3) and pancreatitis (n = 1). Tessier et al. [7] reported stent dysfunction requiring repeat endoscopies during the a median follow-up of 14.5 months 55%. Limitations and challenges The technical challenges relate to the fibrotic changes of chronic pancreatitis, which make needle penetration of the pancreas and tract dilation difficult. As mentioned, a 22 gauge needle can be used to achieve penetration and duct access, but leads to a second hurdle of tract dilation for stent drainage. The smallest bougies and balloons advanced over a wire usually fail to penetrate the pancreas and will buckle. One solution is to use cautery with a double lumen needle knife or diathermic ring device. The risks, including pancreatitis, leakage, and perforation, remain to be defined in larger studies. EACP versus PTCD EACP has a number of theoretical advantages over percutaneous transhepatic cholangiodrainage (PTCD). Drainage is internal, and thereby eliminates problems with external percutaneous drainage, including local skin pain, infection, drain care, and bile loss. EACP is not limited by obesity, and less limited by ascites than PTCD. Ultrasound guidance and the use of color Doppler improves the safety profile of EACP by avoiding vessels. Practical advantages are the ability to perform EACP in the same session as a failed ERCP. In our department ERCP and EACP are performed by the same operator. EACP provides excellent access to the left lobe, which can be limited by PTCD. However, access to the right

11 J Hepatobiliary Pancreat Sci (2011) 18: Table 6 Studies evaluating EUS-guided pancreatic drainage No. of cases Puncture and dilation devices Drainage route Technical success (%) Complications related to the procedure François et al. [32] 4 19 gauge needle Transgastric 100 None Cystotome Kahaleh et al. [33] 2 19 gauge needle Transgastric 100 None Balloon dilation Kahaleh et al. [34] gauge or 22 gauge needle Balloon dilation Transgastric 83 Bleeding (1) Perforation (1) Tessier et al. [7] 36 19, 22 gauge needle or cystotome Transgastric (29) Transduodenal (7) 92 Pancreatitis (1) Hematoma (1) Will et al. [35] gauge needle Dilating catheter and stent retriever Transgastric 69 Pain (4) Bleeding (1) Perforation (1) Our data [21] 5 19 gauge needle Dilating catheter Transgastric 100 Perforation (1) Ampulla or bilioenteric anastomosis accessible? YES EUS-Guided Rendezvous NO Anterograde access Stricture traversable? YES Downstream drainage NO Upstream drainage Fig. 6 Algorithm for EUS-guided interventions when ERCP access fails Fig. 5 Lumen-apposing stent (AXIOS, Xlumena Inc) lobe with EACP is limited. EACP uniquely provides access to the pancreatic duct. EACP versus ERCP There are theoretical advantages of EACP over ERCP. By avoiding the ampulla and accidental cannulation or injection of the pancreatic duct, EACP eliminates any risk of pancreatitis. The problem of difficult cannulation is also eliminated. Anterograde transenteric drainage eliminates all instrumentation (wire passage, dilation and stenting) of the downstream stricture. Creating a natural fistula at a distance from the obstructing tumor solves the problem of tumor ingrowth and overgrowth which can cause stent obstruction, and it may solve the problem of stent clogging. Future developments Tubular stents that are currently used to accomplish endoscopic translumenal drainage do not impart lumento-lumen anchorage. What is needed is a lumen-apposing stent that enables the creation of a leak-proof conduit between nonadherent lumens such as the bile duct and the duodenum (choledochoduodenostomy). In the porcine model, a fully covered expandable lumen-apposing stent (AXIOS, Xlumena Inc, Mountainview, CA) was tested and found to create a safe, durable, leak-free conduit (Fig. 5). The stent was easily removable at 4 weeks [36]. Future developments should enable the integration of the multiple steps required to achieve translumenal ductal drainage into a single catheter-based device. After lumen access, tract dilation and stent deployment should occur seamlessly in a co-axial fashion without instrument exchanges.

12 330 J Hepatobiliary Pancreat Sci (2011) 18: Conclusion Over recent years, we have seen the emergence of EACP as a viable strategy to achieve drainage of the bile and pancreatic ducts when ERCP is not feasible or fails. The algorithm in Fig. 6 outlines the use of EACP in our department. For biliary drainage, EACP has numerous theoretical advantages over PTCD. For pancreatic duct drainage, EACP offers a less invasive alternative to pancreatic bypass surgery. The literature has validated the feasibility of EACP but complication rates have been high and the safety profile of EACP must be improved. This will require improvements in device development and training. It must be emphasized that the tools used to perform EACP have been borrowed from ERCP and other sectors of interventional endoscopy. Tools designed for EUS-guided applications that enable safer transenteric access and drainage are needed. The input from innovative device manufacturers is critical at this stage. 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