Over the last 2 decades there has been continuing development in endoscopic ultrasonography (EUS). EUS-guided pancreatic drainage is an evolving procedure that can be offered to patients who are high-risk surgical candidates and in whom the pancreatic duct cannot be accessed by endoscopic retrograde pancreatography. Although EUS-guided pancreatic drainage is a minimally invasive alternative option to surgery and interventional radiology, owing to its complexity and potential for fulminant complications it is recommended that these procedures be performed by highly skilled endoscopists. Additional data are needed to define risks and long-term outcomes more accurately via a dedicated prospective registry.
Key points
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Endoscopic ultrasonography–guided techniques for drainage of the pancreatic duct continue to evolve as less invasive alternatives to surgery.
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Drainage of the pancreatic duct can be transluminal or transpapillary, with or without the rendezvous technique.
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This method is technically challenging and requires advanced expertise.
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Complications can be severe.
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Dedicated devices are needed to improve the safety profile and efficacy.
Introduction
Endoscopic retrograde pancreatography (ERP) is the conventional method for evaluating and treating obstruction of the pancreatic duct caused by strictures, stones, or congenital anomalies such as pancreatic divisum. Even in expert hands, ERP is not technically possible in approximately 3% to 10% of patients, owing to surgically altered anatomy, tight strictures, complete ductal obstruction, or a disrupted duct. Surgery and/or interventional radiology alternatives have been posited, with their known respective morbidity. Over the last 2 decades there has been continuing development in endoscopic ultrasonography (EUS) with therapeutic techniques, such as celiac plexus block and EUS-guided pseudocyst or abscess drainage, replacing surgical or radiologic interventions. EUS-guided pancreatic drainage was the next step on this continuum. EUS-guided pancreatic drainage methods include anterograde or retrograde pancreatography with drainage and the rendezvous procedure.
Introduction
Endoscopic retrograde pancreatography (ERP) is the conventional method for evaluating and treating obstruction of the pancreatic duct caused by strictures, stones, or congenital anomalies such as pancreatic divisum. Even in expert hands, ERP is not technically possible in approximately 3% to 10% of patients, owing to surgically altered anatomy, tight strictures, complete ductal obstruction, or a disrupted duct. Surgery and/or interventional radiology alternatives have been posited, with their known respective morbidity. Over the last 2 decades there has been continuing development in endoscopic ultrasonography (EUS) with therapeutic techniques, such as celiac plexus block and EUS-guided pseudocyst or abscess drainage, replacing surgical or radiologic interventions. EUS-guided pancreatic drainage was the next step on this continuum. EUS-guided pancreatic drainage methods include anterograde or retrograde pancreatography with drainage and the rendezvous procedure.
Background
Obstruction of the main pancreatic duct caused by strictures, stones, or anatomic anomalies is typically treated by ERP, interventional radiology, or surgical drainage. It is thought that the obstruction to the flow of pancreatic juices causes high pressures in the pancreatic duct, which lead to pain. Pharmacologic pain management and celiac plexus block are often used in an attempt to relieve pain, but do not address the obstruction. In symptomatic patients with obstruction of the pancreatic duct and retention of pancreatic juice within the pancreatic duct, ERP with drainage is considered the primary therapy. Indications for drainage of the pancreatic duct include chronic pancreatitis, groove pancreatitis, post-Whipple strictures, disrupted pancreatic duct after acute pancreatitis or trauma, pancreatic fistula and ascites, and endoscopic snare ampullectomy when prophylactic stent insertion has failed.
Before performing pancreatic decompression, a tumor should be excluded as a possible cause of pancreatic obstruction, and adequate sampling of the pancreatic stricture should be performed. Decompression of the duct using ERP leads to complete or partial relief in 60% to 80% of patients. In 5% to 10% of these patients, the pancreatic duct cannot be drained via ERP. Reasons for failure include postinflammatory changes of the periampullary region, pancreatic divisum with a stenotic minor papillary orifice, surgically altered anatomy, and gastric outlet or duodenal obstruction. Patients who fail ERP may require interventional radiology, surgery, or enteral feeding until the acute flare is resolved.
Surgical interventions permit both ductal decompression and pancreatic resection, if indicated. The type of surgery is typically determined by the anatomy of the pancreatic duct. In patients with a dilated main pancreatic duct, a lateral pancreaticojejunostomy is performed. Resection of the diseased portion of the pancreas is indicated when there is focal disease, particularly in the absence of pancreatic ductal dilatation. In these cases a Whipple procedure, a duodenum-preserving resection of the pancreatic head, or distal pancreatectomy is performed. Total pancreatectomy with auto–islet cell transplantation has been recommended for patients with chronic pancreatitis with adequate endocrine reserve, and seems to be the most appropriate option for patients failing endoscopic treatment.
However, surgical interventions have limitations. Lateral pancreaticojejunostomy has a high complication rate (range, 6%–30%) and mortality rate (range, 0%–2%). Up to 20% of patients develop recurrent pain from inadequate drainage. Pain may occur after pancreatic resection owing to the development of anastomotic strictures, which occur in approximately 5% of patients undergoing a Whipple procedure. Steatorrhea occurs in 30% to 40% of patients undergoing drainage procedures and in up to 60% of patients requiring pancreatic resections. Diabetes can occur after pancreatic resection as a consequence of surgery or progression of the disease state.
In patients with a high operative risk or those who decline surgical intervention, EUS-guided pancreatic drainage is a promising alternative diagnostic and therapeutic option. With the evolution of the linear-array echoendoscopy, and the ability to direct a needle within the field of intervention, the biliary and pancreatic ducts become reasonable targets for EUS when not accessible by conventional endoscopic retrograde cholangiopancreatography (ERCP). The method of EUS-guided pancreatography was first described by Harada and colleagues in 1995 as a case report of a patient requiring removal of a pancreatic duct stone following pancreaticoduodenectomy.
Since then, interventional endosonography has been described as a platform for access to and drainage of the pancreatic duct either by rendezvous or transmural drainage. The rendezvous technique combines EUS with ERP by puncturing the dilated pancreatic duct under EUS guidance with insertion of a guide wire into the duct, then exiting the papilla. Data show that rendezvous is often unsuccessful, and patients may require transluminal drainage with either pancreaticogastrostomy or pancreaticoduodenostomy.
Methods
Procedure Considerations
Only experienced endoscopists trained in EUS and ERCP should attempt this procedure. If ERP initially fails, the patient should be referred to a tertiary care center with expertise in ERCP. Before considering EUS-guided drainage, various methods to obtain pancreatic access should be attempted including standard cannulation techniques, hydrophilic guide wires, or needle knife precut sphincterotomy of the major and/or minor papilla. Dedicated pancreaticobiliary surgeons should be available in the event of complications.
Patient Selection and Evaluation
Specific informed consent for EUS-guided pancreatic drainage should be obtained from all patients after a detailed discussion of the indications, risks, benefits, and alternatives to the procedure. Cross-sectional imaging should be reviewed and eventually repeated, if inadequate, before the procedure, to use as a roadmap. All procedures should be performed under general anesthesia with fluoroscopic guidance. Carbon dioxide is exclusively used for insufflation. Antibiotics are administered as a prophylactic measure.
Materials and Instruments
A therapeutic channel linear-array echoendoscope with a large working channel (3.8 mm) is needed to allow the use of a broad variety of accessories and to allow for the insertion of large-caliber stents (10F).
If the goal of the procedure is to perform ductography, it may be advantageous to use a smaller-gauge needle to determine whether contrast freely flows across the stricture, a finding suggesting absence of critical stenosis and precluding therapeutic intervention. For interventional cases, a 19-gauge fine-needle aspiration (FNA) needle should be used, offering the ability to manipulate a larger 0.025-in (0.635 mm) or 0.035-in (0.889 mm) guide wire, which may facilitate crossing strictures and promote passage of other accessories. 0.035-in wires have maximal stiffness but may be subject to shearing at the tip of the 19-gauge needle. The authors do not recommend using a 0.018-in (0.457 mm) guide wire because such wires are floppy and can make interventions challenging. For difficult stenoses or angles, a hydrophilic wire or an angled wire may facilitate traversal of narrowed or tortuous segments.
Technique
The technique may vary as regards EUS duct access for rendezvous as opposed to a transenteric approach to stent placement. After endosonographic examination of the pancreas, the main pancreatic duct (MPD) is localized using an echoendoscope below the esophagogastric junction ( Fig. 1 ). To provide a larger area to target and enable antegrade passage of the guide wire, it is ideal to orient the echoendoscope parallel to the long axis of the MPD ( Fig. 2 ). The tip of the scope is positioned in either the stomach or the duodenal bulb, depending on which position provides the least distance between the gastrointestinal (GI) tract and the MPD, which technique is selected (retrograde or antegrade) ( Fig. 3 ) with the fewest vessels between the scope and the pancreatic duct, and the location with maximal scope stability.
Under both fluoroscopic and endosonographic guidance, the MPD is then punctured with either a 19- or 22-gauge FNA needle or the inner needle of a cystoenterostome. The stylet is removed. Pancreatic fluid is then aspirated to confirm location. Contrast is injected, mapping the pancreatic duct. Volume and concentration of contrast injection should be limited in an attempt to reduce the risk of inadvertent parenchyma or vascular injection and to help maintain visualization of targeted areas.
A guide wire is advanced through the FNA needle into the pancreatic duct ( Figs. 4 and 5 ). The needle is then removed, leaving the guide wire in place. If the goal is rendezvous access via a luminal endoscopic route and the wire can be passed through the stricture or anastomosis into the bowel lumen, no further tract dilation is necessary. If transenteric stent placement is planned, a bougie dilator (SBDC-7 or -6, Wilson Cook), a 4- or 6-mm balloon dilator (Boston Scientific) ( Figs. 6 and 7 ), or administration of electrocautery using a diathermic sheath is used to enlarge the newly created fistula.
Selection of Access Site (Choice of Approach)
Pancreaticogastrostomy is most frequently described in the current literature, likely attributable to accessibility to the pancreatic duct from the stomach, even in patients with surgically altered anatomy. Pancreaticoduodenostomy is a more recently described technique used by Tessier and colleagues, who prefer the transbulbar and retrograde approach because the “long” scope position allows a better view of the MPD and better stability during the procedure, and facilitates stent placement.
Selection of Drainage Route
Transpapillary pancreatic drainage (rendezvous and antegrade)
The preference is always to advance the guide wire in an antegrade fashion into the duodenum or the jejunum, whenever possible, in patients with surgically altered anatomy. A rendezvous procedure is possible when the endoscope can be advanced to the papillary orifice or the surgical anastomosis for retrieval of the guide wire looped into the small bowel.
ERP can then be performed using a standard duodenoscope. In patients with surgically altered anatomy, ERP is performed with a pediatric colonoscope or an enteroscope. Cannulation of the pancreatic duct can be achieved alongside the guide wire or by retrieving the guide wire into the working channel of the endoscope for subsequent therapeutic intervention. The wire is grasped with a snare or a biopsy forceps and is withdrawn into the working channel for retrograde introduction of a sphincterotome over the wire. Subsequently, conventional transpapillary drainage can be performed.
Antegrade or retrograde drainage
If rendezvous ERCP is not possible, 2 options exist: (1) stent placement across the papilla or anastomosis for “downstream” drainage, or (2) stent placement above the stricture and across the puncture tract for “upstream” drainage. Downstream drainage is typically preferred, though not always possible ( Figs. 8–10 ).
Related posts:
Advances in Pancreatic Endoscopy
Effective Endoscopic Management of Pancreatic Diseases
Role of Endoscopic Ultrasonography in the Diagnosis of Acute and Chronic Pancreatitis
Endoscopic Therapy for Acute Recurrent Pancreatitis
Endoscopic Therapy for Chronic Pancreatitis
ERCP for Biliary Strictures Associated with Chronic Pancreatitis
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