Training for Pseudocyst Management


29
Training for Pseudocyst Management


Todd H. Baron


University of North Carolina, Chapel Hill, NC, USA


Procedure(s) to be considered


The procedures to be considered for pseudocyst drainage include upper endoscopy using a side‐viewing endoscope, endoscopic retrograde cholangiopancreatography (ERCP), and endoscopic ultrasound (EUS). The procedures are used to obtain initial pseudocyst access and drainage, as well as to guide pancreatic duct interventions when necessary.


Prerequisite level of expertise and skill for learning this


Pseudocyst drainage is a technically challenging procedure. Performing endoscopists should have experience with ERCP techniques, and diagnostic and therapeutic EUS.


Special considerations


The necessary skills are best obtained in a high‐volume, tertiary referral center. The trainee must be trained by a trainer with particular expertise in pseudocyst access and drainage techniques, particularly EUS and ERCP with pancreatic duct stent placement. Training is supported by instruction in related disciplines as well.


Specific technical and cognitive skill sets


Pseudocyst management requires sufficient cognitive skills pertaining to clinical pancreatology, interpretation and use of noninvasive imaging (CT and magnetic resonance imaging [MRI]), and medical evaluation and follow‐up of pseudocysts to properly guide use and performance of therapeutic intervention. Necessary technical skills include therapeutic EUS and ERCP with stent placement, balloon dilation, and guidewire management. Baseline EUS skills include EUS‐guided fine needle aspiration (EUS‐FNA). The ability to manage procedure‐related adverse events is critical.


It is important to note first and foremost that there are several types of pancreatic fluid collections that are often confused with pancreatic pseudocysts on imaging studies. These include acute peripancreatic fluid collections, acute necrotic collections, walled‐off pancreatic necrosis (WOPN) [1], and chronic pseudocysts. This chapter addresses pancreatic pseudocysts but the methods used allow resolution of collections that are composed of liquid.


Acute peripancreatic fluid collections


Acute peripancreatic fluid collections arise early in the course of clinically mild (interstitial) acute pancreatitis and typically resolve without sequelae but may evolve into pancreatic pseudocysts. By definition, acute peripancreatic fluid collections are present within 4 weeks of onset of pancreatitis. They are liquefied and rarely require drainage.


Acute pancreatic pseudocyst


Acute pancreatic pseudocysts arise as a sequela of acute interstitial pancreatitis, require at least four weeks to form, and are devoid of significant solid debris. Acute pancreatic pseudocysts usually develop secondary to limited pancreatic necrosis that produces a pancreatic ductal leak (Figure 29.1). Despite the requirement of at least 4 weeks for a pseudocyst to form, it is important to note that this time period in and of itself does not define the collection as a pancreatic pseudocyst. In patients with significant pancreatic necrosis (≥30%), the early acute pancreatic and peripancreatic necrosis may resemble a pseudocyst radiographically, but instead represent WOPN. By definition, if these collections contain significant solid debris (i.e., necrosis), they are not pseudocysts and endoscopic treatment of these collections by typical pseudocyst drainage methods must be avoided due to the risk of infectious complications resulting from inadequate removal of solid debris [2].

Schematic illustration of the mechanism of formation of an acute pancreatic pseudocyst. Limited necrosis of the main pancreatic duct produces a ductal leak with accumulation of amylase-rich fluid.

Figure 29.1 Illustration of the mechanism of formation of an acute pancreatic pseudocyst. Limited necrosis of the main pancreatic duct produces a ductal leak with accumulation of amylase‐rich fluid.

Schematic illustration of the mechanism of formation of a chronic pancreatic pseudocyst. Obstruction of the main pancreatic duct by stones and/or stricture produces a duct blowout with accumulation of amylase-rich fluid.

Figure 29.2 Illustration of the mechanism of formation of a chronic pancreatic pseudocyst. Obstruction of the main pancreatic duct by stones and/or stricture produces a duct blowout with accumulation of amylase‐rich fluid.


Chronic pancreatic pseudocyst


Chronic pancreatic pseudocysts arise as a sequela of chronic pancreatitis and form secondary to stricture and/or stones that lead to main pancreatic duct obstruction. The resulting increased intraductal pressure leads to upstream ductal leak (Figure 29.2).


Acute necrotic collection (ANC)


ANC is a collection containing variable amounts of fluid and necrosis associated with necrotizing pancreatitis arising from the pancreatic parenchyma and/or peripancreatic tissues. It occurs only in the setting of necrotizing pancreatitis, within 4 weeks of onset and has no definable wall encapsulating the collection.


Walled‐off Pancreatic Necrosis (WOPN)


WOPN is a collection containing variable amounts of fluid and necrosis associated with necrotizing pancreatitis arising from the pancreatic parenchyma and/or peripancreatic tissues. It occurs only in the setting of necrotizing pancreatitis and requires at least 4 weeks after onset of acute pancreatitis to form. It has a well‐defined wall encapsulating the collection (Figure 29.3). The computed tomography (CT) appearance may mimic an acute pseudocyst (Figure 29.4). Because the underlying solid debris is frequently not discernible by CT, its homogeneous appearance may lead one to embark on standard pseudocyst drainage methods which do not adequately remove the underlying solid material. This may result in serious infectious complications. CT features that may distinguish WOPN from pancreatic pseudocysts include larger size, extension to paracolic space, irregular wall definition, presence of fat attenuation debris within the collection, and pancreatic deformity or discontinuity [3]. Data suggest that MRI accurately distinguishes WOPN from a pancreatic pseudocyst [4]. Since these collections are composed of liquid and solid material, they require more than pseudocyst drainage techniques to be successfully managed endoscopically.

Schematic illustration of illustration depicting organized pancreatic necrosis (walled-off necrosis). The collection is composed of liquid and solid and is an expansion of the area.

Figure 29.3 Illustration depicting organized pancreatic necrosis (walled‐off necrosis). The collection is composed of liquid and solid and is an expansion of the area.

Photo depicts CT of organized pancreatic necrosis. This collection occurred after an episode of severe pancreatitis and could be confused with a pseudocyst.

Figure 29.4 CT of organized pancreatic necrosis. This collection occurred after an episode of severe pancreatitis and could be confused with a pseudocyst.


Equipment


Essential equipment


Linear array echoendoscope and/or side‐viewing therapeutic endoscope (duodenoscope).


Access device (e.g., dedicated needles, needle knife, cystenterotome).


Dedicated luminal apposing metal stent (LAMS) with electrocautery‐enhanced delivery system.


Electrosurgical generator—blended and coagulation.


Water‐soluble contrast.


0.018”–0.035” guidewires (depending on needle used)


4, 6, 8, 10 mm dilating balloons.


7 and 10Fr double pigtail stents, array of lengths.


Array of straight pancreatic duct stents (5Fr, 7Fr, 10Fr diameters).


Fluoroscopy.


Salvage accessories:


Hemostasis accessories—injection needles, epinephrine, endoclips, bipolar electrocoagulation.


Rat‐toothed forceps—therapeutic size.


Standard polypectomy snare.


Key steps of proper technique


Pseudocyst drainage can be performed using a transmural (transgastric or transduodenal) and/or transpapillary approach. The transmural approach is now universally performed entirely under EUS guidance, with or without fluoroscopic guidance. These approaches will be discussed separately.


Prior to the procedure, there are several key aspects that must be considered.


Pre‐drainage evaluation


Before embarking upon endoscopic drainage of a pancreatic fluid collection, the endoscopist must always ask the following questions:



  1. Did the fluid collection arise secondary to pancreatic inflammation? There are many masqueraders of pancreatic pseudocysts, including: primary cystic pancreatic neoplasms (e.g., mucinous tumor or serous cystadenoma), extra‐pancreatic cystic lesions (e.g., duplication cyst, mesenteric cyst, or lymphoepithelial cyst), and other lesions including a pseudoaneurysm, abutting gallbladder, etc. The endoscopist should always consider the possibility of these other cystic lesions, particularly in patients without a well‐documented history of pancreatitis.
  2. Could the patient have an underlying pancreatic neoplasia such as a carcinoma or an islet cell tumor? An elderly patient who presents with either “idiopathic pancreatitis” complicated by a fluid collection or any patient with documented pancreatic pseudocyst in the absence of clinical pancreatitis should be carefully evaluated to exclude an underlying pancreatic neoplasm causing pancreatic ductal obstruction and upstream ductal leak. Similarly, autoimmune pancreatitis may lead to pseudocyst formation [5]. Solid pancreatic tumors may undergo necrosis and cystic degeneration and occasionally be mistaken for a pancreatic fluid collection.

Once the decision has been made to endoscopically manage a PFC, the following imaging and laboratory evaluation should be undertaken:

Only gold members can continue reading. Log In or Register to continue

Jul 31, 2022 | Posted by in GASTOINESTINAL SURGERY | Comments Off on Training for Pseudocyst Management
Premium Wordpress Themes by UFO Themes