Endoscopic Management of Pancreatic Fluid Collection

Abstract

Pancreatic fluid collections are known complication of pancreatitis. The revised Atlanta criteria classifies pancreatic fluid collections into four types: acute pancreatic fluid collections, acute necrotic collections, pancreatic pseudocyst and walled off necrosis. While most pancreatic fluid collection resolve on their own, interventions are required in the setting of symptoms and complications. The three common interventional approach in pancreatic fluid collection are: percutaneous, endoscopic and surgical, the latter may be by open or minimally invasive techniques. A hybrid approach can also be adopted. Each modality is associated with its own benefits and disadvantages.

Evolving technologies have revolutionized the treatment of pancreatic fluid collections with endoscopic approach having gained a prominence. Endoscopic drainage may be transmural or trans-sphincteric and aided with endoscopic ultrasound or endoscopic retrograde cholangiopancreatography. The availability of lumen apposing metal stents has emerged as a newer weapon in the already existing armamentarium as it can also facilitate necrosectomy in an infected “walled of necrosis”. Multidisciplinary approach is paramount to a successful management. This chapter highlights the concepts and techniques related to endoscopic drainage of pancreatic fluid collections.

Introduction

Pancreatic fluid collections (PFCs) are an important sequela of acute pancreatitis and if not managed appropriately can result in significant mobidity. The three main approaches adopted for drainage of PFCs are: percutaneously, surgically or endoscopically. The latter can be performed either with endoscopic ultrasound (EUS) guided cysto-gastrostomy and/or through endoscopic retrograde pancreaticography (ERCP) and transpapillary drainage. The first report of endoscopic drainage of PFC’s dates back to 1973 [1]. Recent advances in technology and technique has revolutionized the treatment of PFCs. Here we highlight the concepts and technique of endoscopic management of PFCs.

Classification and Natural History of PFC’S

Pancreatitis may be of two common types: interstitial edematous pancreatitis (IEP) and necrotizing pancreatitis (NP). Further the necrosis may be pancreatic or peripancreatic. The severity of pancreatitis is classified according to presence or absence of local or systemic complications (i.e. persistent organ failure >48 h) into mild moderate or severe. Local complications may be classified as early or late and necrotic or non-necrotic. Pancreatic fluid collections (local complications) are of four sub types as per the revised Atlanta classification [2]:

• 1. Acute pancreatic fluid collections (APFC):

  ≤4 weeks duration, non-necrotic collection, sequelae of IEP

• 2. Acute necrotic collections (ANC)

  ≤4 weeks duration, necrotic collection, sequelae of NP

• 3. Pancreatic Pseudocyst (PPC)

  >4 weeks duration, non-necrotic collection, sequelae of IEP

• 4. Walled off necrosis (WON)

  >4 weeks duration, necrotic collection, sequelae of NP

APFC normally develops after an episode of IEP and progresses to PPC if not resolved in 4 weeks whereas, ANC develops after acute necrotizing pancreatitis and if unresolved develops into WON. CECT further helps to classify the various pancreatic fluid collection. Pseudocysts have clear contents and a defined wall whereas WON have walled off variable amount of solid necrotic debris. Cross-sectional imaging after the first week can differentiate ANC and acute PFC. PFC have clear contents whereas ANC appears loculated with variable amount of debris within the fluid [2].

Evolving Concepts in Management

Acute collections (APFC or ANC) usually do not require any intervention as they improve with conservative management [3]. However, a proportion of symptomatic WON and pseudocysts require intervention. The various drainage options of PFCs are: (1) percutaneous drainage (2) endoscopic drainage/stenting (3) surgical drainage, which may be open or by minimally invasive approaches. With advent of technical innovations in interventional endoscopy, invasive surgical procedures can be avoided in majority of PFC patients.

Certain newer insights have come to picture, namely

• (a) Outcome of a drainage procedure is better if performed once the collection gets walled off or encapsulated (>4 week).

• (b) Minimally invasive approach to the management of PFCs is better than the conventional open surgical methods

• (c) The outcome of endoscopic drainage depends on the nature of PFC i.e. pseudocyst or WON [4,5,6,7].

Symptomatic PFC’s are initially managed by intravenous fluid, antibiotics and nutritional support and later if symptoms persist by minimally invasive endoscopic, percutaneous or surgical (Laparoscopic) drainage ± necrosectomy (Endoscopic or surgical) which depends on presence of symptomatic necrosis and possible blockade of the newly created passage.

Minimally Invasive Approach

Minimally invasive approach to the management of PFCs (especially WON) has gained impetus after a recent landmark trial the Dutch “PANTER” trial. The trial advocated a “step-up approach” i.e., attempts of initial per-cutaneous or endoscopic transgastric drainage of infected pancreatic necrotic collection followed by minimally invasive retroperitoneal necrosectomy if unresolved and has observed less major complications and mortality with the approach as opposed to the open necrosectomy [5]. Necrosectomy performed by minimally invasive approach reduces pro-inflammatory response as well as new onset organ failure by decreasing surgical trauma as compared to open surgical necrosectomy [5]. The results of the trial has led to a worldwide acceptance of the step up approach and minimally invasive necrosectomy as treatment options for PFC’s.

Specific Technology

Planning of Intervention in PFCs

Indications: Asymptomatic PFCs do not require treatment as they often spontaneously resolve. The former criteria of drainage namely “the rule of 6” i.e. >6 cm size, >6 mm wall thickness and >6 weeks duration are no longer deemed valid.

The current indications for intervention for PFCs are presence of:

• Symptoms: (abdominal pain, biliary, gastric outlet or intestinal obstruction)

• Complications: (infection, rupture, haemorrhage)

• Rapid enlargement: (enlarging at a rapid rate to a large size)

Pre Procedure Investigations

It is prudent to rule out other causes of pancreatic cysts such as cystic neoplasm, duplication cyst, as also complications like presence of pseudoaneurysm before intervention. Evaluation of pancreatic duct integrity is also helpful to rule out DPDS (disconnected pancreatic duct syndrome), which is associated with WON and communication of pseudocyst with the duct. The following investigations can aid in assessment:

• Contrast enhanced computed tomography (CECT),

• Magnetic Resonance Imaging (MRI)

• Magnetic resonance cholangio pancreatography (MRCP)

• Endoscopic Ultrasound (EUS).

• ERCP Endoscopic retrograde cholangiopancreaticography

Percutaneous Catheter Drainage and Necrosectomy

Image (CT/USG) guided percutaneous intervention such as aspiration or placement of an external drainage catheter provides an alternative when the fluid collection is infected and cyst walls are immature where laparoscopic or endoscopic approach may not be feasible or as a primary procedure in step-up approach. It can also be considered in salvage therapy of residual or infected collections.

A self-retaining catheter of 12–30 Fr size is preferred. The retroperitoneal route avoids peritoneal contamination and minimizes chances of bowel injury and is therefore preferred. Irrigation through catheter may also be beneficial. An initial catheter drainage is helpful to control sepsis. If complete resolution does not occur with simple catheter drainage techniques of retroperitoneal necrosectomy such as VARD (video assisted retroperitoneal drainage) or percutaneous endoscopic necrosectomy may be helpful.

However, complications may be associated with percutaneous catheter drainage such as secondary infections related to the catheter,

• occlusion of catheter,

• peri catheter cellulitis,

• sepsis and prolonged pancreatic fistula in presence of cysto-ductal communication.

When percutaneous drainage is compared with endoscopic approach, endoscopic approach is shown to have higher rates of treatment success with low rates of need for second intervention/procedure and less number of days of hospital admission. Therefore, this method of percutaneous drainage should be reserved for a selective group of patients who have one of the following [5]:

• 1. Immature collections which are infected particularly in a moribund patient

• 2. Development of PFC after resection of pancreatic tail

• 3. Anatomical variants

• 4. Any contraindication for endoscopic therapy.

Endoscopic Drainage of PPC

Pancreatic pseudocyst have been traditionally drained surgically (open or laparoscopic approach) [8]. However high complication (upto 30%) and recurrence rates have been noted [9]. Endoscopic drainage merits being a less-invasive and more cost-effective option [9, 10]. An endoscopic approach should be attempted with preferable support of interventional radiology and surgical team in the event of complications during the procedure and is now emerging as the preferred first line approach [9].

Various Endoscopic Approaches in PFC’s

Methods described for endoscopic drainage are as follows:

• Transmural—Esophagogastroduodenoscopy (EGD) based or EUS guided.

• Transpapillary—Under ERCP guidance.

• Combined/Hybrid approaches

  • Dual transmural and transpapillary route

  • Dual endoscopic and percutaneous drainage

Factors that Influence the Route of Endoscopic Drainage

• 1. Anatomic proximity of the PFC to the stomach and duodenum. This is an important factor which helps in decision making regarding the choice of lumen for drainage. If the collection is near the stomach and is producing a visible intramural bulge on the gastric wall (Fig. 1), it is amenable to drainage via EGD alone method described in details later in this chapter. EUS is recommended if the PFC is not bulging (Fig. 2) or is slightly away from the lumen wall.

• 2. Anatomy of the pancreatic duct with cystoductal communication (CDC) is another factor. If the collection is communicating with main pancreatic duct trans-papillary drainage is possible via ERCP.

• 3. Size of the collection with presence of necrosis in the cyst, helps in decision making as collection with large necrotic content compared to fluid component are not amenable to simple drainage procedures. Presence of necrosis might require multiple attempts for total clearance.

• 4. Number of cysts and internal communication between them is an important factor while making decisions as communicating cysts are better amenable to endoscopic procedures compared to non-communicating ones.

• 5. Thickness of cysts wall: Cyst wall must be mature before attempting any kind of drainage procedure so pre procedure radiological evaluation is mandatory prior to venturing into any kind of drainage procedure.

Fig. 1

Large pseudocyst (PPC) bulging into stomach (Yellow Arrow) [Image courtesy: Dr Deborshi Sharma]

Fig. 2

Large pseudocyst (PPC) with ≥1 cm gap (Yellow arrow) between stomach (S) and cyst (PPC) [Image Courtesy: Dr Deborshi Sharma]

Endoscopic Transmural Drainage of PFC

The main principle of endoscopic transmural drainage is to create an adequate drainage portal which is accessible for repeated interventions and is associated with minimal complications [9].

Preprocedure Preparation

• Bleeding/Coagulation disorders needs to be corrected

• Preprocedural antibiotics reduce risk of infective complications particularly for WON

• Procedure is usually performed under sedation with analgesia but can also be undertaken in general anaesthesia.

• Backup interventional radiology/surgical support should be arranged.

Esophago Gastro Duodenoscopy (EGD) Based PFC Drainage

Transmural drainage technique: The technique incorporates a standard sequence of steps as follows:

• identification of the ideal puncture site under endoscopic guidance over the bulge,

• needle puncture at the site and through the PPC wall into the cyst and diagnostic aspiration to look for haemorrhage or infection. The aspirated fluid should be sent for microbiological analysis.

• insertion of guide wire through the needle

• coiling of guidewire inside the cyst cavity (can be confirmed with fluoroscopy)

• removal of needle

• dilatation of cystogastric tract using cystotome and balloon over guide wire causes cyst fluid to gush into the stomach

• placement of stents (commonly double pigtail stents) communicating the cyst to the stomach cavity (Figs. 3 and 4).

Fig. 3

(a) Needle knife papillotome making incision at the bulging site, (b) Balloon dilatation of the tract, (c) Fluoroscopy picture of guide wire in situ, (d) Double pigtail stent draining from the cyst into stomach

Fig. 4

Schematic illustration of endoscopic transmural drainage

Plastic or metal stents are put to accomplish endoscopic drainage of PFC’s. Whereas plastic stent alone may suffice in pseudocysts with only fluid content, fully covered self-expanding metal stents or LAMS (lumen apposing covered self-expanding metallic stents) may be preferable for WON to drain necrotic solid component. EGD only based approach has been associated with certain disadvantage like it requires an endoluminal bulge of the cyst (Fig. 1) for it to be successfully performed and since it is a blind procedure high risk of bleeding is present from intervening vessels or collaterals.

EUS Guided Transmural PFC Drainage (Fig. 5)

Benefits: The EUS guided transmural PFC drainage technique is similar to only EGD guided technique with added perceived benefits as follows:

• helpful in non-bulging PFCs where endoscopic definable compression is absent.

• can be utilized to assess contents of the cyst for presence of necrotic material, which can influence the choice of stents and drainage maneuvers (necrosectomy or multiple stents may be desirable in WON).

• can identify associated pathology in pancreatic gland i.e. status of pancreatic duct, stones, as also detect masquerading cysts/pancreatic tumors

• helps identify the route and site of drainage viz. transgastric versus trans duodenal drainage. The lumen which is in close proximity to the PFC is selected, which ideally should be <1 cm from the cyst wall, with no intervening vital structures between the cyst and lumen wall to reduce risk of injury or perforation

• helpful in PFCs in unusual locations (for example trans esophageal roue) [9].

• addition of doppler identifies interceding vessels, collaterals/varices or pseudoaneurysms (resultant due to portal hypertension secondary to portal vein or splenic vein thrombosis) in close proximity to the identified tract of drainage/catheter placement which have the potential to bleed during the procedure.

• can determine adequacy of guidewire and stent placement into the cyst cavity in addition to fluoroscopy

• help detect post transmural puncture intracystic haemorrhage.

Fig. 5

EUS aided transmural drainage of PFC. (a) EUS image of pancreatic fluid collection, (b) EUS guided dilatation of tract (Green arrow), (c) Placement of Lumen apposing metal stent (LAMS), (d) LAMS in position draining fluid (Guide wire is also seen)

Use of “Forward viewing endoscope”: Traditionally an oblique viewing endoscope was used for EUS guided procedure which permitted puncture only at an angulation. Recently a forward viewing endoscope has been utilized for drainage of pancreatic pseudocyst which enables direct perpendicular puncture of PFCs and is stated to yield better results [9, 11,12,13,14].

Use of multiple stents: Particularly for the drainage of WON, multiple stents or catheters may be needed. Use of additional nasocystic catheter can assist in irrigation and flushing out of necrotic debris from the cavity which can obviate the need for necrosectomy in some cases. Necrotic debris in the cyst cavity can be flushed with normal saline solution (100 mL every 4 h until the aspirate is clear) [9]. Techniques have evolved for insertion of multiple catheters using a single puncture more commonly known as “one step double wire technique” [15, 16].

Pre procedure ERCP: Preprocedure ERCP has been used by some authors to delineate ductal disruptions and perform a sphincterotomy or stenting before drainage (as discussed below).

Brief Outline of the Standard Steps of the EUS Guided Transmural Drainage

• Identification of optimal site by EUS (site of PFC <1 cm from posterior gastric/ medial duodenal wall with no interceding vascular abnormalities or viscera). Rarely distal esophagus has been described as portal of drainage.

• Puncture of PFC and diagnostic aspiration of fluid content is performed with a 19-gauge needle under real time EUS guidance (to exclude any misdiagnosis and to look for infection and hemorrhage within the cyst).

• Under simultaneous EUS and fluoroscopic guidance a guidewire (0.035-inch × 440 cm) is inserted through the needle into PFC cavity with sufficient length for looping it in the cavity. More than one guidewire may be placed if multiple stents are to be used.

• Needle is removed after placement of guidewires

• Enlargement of the tract by sequential dilatation of the tract done with 6–10 mm hydrostatic balloon dilator and/or cystotome to facilitate insertion of multiple plastic stent (gush of cyst fluid occurs into the stomach following dilatation)

• Insertion of double-pigtail plastic stents (sizes between 7 and 10 Fr) under EUS and fluoroscopic guidance. The double pigtail is designed to make it self-retaining and prevention of migration into the cyst or bowel lumen.

• Most frequently two plastic double-pigtailed biliary stents are placed. Multiple stents or a nasocystic catheter is deployed if indicated.

• In uncomplicated cases, number and size of plastic stent used or number of interventions done, does not affect outcome

• To evaluate response to intervention a repeat CT scan is done after 4–6 weeks [9].

Complications and Outcome

Some of the reported complications of endoscopic transmural drainage of PFCs are:

• bleeding

• perforation of viscera

• pneumoperitoneum

• fistula formation

• stent related problems (migration/occlusion) [17, 18].

Use of electrocautery along with knife cystotome has been tried to reduce bleeding complications [18]. In a prospective randomized trial comparing only EGD based (Blind Technique) and EUS-based approach in cysts >4 cm size, equivalent results were noted [17]. It needs to be emphasized that whereas bulging PFCs are drained with EGD only non-bulging PFCs are drained with combined EGD and EUS technique which can confound comparisons [18]. Another prospective randomized trial noted a higher technical success rate and lower complications with EUS guided EGD when compared to EGD alone technique [19]. EUS should be preferred as a first-line of treatment in all, particularly in nonbulging cysts [17,18,19].

Transpapillary Drainage of PFC (Fig. 6)

Need of Pre Drainage ERCP (Pancreatogram)

Before the advent of advanced imaging systems for the pancreatic duct like MRCP, an ERCP-based algorithm was advocated to guide treatment of PFCs based on pancreatic duct morphology viz. ductal disruption, strictures, complete cutoff of the duct and cystoductal communication (CDC) necessitating the need for pre procedure ERCP [20, 21]. However, due to availability of noninvasive imaging like MRCP, pre drainage ERCP pancreatogram is now not regularly used to guide the drainage approach.

Fig. 6

Schematic illustration of transpapillary stenting

Transpapillary Drainage (ERCP Guided)

PFCs communicating with the main pancreatic duct can be managed with transpapillary stenting of the main pancreatic duct through the main or minor papilla which may be accompanied with a sphincterotomy. Alternatively, drainage of the PFCs through the transpapillary stent (cystopancreatic stents) has been advocated. Thus, the stent may be placed into the collection or positioned close to the collection in a manner to bridge the duct disruption/stricture, by coursing into the pancreatic tail [22,23,24]. Insertion of a transpapillary nasocystic catheter can be used for irrigation of the cyst cavity [22]. Even a simple stenting can improve flow dynamics of the pancreatic duct by promoting flow of pancreatic secretions through the papilla (a low resistance tract) rather than into the PFCs (a relatively high resistance tract). Complete bridging of the disruption is preferable particularly in pancreatic body and tail disruptions [25].

Disadvantages of Transpapillary Approach

• stents need to be routinely exchanged every 6–8 weeks

• a prolonged duration of treatment may be needed at times for 3–6 months [9, 23, 24].

• ERCP induced pancreatitis

• Scarring of main pancreatic duct due to stent

• Infection of the collection

• Inability to adequately drain large collections (transmural approach is preferred for large collections) [25].

Advantages of Transpapillary approach: The potential benefits of transpapillary approach over transmural procedure are:

• decreased risk of bleeding, particularly useful in context of gastric varices and portal hypertension where a transmural procedure carries high risk of bleeding

• lower chances of perforation

• concomitant pancreatic gland pathology can be addressed viz. pancreatic duct stones and strictures [25].

Contraindications to transpapillary stenting:

• completely intact PD

• completely disrupted/disconnected pancreatic duct syndrome with no communication between the downstream PD and PPC [9].

Transpapillary nasocystic catheter insertion: If necrotic debris are present within the cyst cavity, a transpapillary nasocystic catheter can be inserted to facilitate aspiration of PPC/WON contents by repeatedly flushing the cyst cavity with saline (a type of indirect necrosectomy) which also aids in faster liquefaction of the cyst contents [22].

Combined Approach for Drainage of PFCs

Combined endoscopic transmural and transpapillary approach: Addition of a transpapillary stenting to a transmural drainage may be particularly beneficial for partial duct disruptions, but its role in complete duct disruptions is not as encouraging [26].

Dual endoscopic and percutaneous technique: A combined endoscopic drainage along with radiological percutaneous drainage was investigated and found to be beneficial for treatment of WON. It alleviated the need for surgical necrosectomy and had lower incidence of percutaneous fistula [25].

Multiple transluminal gateway technique: It involves creation of multiple transmural drainage tracts, one of which is used for nasocystic irrigation which leads to higher clinical success rate [25].

Choice of Stents, Plastic Versus Metallic Stents

Plastic or metallic stents can be used for drainage.

Advantages of plastic stent:

• Less likely to erode into adjacent structures

• Can be left in situ for longer time

Disadvantages of plastic stents/double pigtail stents (DPS):

• Stent migration

• Plastic stents have narrow lumen necessitating placement of multiple stents which is labor intensive and time consuming

• Due to their small luminal diameter, they are prone to occlusion

• Larger plastic stents are difficult to deploy through small calibre channels of the endoscope [27].

• Stent end abutting against luminal wall can lead to incomplete drainage.

• If apposition of cyst wall and GI lumen walls is lacking plastic stents can cause fluid leakage in the intervening space.

SEMS (Self-Expanding Metal Stents) and LAMS (Lumen Apposing Metal Stents)

SEMS: Fully covered SEMS which are commonly used to stent gastrointestinal strictures were initially tested in drainage of PFCs to overcome the shortcomings of DPS [27]. The main advantage of fully covered SEMS is having a larger diameter than DPS and only a single stent is needed instead of multiple stents. However fully covered SEMS still has potential risk of migration and modification with fins or placement of DPS across the fully covered SEMS has been suggested to prevent overt migration [28]. SEMS has not been beneficial over DPS for PPC but may be more useful in WON [28].

LAMS: LAMS (AXIOS; Xlumena Mountain View CA, approved in USA & NAGI; approved in Europe) are saddle-shaped, nitinol, braided, flexible stents fully covered with a silicon membrane designed to overcome the drawbacks of DPS and SEMS. The stent has bilateral double-walled anchoring barbell flanges designed to hold the stomach or duodenal wall in direct opposition to the PFC wall, reducing the risk of migration. This stent is available in 10 and 15 mm size diameters and measures 10 mm in length. A 15-mm diameter allows for the passage of conventional upper GI endoscope for reinterventions such as repeated debridement, irrigation or necrosectomy [9].

Endoscopic Management of WON and Endoscopic Necrosectomy (Figs. 7, 8, and 9)

Management of WON differs from PPC as the former requires debridement, often multiple interventions, which may be:

• indirect i.e. irrigation and catheter drainage technique (implemented as a step up procedure)

• direct endoscopic necrosectomy.

Fig. 7

Necrotic debris seen through the LAMS stent

Fig. 8

Necrotic debris in cavity seen on an endoscope passed through the stent

Fig. 9

Cavity with necrotic debris and mucopurulent fluid irrigating fluid

The various endoscopic approaches described in the treatment of WON are:

• Endoscopic single or multiple stent transmural drainage with nasocystic irrigation

• Endoscopic transmural drainage with PEG/PEJ irrigation

• Endoscopic transmural drainage with percutaneous irrigation

• Endoscopic transmural drainage with direct endoscopic necrosectomy

• Percutaneous endoscopic drainage and necrosectomy

  [29].

Open necrosectomy for pancreatic necrosis is reported to have very high morbidity (34%–95%), and mortality ranging from 6% to 25% [30]. It also causes long-term complications like pancreatic exocrine insufficiency. Novel endoscopic approaches have revolutionized the treatment of infected pancreatic necrosis [29,30,31,32]. Nevertheless, risk of serious complications exist and it is important to address issues of pancreatic ductal pathology (disruptions/stricture/stones) to minimize recurrence [32].

Indications and Factors Deciding the Timing of Necrosectomy

• Sterile acute pancreatic necrosis does not require intervention neither early nor delayed unless symptomatic

• Infected early pancreatic necrosis seldom require early intervention and it is prudent to delay interventions by 4–6 weeks.

• If it is necessary to intervene in early pancreatic necrosis because of clinical deterioration with signs of sepsis, radiological or endoscopic approach should be preferred over surgery

• Only symptomatic WON with discrete encapsulation should undergo intervention after 4–6 weeks

• Asymptomatic WON irrespective of size and duration does not require intervention [30].

Direct Endoscopic Necrosectomy (DEN)

The procedure is performed under general anaesthesia with C02 insufflation. The initial steps of Direct Endoscopic Necrosectomy (DEN) is similar to EUS guided endoscopic transmural drainage but involves dilatation of the cysto-gastric tract with a balloon of larger size upto 20 mm and placement of LAMS which can allow subsequent multiple sessions of DEN without need for repeated dilatation. After the initial establishment of cystogastric tract, the echoendoscope is replaced with a larger single channel or double channel endoscope which is advanced into the cavity of WON for direct necrosectomy. The cavity is lavaged with normal saline and necrotic debris is removed under direct vision using forceps, snares or baskets (Fig. 9) [33]. Diluted Hydrogen peroxide irrigation can also be used to help in loosening up of necrotic tissue. Newer stents have wider lumen which allow multiple sessions of DEN without need for repeated dilatations. Multiple sessions may be required for completing the procedure which is regarded as a distinct disadvantage of the DEN procedure.

Waterjet necrosectomy device (WAND): Previously there was no device designed exactly for endoscopic necrosectomy and retrieval of necrotic material was done with all available snares, forceps or baskets which appeared to be suboptimal. Bulky or adherent necrotic slough may pose difficulty during removal A recent innovation is the waterjet necrosectomy device (WAND) which has been tested in preclinical series (Fig. 10). It can be introduced through a 2.8-mm working channel of a standard adult upper GI endoscope. (Fig. 11) The principle of WAND is necrosectomy by irrigation with water under controlled pressure rather than mechanical debridement. WAND is designed to provide irrigation pressures which are capable of fragmenting nonviable necrotic tissue, and at same time avoiding injury to healthy tissue [34].

Fig. 10

Waterjet necrosectomy device (WAND) (Image courtesy Dr. Patrick Stephen Yachimski, Nashville, TN, USA. Published with his permission)

Fig. 11

(a): WANDPTFE catheter fitted through the working channel of an UGI Endoscope. (b): Waterjet noozle & Handle body (Image courtesy Dr Patrick Stephen Yachimski, Nashville, TN, USA. Published with his permission)

Complications

DEN is associated with significant complications and should not be performed unless indicated despite the high quoted clinical success rate (75–91%). A high morbidity (14–33%) has been reported with mortality in up to 11% patients. Bleeding and perforation are the commonly reported complications. Air embolism been described with DEN, which can be circumvented by using CO2 for insufflation during the procedure [35,36,37,38].

Complications are higher with WON as compared to PPC [39].

Factors directly influencing success rates after endoscopic intervention or drainage of PPC/WON are:

• 1. Endoscopic vs EUS guided drainage.

• 2. Nature of collections (PPC or WON)

• 3. Direct Endoscopic Necrosectomy performed or not.

• 4. Type of stent used (Plastic vs Metal).

Conclusion

The management of PFCs has evolved from primarily open surgical drainage to endoscopic/radiological based minimally invasive approach. Only symptomatic PFCs need intervention preferably after 4 weeks. Endoscopic procedures with endoprosthesis insertion can manage most PFCs that require intervention. EUS guidance whenever available should be used with endoscopic procedures to decrease complications. Whereas PPC often resolve with drainage procedures like endoscopic transmural drainage or endoscopic transpapillary drainage, necrosectomy may be necessary in addition to drainage in WON a complication of necrotizing pancreatitis. Lately patients with WON have safely undergone endoscopic necrosectomy, obviating the need for surgical exploration. If PD disruption is suspected, ERCP with PD stenting should be done to prevent recurrence of PFCs after drainage. An individualized patient centric team approach comprising of gastroenterologist, endoscopists, interventional radiologists, intensivists and the surgeon is desirable.

Key Clinical Points

• 1. PFCs are classified based on duration and type of collection i.e. necrotic versus clear into APFC, ANC, PPC and WON.

• 2. Intervention for drainage is usually not required in APFC and ANC as they often improve with conservative management.

• 3. Only a proportion of symptomatic Walled of Necrosis (WON) and Pseudocysts (PPC) require intervention.

• 4. Asymptomatic PFCs do not require interventions irrespective of size and duration

• 5. Interventions in symptomatic PFCs are best delayed until after 4 weeks unless there are compelling evidence for early intervention like sepsis

• 6. PFCs can be drained surgically, percutaneously under radiologic guidance or endoscopically

• 7. Minimally invasive approaches have less morbidity than open surgical procedures for drainage of PFCs

• 8. Pre procedure radiological investigations, CT scan, MRI, MRCP can provide information regarding the maturity of cyst wall, necrosis, location i.e. proximity to bowel, complications like pseudoaneurysm and status of the pancreatic duct which are important determinants of the route and mode of intervention

• 9. Anatomic relationship of the PFC to the stomach and duodenum (distance from gastric or duodenal wall) helps in decision making regarding the choice of lumen for drainage

• 10. Endoscopic drainage of PFCs can be done either transmurally or through transpapillary route with or without EUS

• 11. Only EGD based transmural approach requires presence of a luminal compression visible as endoluminal bulge of the cyst during endoscopy

• 12. In non-bulging PFCs EUS along with EGD is required for transmural drainage

• 13. Transpapillary approach has decreased risk of bleeding or perforation compared to transmural drainage.

• 14. Added advantage of transpapillary approach is that concomitant ductal pathology can be addressed viz. intraductal pancreatic stones and pancreatic duct strictures, ductal disruptions, thus promoting early cyst resolution and decreasing recurrence

• 15. Endoscopic drainage of the cyst can be achieved with plastic DPS or metallic fully covered SEMS/ LAMS.

• 16. WON may require necrosectomy along with drainage

• 17. Necrosectomy can be performed as a step up procedure with repeated irrigation and drainage or direct endoscopic necrosectomy

• 18. Direct Endoscopic Necrosectomy (DEN) involves advancement of the endoscope into the cavity of WON through the tract and removal of necrotic material through, snares, baskets and forceps

• 19. A large, 15 mm, LAMS can facilitate passage of conventional upper GI endoscope into the cyst to enable necrosectomy

• 20. DEN has significant complications therefore it should not be performed unless indicated and should be done by experts

• 21. Waterjet necrosectomy device (WAND) is a recent innovative aid devised for necrosectomy which has been evaluated in preclinical studies and may prove promising in future.

Editor’s Note

References: Main chapter references are included after the “References Editor’s Note” section.

The three common approaches in management of peripancreatic fluid collections are:

• 1. Percutaneous drainage

• 2. Endoscopic drainage

• 3. Surgical drainage (laparoscopic/open).

In a recently published meta-analysis on the three approaches the endoscopic and surgical drainage were found to be better as regards success rates than percutaneous drainage. Moreover, the endoscopic drainage group enjoyed the added benefits of a shorter hospital stay [1].

Endoscopic Versus Percutaneous Drainage

Meta-analysis comparing endoscopic and percutaneous drainage noted a trend for higher success rate, lower reintervention and need for open drainage as also reduced hospital stay in the endoscopic group [2, 3] (Table EN1).

Table EN1 Endoscopic versus percutaneous drainage of pancreatic fluid collection

Laparoscopic Versus Endoscopic Drainage

PPC: A randomized controlled trial comparing endoscopic and laparoscopic drainage of pancreatic fluid collections noted equivalent outcome with a trend for higher success rates after laparoscopic group though the difference was not statistically significant; 83.3% in the laparoscopic and 76.6% in the endoscopic group (p = 0.7) after the index intervention and 93.3% and 90% in the laparoscopic and endoscopic groups respectively (p = 1.0) [4].

WON: Table EN2, summarizes the results of meta-analysis of endoscopic versus surgical necrosectomy for walled off pancreatic necrosis particularly minimally invasive surgical necrosectomy. Most studies observed a higher incidence of complications such as multiorgan failure, pancreatic and enterocutaneous fistulae in surgical as opposed to endoscopic group. A lower length of hospital stay was also noted in the endoscopic group but the endoscopic group required a higher number of interventions increasing the cost [5–8].

Table EN2 Meta-analyses comparing endoscopic versus surgical/minimally invasive method of treatment in pancreatic necrosectomy

Transphincteric Stenting in Transmural Drainage

The other contentious issue in endoscopic drainage is need for transsphincteric stenting in transmural drainage and also the choice of stents metallic versus plastic. No advantage was observed of transpapillary stenting for patients who undergo transmural drainage of pseudocysts in a recent metaanalysis [9].

Plastic Versus Metallic Stents

Table EN3 enumerates various meta-analyses published on use of metallic versus plastic stents [10–16]. Most studies conclude that metallic stents are preferable over plastic stents as they have a higher clinical success rate and lower adverse event. The commonly reported adverse events being stent migration, bleeding, perforation, infection and stent occlusion. However metallic stents may erode into an adjacent vasculature.

Table EN3 Meta-analyses on use of metallic versus plastic stent for drainage of pancreatic fluid collection

References for Editor’s notes

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