**2.1 Endoscopic drainage of PFCs**

Characterization of PFCs into pseudocysts and WON is important prior to ETD. WON has variable amount of necrotic debris and therefore, has a protracted course and more frequent requirement of re-interventions as compared to pseudocysts (**Figures 2** and **3**). Computed tomography is frequently used to localize the site of collection. However, it may not accurately differentiate between the solid and liquid contents of the collection (**Figures 4** and **5**). Magnetic resonance imaging (MRI)

#### **Figure 4.** *CT image in a case of pancreatic pseudocyst. Note the well-defined boundary and clear contents of the cyst.*

#### **Figure 5.**

*CT image in a case of walled off necrosis replacing almost entire pancreas. Note that the necrotic contents of the cyst cavity are not obvious in CT image.*

and endoscopic ultrasound (EUS) are better imaging modalities for qualitative assessment of PFCs. We perform both CECT and EUS to define the anatomical relation of PFCs to the lumen and characterize them into pseudocyst or WON, respectively.

The technique of endoscopic drainage of PFCs involves the following steps: puncture of the cysto-gastric or cysto-duodenal wall using a 19 gauge needle and aspiration of cyst contents, coiling of guidewire within the cyst cavity under fluoroscopy guidance, dilatation of the tract using cystotome and balloon and deployment of plastic or metal endoprostheses. EUS guided drainage is preferred to endoscopic approach as intervening vessels can be avoided and non-bulging collections can be targeted under vision [10].

The success rate of ETD with or without endoscopic necrosectomy ranges from 80 to 95% in recent studies [11–19] (**Table 1**). The outcomes of ETD of PFCs is variable in literature presumably due to heterogeneity in the nature of collection, that is, pseudocyst or WON, type of stent used, and whether necrosectomy is performed or not [20]. In addition, the presence of disconnected pancreatic duct (DPD) may impact the outcomes of ETD. The requirement of hybrid treatment, re-interventions, recurrences, and rescue surgery appear to be higher in the patients with DPD [21].

ETD of PFCs is safe, and major complications are uncommon. Complications related to ETD occur in 10–40% of patients with WON [22]. Supra-infection of the cyst cavity is the most common significant complication associated with ETD. Occlusion of the stent with necrotic debris and inadequate drainage may lead to sepsis. In such situations, de-clogging of the metal stent, cyst lavage with saline or diluted hydrogen peroxide and direct endoscopic necrosectomy (DEN) are often helpful. Other complications associated with ETD include bleeding and perforation. Recent studies have drawn attention towards the relatively high incidence of bleeding especially with the use of large caliber metal stents (LCMS) [23–25]. Since, majority of the bleeding episodes occurred ≥3 weeks after the deployment of LCMS, the current trend is to remove LCMS between 2 and 3 weeks in cases of resolution of PFC [24].

#### **2.2 Endoscopic transmural drainage: choice of stents**

Endoscopic drainage of PFCs can be performed using pigtail plastic stents or metal stents. Plastic stents have been effectively used for the drainage of PFCs for

**11**

**N**

Walter et al. [11]

Siddiqui et al. [12]

Sharaiha et al. [13]

Lakhtakia et al. [14]

Venkatachalapathy

116

PC 46

WON 70

et al. [15]

Dhir et al. [16] Yang et al. [17]

Kumta et al. [18]

Teoh et al. [19]

**Table 1.**

*Outcome of endoscopic transmural drainage in pancreatic fluid collections using large caliber metal stents.*

59

PC 20

LAMS

100%

3.4%

None

(SPAXUS)

*PFC, pancreatic fluid collection; PC, pseudocyst; WON, walled off necrosis; Sx, surgery; PCD, percutaneous drainage; NR, not reported; LAMS, lumen apposing metal stent.*

WON 39

192

PC 41

WON 151

122

PC 58

LAMS

96.5%

NR

Sx: 3.3% WON

62.3%

92.6%

3.7%

7.3%/3.1%

(AXIOS)

LAMS (AXIOS)

WON 64

88

All WON

Biflanged

80.7%

9.1%

Sx 1.1%

(Nagi)

205

All WON

Biflanged

96.5%

2.4%

1%/1%

(Nagi)

LAMS

94%

0.86%

2.5%/−

(AXIOS)

124

All WON

LAMS

86.3%

4.8%

10.5%/2.4%

(AXIOS)

82

PC 12

WON 68

61

PC 15

WON 46

**PFC**

**Type of stent**

LAMS

(AXIOS)

LAMS

(AXIOS)

**Success**

93%

81%

100%

1.2%

PCD 5%

88.2%

**Recurrence**

NR

**Adjuvant PCD or Sx**

Sx 6.5%

**Complications**

Infection 6.5%

Perforation 1.6%

Stent mal-deployment

2.5%

Bleeding 7.5%

Infection 3.2%

Stent occlusion 4%

Stent migration 2.4%

Bleeding 1.4%

Bleeding 2.9%

Perforation 1%

Sepsis 6%

Stent occlusion 0.86%

Migration 0.8%

Bleeding 0.86%

Death 1.7%

Fever 13.6%

Stent migration 2.3%

Bleeding 3.4%

Bleeding 3.3%

Infection 4.8%

Bleeding 5.7%

Perforation 2.1%

Infection 2.1%

Bleeding 5.1%

Perforation 1.7%

*Endoscopic Management of Pancreatic Fluid Collections: An Update*

*DOI: http://dx.doi.org/10.5772/intechopen.89764*


**Table 1.**

*Outcome of endoscopic transmural drainage in pancreatic fluid collections using large caliber metal stents.*

#### *Endoscopic Management of Pancreatic Fluid Collections: An Update DOI: http://dx.doi.org/10.5772/intechopen.89764*

*Pancreatitis*

**Figure 5.**

and endoscopic ultrasound (EUS) are better imaging modalities for qualitative assessment of PFCs. We perform both CECT and EUS to define the anatomical relation of PFCs to the lumen and characterize them into pseudocyst or WON, respectively. The technique of endoscopic drainage of PFCs involves the following steps: puncture of the cysto-gastric or cysto-duodenal wall using a 19 gauge needle and aspiration of cyst contents, coiling of guidewire within the cyst cavity under fluoroscopy guidance, dilatation of the tract using cystotome and balloon and deployment of plastic or metal endoprostheses. EUS guided drainage is preferred to endoscopic approach as intervening vessels can be avoided and non-bulging collec-

*CT image in a case of walled off necrosis replacing almost entire pancreas. Note that the necrotic contents of the* 

The success rate of ETD with or without endoscopic necrosectomy ranges from 80 to 95% in recent studies [11–19] (**Table 1**). The outcomes of ETD of PFCs is variable in literature presumably due to heterogeneity in the nature of collection, that is, pseudocyst or WON, type of stent used, and whether necrosectomy is performed or not [20]. In addition, the presence of disconnected pancreatic duct (DPD) may impact the outcomes of ETD. The requirement of hybrid treatment, re-interventions, recurrences, and rescue surgery appear to be higher in the patients

ETD of PFCs is safe, and major complications are uncommon. Complications related to ETD occur in 10–40% of patients with WON [22]. Supra-infection of the cyst cavity is the most common significant complication associated with ETD. Occlusion of the stent with necrotic debris and inadequate drainage may lead to sepsis. In such situations, de-clogging of the metal stent, cyst lavage with saline or diluted hydrogen peroxide and direct endoscopic necrosectomy (DEN) are often helpful. Other complications associated with ETD include bleeding and perforation. Recent studies have drawn attention towards the relatively high incidence of bleeding especially with the use of large caliber metal stents (LCMS) [23–25]. Since, majority of the bleeding episodes occurred ≥3 weeks after the deployment of LCMS, the current trend is to remove LCMS between 2 and 3 weeks in cases of resolution of PFC [24].

Endoscopic drainage of PFCs can be performed using pigtail plastic stents or metal stents. Plastic stents have been effectively used for the drainage of PFCs for

tions can be targeted under vision [10].

*cyst cavity are not obvious in CT image.*

**2.2 Endoscopic transmural drainage: choice of stents**

with DPD [21].

**10**

**11**

several decades now. The proposed advantages of plastic over metal stents include lower cost, less risk of delayed bleeding, and ability to keep them for long term in cases with DPD. On the other hand, metal stents have wider lumen, allowing efficient drainage of the necrotic material and endoscopic necrosectomy when required. Conventional fully covered metal stents used initially were suboptimal due to their longer lengths and lack of lumen apposing properties. The development of novel LCMS has widened the therapeutic armamentarium for ETD of PFCs. Newly developed LCMS have either lumen apposing (AXIOS, Xlumena, Mountain View, CA, United States and Niti-S SPAXUS, TaeWoong Medical Co., Ltd., Ilsan, South Korea) properties or flared ends (NAGI, Taewoong Medical Co, Ilsan, South Korea) to prevent stent migration [10]. As compared to the conventional metal stents, the use of LCMS is associated with superior outcomes in terms of number of procedures required for the resolution of WON [26]. Similarly, better clinical outcomes and reduced requirement of endoscopic necrosectomy have been found with the use of metal stents as compared to plastic stents in several studies [27–30]. In a large, multicenter study including 189 patients with WON, the use of LCMS was associated with higher clinical success (80.4 vs. 57.5%), shorter procedure time, lower need for surgery (5.1 vs. 16.1%), and lower rate of recurrence as compared to plastic stents [31]. However, the superiority of LCMS is not uniform across the published studies. In a randomized trial, there was no significant difference in the treatment outcomes including the total number of procedures performed, treatment success, and readmissions between LCMS and plastic stent groups in patients with WON [24]. In addition, the treatment cost (LCMS: US\$12155 vs. plastic stents: US\$6609) and stent related adverse events were higher in the LCMS group (32.3 vs. 6.9%, p = 0.01) [24]. Several systematic reviews and meta-analyses draw conflicting conclusions while comparing plastic stents vs. metal stents for ETD of PFCs [32–37]. In three of the published systematic reviews and meta-analyses, metal stents were found superior to plastic stents for both pseudocysts as well as WON in terms of clinical success and adverse events [34, 36, 32]. On the contrary, two other systematic reviews and meta-analyses did not find a difference in the outcomes between metal or plastic stents [33, 37]. It must be emphasized that the paucity of randomized trials is the major limitations of these reviews.

The current trend is to use metal stents for WON with significant debris. These cases may require more frequent re-interventions including endoscopic necrosectomy for which LCMS are ideal. Whereas, plastic stents are an cost effective alternative in pseudocysts or WON with minimal necrotic contents. Randomized trials are warranted before concluding the superiority of metal stents for the management of PFCs.

#### **2.3 Endoscopic necrosectomy**

Endoscopic necrosectomy essentially comprises of endoscopic debridement of necrotic debris within the cyst cavity using a variety of methods including DEN and naso-cystic lavage with saline and or diluted hydrogen peroxide (3%, 1:10 dilution). DEN involves the passage of endoscope within the cyst cavity followed by mechanical removal of necrotic tissue using forceps, polypectomy snares, and retrieval nets [38]. With the availability of LCMS (≥15 mm), multiple sessions of DEN can be performed with relative ease. However, there is no dedicated device or accessory for DEN and therefore, the process is cumbersome and time consuming. Recent development of new devices to facilitate endoscopic debridement is likely to make DEN less cumbersome and more efficacious [39, 40].

DEN is safe and effective in about 80–90% of patients with WON. However, DEN may be associated with substantial complications. In a systematic review, the

**13**

**Figure 6.**

*Large pancreatic fluid collection extending into pelvis.*

*Endoscopic Management of Pancreatic Fluid Collections: An Update*

overall rate of adverse events and mortality associated with endoscopic necrosectomy were 22% and 5%, respectively. The complications reported with DEN include air embolism (0.4%), bleeding (11%), and perforation (3%) [41]. Therefore, DEN

Our group re-defined the endoscopic step-up approach in patients with WON. This approach includes cyst cavity lavage using nasocystic catheter and de-clogging of the metal stent as intermediate steps after transmural placement of metal stent and before proceeding to endoscopic necrosectomy [14]. With this approach, endoscopic necrosectomy can be avoided in the vast majority of patients

Open surgery is associated with a high morbidity and mortality in patients with WON. Consequently, minimally invasive surgical or endoscopic approaches have virtually replaced open necrosectomy in these patients [6]. The available evidence favors a step-up approach over the conventional techniques [7, 42–44]. In general, minimally invasive surgical step-up approach consists of percutaneous drainage followed by (if necessary) video assisted retroperitoneal debridement (VARD). Whereas, endoscopic step up approach includes ETD followed by (if necessary) endoscopic necrosectomy. Percutaneous catheter drainage can be used as an adjunct to ETD in cases with incomplete response or large collections with extension into

Several trials have compared endoscopic versus minimally invasive surgical methods of drainage in cases with WON [7, 45]. In a randomized trial by the Dutch Pancreatitis Study Group, there was no difference in the incidence of major complications or mortality between the endoscopic or minimally invasive surgical step-up approach (endoscopy: 43% vs. surgery: 45%, p = 0.88) [7]. However, the rate of

is usually performed in cases with no improvement after ETD alone.

*DOI: http://dx.doi.org/10.5772/intechopen.89764*

**2.4 Step-up approach for walled of necrosis**

paracolic gutter (**Figure 6**).

with WON.

#### *Endoscopic Management of Pancreatic Fluid Collections: An Update DOI: http://dx.doi.org/10.5772/intechopen.89764*

*Pancreatitis*

several decades now. The proposed advantages of plastic over metal stents include lower cost, less risk of delayed bleeding, and ability to keep them for long term in cases with DPD. On the other hand, metal stents have wider lumen, allowing efficient drainage of the necrotic material and endoscopic necrosectomy when required. Conventional fully covered metal stents used initially were suboptimal due to their longer lengths and lack of lumen apposing properties. The development of novel LCMS has widened the therapeutic armamentarium for ETD of PFCs. Newly developed LCMS have either lumen apposing (AXIOS, Xlumena, Mountain View, CA, United States and Niti-S SPAXUS, TaeWoong Medical Co., Ltd., Ilsan, South Korea) properties or flared ends (NAGI, Taewoong Medical Co, Ilsan, South Korea) to prevent stent migration [10]. As compared to the conventional metal stents, the use of LCMS is associated with superior outcomes in terms of number of procedures required for the resolution of WON [26]. Similarly, better clinical outcomes and reduced requirement of endoscopic necrosectomy have been found with the use of metal stents as compared to plastic stents in several studies [27–30]. In a large, multicenter study including 189 patients with WON, the use of LCMS was associated with higher clinical success (80.4 vs. 57.5%), shorter procedure time, lower need for surgery (5.1 vs. 16.1%), and lower rate of recurrence as compared to plastic stents [31]. However, the superiority of LCMS is not uniform across the published studies. In a randomized trial, there was no significant difference in the treatment outcomes including the total number of procedures performed, treatment success, and readmissions between LCMS and plastic stent groups in patients with WON [24]. In addition, the treatment cost (LCMS: US\$12155 vs. plastic stents: US\$6609) and stent related adverse events were higher in the LCMS group (32.3 vs. 6.9%, p = 0.01) [24]. Several systematic reviews and meta-analyses draw conflicting conclusions while comparing plastic stents vs. metal stents for ETD of PFCs [32–37]. In three of the published systematic reviews and meta-analyses, metal stents were found superior to plastic stents for both pseudocysts as well as WON in terms of clinical success and adverse events [34, 36, 32]. On the contrary, two other systematic reviews and meta-analyses did not find a difference in the outcomes between metal or plastic stents [33, 37]. It must be emphasized that the paucity of

randomized trials is the major limitations of these reviews.

DEN less cumbersome and more efficacious [39, 40].

The current trend is to use metal stents for WON with significant debris. These

Endoscopic necrosectomy essentially comprises of endoscopic debridement of necrotic debris within the cyst cavity using a variety of methods including DEN and naso-cystic lavage with saline and or diluted hydrogen peroxide (3%, 1:10 dilution). DEN involves the passage of endoscope within the cyst cavity followed by mechanical removal of necrotic tissue using forceps, polypectomy snares, and retrieval nets [38]. With the availability of LCMS (≥15 mm), multiple sessions of DEN can be performed with relative ease. However, there is no dedicated device or accessory for DEN and therefore, the process is cumbersome and time consuming. Recent development of new devices to facilitate endoscopic debridement is likely to make

DEN is safe and effective in about 80–90% of patients with WON. However, DEN may be associated with substantial complications. In a systematic review, the

cases may require more frequent re-interventions including endoscopic necrosectomy for which LCMS are ideal. Whereas, plastic stents are an cost effective alternative in pseudocysts or WON with minimal necrotic contents. Randomized trials are warranted before concluding the superiority of metal stents for the

**12**

management of PFCs.

**2.3 Endoscopic necrosectomy**

overall rate of adverse events and mortality associated with endoscopic necrosectomy were 22% and 5%, respectively. The complications reported with DEN include air embolism (0.4%), bleeding (11%), and perforation (3%) [41]. Therefore, DEN is usually performed in cases with no improvement after ETD alone.

Our group re-defined the endoscopic step-up approach in patients with WON. This approach includes cyst cavity lavage using nasocystic catheter and de-clogging of the metal stent as intermediate steps after transmural placement of metal stent and before proceeding to endoscopic necrosectomy [14]. With this approach, endoscopic necrosectomy can be avoided in the vast majority of patients with WON.
