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Endoscopic drainage of pancreatic fluid collections
Pancreatic fluid collections (PFCs) are common after acute pancreatitis but almost always resolve spontaneously. Persistent collections that cause symptoms, become infected, and/or compress vital structures require treatment. Open surgery had traditionally been considered the standard method for this indication;1 Given its inherently less invasive nature, endoscopic transmural drainage (ETMD) has become a mainstay of this step-up philosophy – it is now the dominant strategy for pseudocyst drainage and, on the basis of emerging randomized trial data, compares very favorably with surgery for the treatment of walled-off necrosis (WON).
According to the step-up approach, the initial treatment of symptomatic and/or infected collections that are within 4 weeks of an attack of pancreatitis involves conservative management because the wall of the collection is typically immature; the systemic inflammation may be significantly exacerbated by definitive drainage, particularly surgery. In this early phase, failure of conservative management is addressed by percutaneous catheter placement, stepping up to a minimally invasive operation if the response to percutaneous drainage and antibiotics is insufficient.
Collections that are at least 4 weeks from the onset of acute pancreatitis are considered mature and termed pseudocysts or WONs depending on whether they contain pure fluid or necrotic tissue. In this phase, endoscopic treatment plays a primary management role because these collections are generally adherent to the stomach or duodenal wall and their capsule is organized enough to withstand endoscopic intervention. If treatment can be held off until this phase, then percutaneous and surgical drainage can often be avoided.
In practice, the 4-week rule holds true for most, but not all, PFCs. ETMD can be performed in some particularly mature collections prior to 4 weeks if the indication is strong and the collection appears to have a mature wall. However, the potential for cyst wall perforation is higher and should be considered in the risk-benefit discussion. Conversely, some collections beyond 4 weeks lack an adequately organized wall and require additional time for maturation.
While endoscopic drainage of pseudocysts has essentially supplanted surgery, the management of WON is more complex and remains multidisciplinary. Two recent randomized trials demonstrated no difference in major complications and/or death between a surgical and endoscopic step-up strategy for WON.2,3 Rates of pancreatic fistulae, hospital stay, and overall treatment costs, however, favored endoscopy. Nevertheless, defining the ideal strategy for many of these patients with complexity requires multidisciplinary discussion. Surgery continues to play a primary role in several scenarios, including collections that are not close to the upper GI tract, those that are particularly complex and extend caudally, and situations in which the endoscopic progress is too slow.
The three most important questions when deciding to embark on ETMD are: (1) whether drainage is indicated (that is, is the patient symptomatic or is there evidence that the PFC is infected?), (2) whether the wall of the collection is adequately mature and apposed to the GI tract wall; and (3) whether the collection contains necrosis? This last question has critical implications in the technical approach to drainage. While CT scan with IV contrast is accurate for assessing wall maturity, it is inadequate to evaluate the presence or quantity of necrosum. Transabdominal ultrasound, endoscopic ultrasound, and MRI (on a T2 sequence) are all superior for this purpose. MRI has the additional benefit of assessing the pancreatic duct integrity, which may influence subsequent management.
Pseudocysts can be managed by cyst-gastrostomy or cyst-duodenostomy alone, whereas most WONs require the additional step of endoscopic necrosectomy – the process of entering the cyst cavity to mechanically debride necrotic tissue. Because of a higher rate of technical success, endoscopic ultrasound–directed creation of the transmural drainage pathway has become standard practice. In addition, it is likely safer, allowing for the identification and avoidance of interceding vessels and other vital structures. The role of endoscopic retrograde cholangiopancreatography with pancreatic stent placement as primary therapy for PFCs is limited to the drainage of small collections (<5 cm), for which it is the preferred treatment strategy. It is as effective as ETMD, which may not be feasible or safe for small PFCs.
Plastic double-pigtail stents have traditionally been used to maintain the transmural tract for both pseudocyst and WON. Recently, however, metallic stents have become more popular. Fully covered biliary self-expanding metallic stents (SEMS) are easier to place, have a larger lumen, and are associated with improved outcomes, compared with plastic stents in observational studies of pseudocyst drainage. Lumen-apposing metallic stents (LAMS) have become the preferred prosthesis for WON drainage given the ability to near-simultaneously establish access and deploy the stent, as well as their much larger caliber lumen which permits seamless entry into the cavity with an endoscope. Based on ease and efficiency of use, LAMS are also commonly employed for pseudocyst drainage, although entry into the cavity is unnecessary.
Plastic stents have been shown to be more cost effective than LAMS for pseudocyst drainage, although the economics around biliary SEMS in this context have not been explored. Robust comparative effectiveness data defining the optimal prostheses for pseudocysts are needed. The literature comparing LAMS to plastic stents for the management of WON is mixed. Studies have shown LAMS to be more cost effective, but a small randomized trial demonstrated no difference in clinical success or in the number of procedures to achieve WON resolution.4 We generally favor LAMS for WON since large-caliber balloon dilation of the tract seems safer within the lumen of the LAMS (which could seal small perforations and tamponade bleeding vessels) than within a freshly created tract.
Secondary infection of the cavity, usually because of stent occlusion, and bleeding are the most common complications of ETMD. Even in the absence of stent occlusion, contamination of the collection after ETMD is ubiquitous and, as such, we prescribe prophylactic antibiotics for 1-2 weeks after the procedure, although this practice is not evidence based. Hemorrhage appears to be increasing in frequency with the diffusion of LAMS; this has been postulated to be due to particularly rapid cyst cavity collapse resulting in erosion of the stent into contralateral cyst wall vessels. CT angiography followed by an embolization procedure for a possible pseudoaneurysm is the mainstay of treatment. Serious venous bleeding is more challenging to address because angiographic options are limited.
Despite tremendous recent advances, several important controversies in the endoscopic management of PFCs persist. The optimal prosthesis, the importance of first-session endoscopic necroscopy (compared with stepping up to endoscopic necroscopy only if necessary), the roles of adjunctive drain placement and chemical debridement (such as hydrogen peroxide), the need for concomitant pancreatic stent placement, and the preferred long-term management of a disconnected pancreatic duct are areas for which additional research is sorely needed. We further discuss these questions and many additional technical considerations pertaining to endoscopic drainage in a recent review.5
In summary, endoscopic transmural drainage of mature PFCs is effective and safe. Existing evidence supports its use as the favored treatment modality in appropriate candidates and has rendered it a mainstay of the therapeutic armamentarium for this disease. Further studies are needed to address critical unanswered questions and to develop a uniform endoscopic management paradigm.
References
1. van Santvoort HC et al. N Engl J Med. 2010;362(16):1491-502.
2. van Brunschot S et al. Lancet. 2018;391(10115):51-8.
3. Bang JY et al. Gastroenterology. 2019;156(4):1027-40.
4. Bang JY et al. Gut. 2019;68(7):1200-9.
5. Elmunzer BJ. Clin Gastroenterol Hepatol. 2018;16(12):1851-63.
Dr. Moran is assistant professor of medicine, division of gastroenterology and hepatology, Medical University of South Carolina, Charleston; Dr. Elmunzer is the Peter Cotton Professor of Medicine and Endoscopic Innovation, division of gastroenterology and hepatology, Medical University of South Carolina. The authors have no conflicts of interest pertaining to this review.
Pancreatic fluid collections (PFCs) are common after acute pancreatitis but almost always resolve spontaneously. Persistent collections that cause symptoms, become infected, and/or compress vital structures require treatment. Open surgery had traditionally been considered the standard method for this indication;1 Given its inherently less invasive nature, endoscopic transmural drainage (ETMD) has become a mainstay of this step-up philosophy – it is now the dominant strategy for pseudocyst drainage and, on the basis of emerging randomized trial data, compares very favorably with surgery for the treatment of walled-off necrosis (WON).
According to the step-up approach, the initial treatment of symptomatic and/or infected collections that are within 4 weeks of an attack of pancreatitis involves conservative management because the wall of the collection is typically immature; the systemic inflammation may be significantly exacerbated by definitive drainage, particularly surgery. In this early phase, failure of conservative management is addressed by percutaneous catheter placement, stepping up to a minimally invasive operation if the response to percutaneous drainage and antibiotics is insufficient.
Collections that are at least 4 weeks from the onset of acute pancreatitis are considered mature and termed pseudocysts or WONs depending on whether they contain pure fluid or necrotic tissue. In this phase, endoscopic treatment plays a primary management role because these collections are generally adherent to the stomach or duodenal wall and their capsule is organized enough to withstand endoscopic intervention. If treatment can be held off until this phase, then percutaneous and surgical drainage can often be avoided.
In practice, the 4-week rule holds true for most, but not all, PFCs. ETMD can be performed in some particularly mature collections prior to 4 weeks if the indication is strong and the collection appears to have a mature wall. However, the potential for cyst wall perforation is higher and should be considered in the risk-benefit discussion. Conversely, some collections beyond 4 weeks lack an adequately organized wall and require additional time for maturation.
While endoscopic drainage of pseudocysts has essentially supplanted surgery, the management of WON is more complex and remains multidisciplinary. Two recent randomized trials demonstrated no difference in major complications and/or death between a surgical and endoscopic step-up strategy for WON.2,3 Rates of pancreatic fistulae, hospital stay, and overall treatment costs, however, favored endoscopy. Nevertheless, defining the ideal strategy for many of these patients with complexity requires multidisciplinary discussion. Surgery continues to play a primary role in several scenarios, including collections that are not close to the upper GI tract, those that are particularly complex and extend caudally, and situations in which the endoscopic progress is too slow.
The three most important questions when deciding to embark on ETMD are: (1) whether drainage is indicated (that is, is the patient symptomatic or is there evidence that the PFC is infected?), (2) whether the wall of the collection is adequately mature and apposed to the GI tract wall; and (3) whether the collection contains necrosis? This last question has critical implications in the technical approach to drainage. While CT scan with IV contrast is accurate for assessing wall maturity, it is inadequate to evaluate the presence or quantity of necrosum. Transabdominal ultrasound, endoscopic ultrasound, and MRI (on a T2 sequence) are all superior for this purpose. MRI has the additional benefit of assessing the pancreatic duct integrity, which may influence subsequent management.
Pseudocysts can be managed by cyst-gastrostomy or cyst-duodenostomy alone, whereas most WONs require the additional step of endoscopic necrosectomy – the process of entering the cyst cavity to mechanically debride necrotic tissue. Because of a higher rate of technical success, endoscopic ultrasound–directed creation of the transmural drainage pathway has become standard practice. In addition, it is likely safer, allowing for the identification and avoidance of interceding vessels and other vital structures. The role of endoscopic retrograde cholangiopancreatography with pancreatic stent placement as primary therapy for PFCs is limited to the drainage of small collections (<5 cm), for which it is the preferred treatment strategy. It is as effective as ETMD, which may not be feasible or safe for small PFCs.
Plastic double-pigtail stents have traditionally been used to maintain the transmural tract for both pseudocyst and WON. Recently, however, metallic stents have become more popular. Fully covered biliary self-expanding metallic stents (SEMS) are easier to place, have a larger lumen, and are associated with improved outcomes, compared with plastic stents in observational studies of pseudocyst drainage. Lumen-apposing metallic stents (LAMS) have become the preferred prosthesis for WON drainage given the ability to near-simultaneously establish access and deploy the stent, as well as their much larger caliber lumen which permits seamless entry into the cavity with an endoscope. Based on ease and efficiency of use, LAMS are also commonly employed for pseudocyst drainage, although entry into the cavity is unnecessary.
Plastic stents have been shown to be more cost effective than LAMS for pseudocyst drainage, although the economics around biliary SEMS in this context have not been explored. Robust comparative effectiveness data defining the optimal prostheses for pseudocysts are needed. The literature comparing LAMS to plastic stents for the management of WON is mixed. Studies have shown LAMS to be more cost effective, but a small randomized trial demonstrated no difference in clinical success or in the number of procedures to achieve WON resolution.4 We generally favor LAMS for WON since large-caliber balloon dilation of the tract seems safer within the lumen of the LAMS (which could seal small perforations and tamponade bleeding vessels) than within a freshly created tract.
Secondary infection of the cavity, usually because of stent occlusion, and bleeding are the most common complications of ETMD. Even in the absence of stent occlusion, contamination of the collection after ETMD is ubiquitous and, as such, we prescribe prophylactic antibiotics for 1-2 weeks after the procedure, although this practice is not evidence based. Hemorrhage appears to be increasing in frequency with the diffusion of LAMS; this has been postulated to be due to particularly rapid cyst cavity collapse resulting in erosion of the stent into contralateral cyst wall vessels. CT angiography followed by an embolization procedure for a possible pseudoaneurysm is the mainstay of treatment. Serious venous bleeding is more challenging to address because angiographic options are limited.
Despite tremendous recent advances, several important controversies in the endoscopic management of PFCs persist. The optimal prosthesis, the importance of first-session endoscopic necroscopy (compared with stepping up to endoscopic necroscopy only if necessary), the roles of adjunctive drain placement and chemical debridement (such as hydrogen peroxide), the need for concomitant pancreatic stent placement, and the preferred long-term management of a disconnected pancreatic duct are areas for which additional research is sorely needed. We further discuss these questions and many additional technical considerations pertaining to endoscopic drainage in a recent review.5
In summary, endoscopic transmural drainage of mature PFCs is effective and safe. Existing evidence supports its use as the favored treatment modality in appropriate candidates and has rendered it a mainstay of the therapeutic armamentarium for this disease. Further studies are needed to address critical unanswered questions and to develop a uniform endoscopic management paradigm.
References
1. van Santvoort HC et al. N Engl J Med. 2010;362(16):1491-502.
2. van Brunschot S et al. Lancet. 2018;391(10115):51-8.
3. Bang JY et al. Gastroenterology. 2019;156(4):1027-40.
4. Bang JY et al. Gut. 2019;68(7):1200-9.
5. Elmunzer BJ. Clin Gastroenterol Hepatol. 2018;16(12):1851-63.
Dr. Moran is assistant professor of medicine, division of gastroenterology and hepatology, Medical University of South Carolina, Charleston; Dr. Elmunzer is the Peter Cotton Professor of Medicine and Endoscopic Innovation, division of gastroenterology and hepatology, Medical University of South Carolina. The authors have no conflicts of interest pertaining to this review.
Pancreatic fluid collections (PFCs) are common after acute pancreatitis but almost always resolve spontaneously. Persistent collections that cause symptoms, become infected, and/or compress vital structures require treatment. Open surgery had traditionally been considered the standard method for this indication;1 Given its inherently less invasive nature, endoscopic transmural drainage (ETMD) has become a mainstay of this step-up philosophy – it is now the dominant strategy for pseudocyst drainage and, on the basis of emerging randomized trial data, compares very favorably with surgery for the treatment of walled-off necrosis (WON).
According to the step-up approach, the initial treatment of symptomatic and/or infected collections that are within 4 weeks of an attack of pancreatitis involves conservative management because the wall of the collection is typically immature; the systemic inflammation may be significantly exacerbated by definitive drainage, particularly surgery. In this early phase, failure of conservative management is addressed by percutaneous catheter placement, stepping up to a minimally invasive operation if the response to percutaneous drainage and antibiotics is insufficient.
Collections that are at least 4 weeks from the onset of acute pancreatitis are considered mature and termed pseudocysts or WONs depending on whether they contain pure fluid or necrotic tissue. In this phase, endoscopic treatment plays a primary management role because these collections are generally adherent to the stomach or duodenal wall and their capsule is organized enough to withstand endoscopic intervention. If treatment can be held off until this phase, then percutaneous and surgical drainage can often be avoided.
In practice, the 4-week rule holds true for most, but not all, PFCs. ETMD can be performed in some particularly mature collections prior to 4 weeks if the indication is strong and the collection appears to have a mature wall. However, the potential for cyst wall perforation is higher and should be considered in the risk-benefit discussion. Conversely, some collections beyond 4 weeks lack an adequately organized wall and require additional time for maturation.
While endoscopic drainage of pseudocysts has essentially supplanted surgery, the management of WON is more complex and remains multidisciplinary. Two recent randomized trials demonstrated no difference in major complications and/or death between a surgical and endoscopic step-up strategy for WON.2,3 Rates of pancreatic fistulae, hospital stay, and overall treatment costs, however, favored endoscopy. Nevertheless, defining the ideal strategy for many of these patients with complexity requires multidisciplinary discussion. Surgery continues to play a primary role in several scenarios, including collections that are not close to the upper GI tract, those that are particularly complex and extend caudally, and situations in which the endoscopic progress is too slow.
The three most important questions when deciding to embark on ETMD are: (1) whether drainage is indicated (that is, is the patient symptomatic or is there evidence that the PFC is infected?), (2) whether the wall of the collection is adequately mature and apposed to the GI tract wall; and (3) whether the collection contains necrosis? This last question has critical implications in the technical approach to drainage. While CT scan with IV contrast is accurate for assessing wall maturity, it is inadequate to evaluate the presence or quantity of necrosum. Transabdominal ultrasound, endoscopic ultrasound, and MRI (on a T2 sequence) are all superior for this purpose. MRI has the additional benefit of assessing the pancreatic duct integrity, which may influence subsequent management.
Pseudocysts can be managed by cyst-gastrostomy or cyst-duodenostomy alone, whereas most WONs require the additional step of endoscopic necrosectomy – the process of entering the cyst cavity to mechanically debride necrotic tissue. Because of a higher rate of technical success, endoscopic ultrasound–directed creation of the transmural drainage pathway has become standard practice. In addition, it is likely safer, allowing for the identification and avoidance of interceding vessels and other vital structures. The role of endoscopic retrograde cholangiopancreatography with pancreatic stent placement as primary therapy for PFCs is limited to the drainage of small collections (<5 cm), for which it is the preferred treatment strategy. It is as effective as ETMD, which may not be feasible or safe for small PFCs.
Plastic double-pigtail stents have traditionally been used to maintain the transmural tract for both pseudocyst and WON. Recently, however, metallic stents have become more popular. Fully covered biliary self-expanding metallic stents (SEMS) are easier to place, have a larger lumen, and are associated with improved outcomes, compared with plastic stents in observational studies of pseudocyst drainage. Lumen-apposing metallic stents (LAMS) have become the preferred prosthesis for WON drainage given the ability to near-simultaneously establish access and deploy the stent, as well as their much larger caliber lumen which permits seamless entry into the cavity with an endoscope. Based on ease and efficiency of use, LAMS are also commonly employed for pseudocyst drainage, although entry into the cavity is unnecessary.
Plastic stents have been shown to be more cost effective than LAMS for pseudocyst drainage, although the economics around biliary SEMS in this context have not been explored. Robust comparative effectiveness data defining the optimal prostheses for pseudocysts are needed. The literature comparing LAMS to plastic stents for the management of WON is mixed. Studies have shown LAMS to be more cost effective, but a small randomized trial demonstrated no difference in clinical success or in the number of procedures to achieve WON resolution.4 We generally favor LAMS for WON since large-caliber balloon dilation of the tract seems safer within the lumen of the LAMS (which could seal small perforations and tamponade bleeding vessels) than within a freshly created tract.
Secondary infection of the cavity, usually because of stent occlusion, and bleeding are the most common complications of ETMD. Even in the absence of stent occlusion, contamination of the collection after ETMD is ubiquitous and, as such, we prescribe prophylactic antibiotics for 1-2 weeks after the procedure, although this practice is not evidence based. Hemorrhage appears to be increasing in frequency with the diffusion of LAMS; this has been postulated to be due to particularly rapid cyst cavity collapse resulting in erosion of the stent into contralateral cyst wall vessels. CT angiography followed by an embolization procedure for a possible pseudoaneurysm is the mainstay of treatment. Serious venous bleeding is more challenging to address because angiographic options are limited.
Despite tremendous recent advances, several important controversies in the endoscopic management of PFCs persist. The optimal prosthesis, the importance of first-session endoscopic necroscopy (compared with stepping up to endoscopic necroscopy only if necessary), the roles of adjunctive drain placement and chemical debridement (such as hydrogen peroxide), the need for concomitant pancreatic stent placement, and the preferred long-term management of a disconnected pancreatic duct are areas for which additional research is sorely needed. We further discuss these questions and many additional technical considerations pertaining to endoscopic drainage in a recent review.5
In summary, endoscopic transmural drainage of mature PFCs is effective and safe. Existing evidence supports its use as the favored treatment modality in appropriate candidates and has rendered it a mainstay of the therapeutic armamentarium for this disease. Further studies are needed to address critical unanswered questions and to develop a uniform endoscopic management paradigm.
References
1. van Santvoort HC et al. N Engl J Med. 2010;362(16):1491-502.
2. van Brunschot S et al. Lancet. 2018;391(10115):51-8.
3. Bang JY et al. Gastroenterology. 2019;156(4):1027-40.
4. Bang JY et al. Gut. 2019;68(7):1200-9.
5. Elmunzer BJ. Clin Gastroenterol Hepatol. 2018;16(12):1851-63.
Dr. Moran is assistant professor of medicine, division of gastroenterology and hepatology, Medical University of South Carolina, Charleston; Dr. Elmunzer is the Peter Cotton Professor of Medicine and Endoscopic Innovation, division of gastroenterology and hepatology, Medical University of South Carolina. The authors have no conflicts of interest pertaining to this review.