INTRODUCTION — Pancreatic debridement is indicated for patients with pancreatic necrosis and progressive clinical sepsis as a complication of severe acute pancreatitis [1,2]. Pancreatic and peripancreatic necrosis occurs in approximately 20 percent of patients with pancreatitis, as a result of inflammation and vascular compromise [3,4].

The indications and techniques for pancreatic debridement will be reviewed here. The etiology, diagnosis, and general approach to the treatment of acute pancreatitis is discussed elsewhere. (See "Etiology of acute pancreatitis" and "Clinical manifestations and diagnosis of acute pancreatitis" and "Predicting the severity of acute pancreatitis" and "Management of acute pancreatitis".)

INDICATIONS FOR PANCREATIC DEBRIDEMENT — Pancreatic necrosis can lead to secondary infection or symptomatic sterile necrosis, which is characterized by chronic low-grade fever, nausea, lethargy, and inability to eat [5-8]. Both infected pancreatic necrosis and symptomatic sterile necrosis are accepted indications for debridement [5,8,9].

The goal of pancreatic debridement is to excise all dead and devitalized pancreatic and peripancreatic tissue while preserving viable functioning pancreas, controlling resultant pancreatic fistulas, and limiting extraneous organ damage [1,7]. For patients with biliary pancreatitis, cholecystectomy with intraoperative cholangiography is an important secondary objective of the surgery because it will prevent recurrent disease [10].

Infected pancreatic necrosis — Secondary infection of the necrotic pancreatic or peripancreatic tissue with either bacteria or fungus occurs soon after the initial inflammatory reaction subsides and is heralded by tachycardia, hypotension, fevers, and/or deteriorating organ function [11]. Bacterial or fungal infections occur either by bacterial translocation from the gastrointestinal tract or via seeding through transient bacteremia that can occur in the setting of invasive intravenous lines, endotracheal intubation, or prolonged bladder catheterization. The risk of secondary bacterial infections can be minimized with early enteral feeding, central line catheter maintenance programs, ventilator protocols, and early urinary catheter removal [12-14].

There is no benefit from probiotics, protease inhibitors, or early surgical debridement for the prevention of infected pancreatic necrosis [15-19]. The use of prophylactic systemic antibiotics in acute pancreatitis is controversial and is discussed in detail elsewhere. (See "Management of acute pancreatitis", section on 'Acute necrotic collection and walled-off necrosis'.)

Symptomatic sterile pancreatic necrosis — Symptomatic sterile necrosis is characterized by chronic low-grade fever, nausea, lethargy, and inability to eat. These patients typically have a large volume of retroperitoneal necrosis and often harbor occult infections identified only after debridement [9]. Medical treatment with total parenteral nutrition and antibiotics is often effective, but pancreatic debridement may be required in patients who do not respond to medical therapy [8,9,20]. The optimal timing of surgical intervention for symptomatic sterile necrosis, however, is controversial [21]. (See 'Timing of debridement' below.)

TIMING OF DEBRIDEMENT — Pancreatic necrosis is a dynamic disease process that evolves in two distinct clinical phases (early and late), which affect the timing of debridement (figure 1) [1]. For the reasons described below, late debridement is preferred, if possible, at least three to four weeks following the onset of acute pancreatitis. Delayed debridement allows clinical stabilization of the patient, resolution of early organ failure, and a decrease in the intense inflammatory reaction in the retroperitoneum [22,23]. The initial management of acute pancreatitis is discussed elsewhere. (See "Management of acute pancreatitis".)

●Early phase – The early phase of illness (first two weeks) is characterized by an acute systemic inflammatory response syndrome, organ dysfunction or failure, and variable amounts of pancreatic and peripancreatic ischemia, leading to tissue necrosis. The underlying mechanism for this phase of disease is believed to be the host's inflammatory and cytokine response, resulting in organ dysfunction [24].

During the first few days of critical illness, early death from irreversible organ failure accounts for up to 60 percent of mortality in patients with severe acute pancreatitis [25,26]. This early organ failure, which is predominately renal and pulmonary, can be treated by aggressive volume resuscitation, enteral feeding, and support [7]. (See "Management of acute pancreatitis", section on 'Initial management'.)

Infrequently, exploratory laparotomy is considered to confirm the diagnosis of severe acute pancreatitis and to exclude other potentially treatable causes of recalcitrant multiorgan system failure such as infarcted bowel, gangrenous gallbladder, or perforated viscus. In patients who survive this early inflammatory storm, increased morbidity and mortality rates are due to persistent organ failure, pancreatic necrosis, and/or infection [1,7].

If treatable causes of organ failure are not identified and the etiology is confirmed to be severe acute pancreatitis with necrosis, early pancreatic debridement is rarely helpful. Early debridement is often complicated by intra-abdominal hypervascularity, altered anatomic relationships, and an inability to discriminate dead from surrounding live tissue, making debridement imprecise, bloody, and ineffective. When infected necrosis necessitates early debridement, the debridement often is associated with incomplete removal of necrotic tissue and a high rate of injury to normal surrounding tissues [19,22,23]. These patients have a higher morbidity and mortality rate and frequently require multiple surgical procedures for persistent pancreatic necrosis or repair of iatrogenic damage to the surrounding organs [27].

●Late phase – The optimal time for surgical debridement is approximately four weeks after the onset of pancreatitis, when vascular inflammation has decreased, organization of the process has occurred, and delineation of live from dead tissue is complete [28]. At this point, the retroperitoneal inflammatory response decreases and the necrotic areas are demarcated from the surrounding viable tissue, which usually permits definitive operative debridement. The organized, demarcated collection is termed walled-off pancreatic necrosis [29,30]. (See 'Walled-off pancreatic necrosis' below.)

PREOPERATIVE EVALUATION AND PREPARATION — The preoperative evaluation and preparation of patients with pancreatic necrosis will depend upon the etiology of the pancreatitis. However, all patients need a preoperative computed tomography (CT) scan to define the extent and location of the disease. (See "Etiology of acute pancreatitis".)

Ultrasound — All patients suspected of having biliary pancreatitis require preoperative ultrasound evaluation to confirm the presence of gallstones. In those suspected of having choledocholithiasis, preoperative liver function tests are also important [10]. (See "Etiology of acute pancreatitis", section on 'Gallstones'.)

ERCP — Patients with evidence of cholangitis or biliary obstruction should undergo prompt endoscopic retrograde cholangiopancreatography (ERCP) to ameliorate the severity of the pancreatitis [31,32]. Patients with acute pancreatitis but not cholangitis or biliary obstruction do not benefit from early ERCP [33]. (See "Acute cholangitis: Clinical manifestations, diagnosis, and management", section on 'Biliary drainage' and "Overview of endoscopic retrograde cholangiopancreatography (ERCP) in adults", section on 'Patient selection'.)

CT scan — The diagnosis of infected pancreatic necrosis is made by the identification of air bubbles in retroperitoneal necrosis on CT (image 1) and/or with CT-directed fine-needle aspiration of pancreatic necrosis for gram stain and culture [29,34]. The use of CT-directed fine-needle aspiration confirms the diagnosis of infected pancreatic necrosis and supports the decision for surgical debridement. However, because of potential adverse effects, fine-needle aspiration should be performed only when the results will affect intervention [35]. (See "Management of acute pancreatitis", section on 'Acute necrotic collection and walled-off necrosis'.)

All patients with pancreatic necrosis undergoing debridement should have contrast-enhanced CT scanning of the abdomen and pelvis to define the extent and location of necrotic areas as this will affect the surgical approach. In some cases, CT placement of drains should be considered as a bridging technique to decompress retroperitoneal fluid collections and to allow stabilization of patients with sepsis prior to operative debridement. (See 'Percutaneous CT-guided catheter drainage' below.)

Estimating the extent of disease — Accurate quantification of the extent of pancreatic parenchymal and peripancreatic necrosis, documentation of diffuse or walled-off necrosis, and identification of infection are critical for prediction of a patient's clinical course and choice of the most appropriate therapy [1,5,36-38]. Areas of necrosis are manifested on contrast-enhanced CT by a lack of tissue contrast enhancement (fewer than 50 Hounsfield units) (image 2) [36,39]. The lack of contrast is due to capillary thrombosis and documents the lack of blood supply to the area of necrosis [40]. Use of CT findings to predict outcome is outlined in the table and discussed in detail elsewhere (table 1). (See "Predicting the severity of acute pancreatitis", section on 'CT severity index'.)

Disconnected pancreatic segment — In patients with isolated necrosis of the pancreatic neck or body, note should be made of the presence of a disconnected pancreatic segment. A disconnected segment will remain viable after debridement and will require adequate external drainage to create a controlled external pancreatic fistula and prevent internal leaking of pancreatic fluids [41]. (See "Pancreatic fistulas: Management".)

Extension into mesenteric root — Extension of the necrotic process into the mesenteric root (image 3) and down the right and left paracolic gutters is common and should be treated with wide surgical debridement and drainage. Mobilization of the colon (eg, splenic flexure mobilization) is not advised in this setting, as the risk of colonic devascularization is high. Occasionally, the necrotic process involves the mesocolon to such an extent that adequate debridement skeletonizes the colonic blood supply, leaving the colon vulnerable to ischemic injury. In this situation, partial colectomy with end ileostomy and Hartmann's procedure is the safest and most expedient way to remove jeopardized colon, divert the fecal stream, and ensure prompt recovery and the ability to establish early enteral feeding. Patients potentially at risk for this outcome should be informed of this possibility preoperatively and be visited by an enterostomal therapist for marking. (See "Ileostomy or colostomy care and complications".)

Walled-off pancreatic necrosis — Walled-off pancreatic necrosis is an increasingly well-recognized entity in which encapsulation of the process within the lesser sac bound by the stomach, duodenum, transverse mesocolon, and omentum creates a localized mature collection analogous to a pancreatic pseudocyst (image 4 and image 5) [38]. It is best defined by cross-sectional imaging (contrast-enhanced CT). Walled-off pancreatic necrosis is well suited to minimally invasive debridement techniques, including endoscopic transgastric drainage, external percutaneous drainage with irrigation (image 6 and image 7), and laparoscopic video-assisted retroperitoneal debridement. In the 2014 updated Atlanta classification of acute pancreatitis, walled-off pancreatic necrosis is one of several recognized local complications (others include acute peripancreatic fluid collection, acute necrotic collection, pancreatic pseudocyst, gastric outlet obstruction, splenic or portal vein thrombosis, and colonic necrosis) [42]. (See "Clinical manifestations and diagnosis of acute pancreatitis", section on 'Local complications'.)

NONSURGICAL APPROACHES TO PANCREATIC DEBRIDEMENT — Patients who require pancreatic debridement should be treated in a tertiary referral center where surgical, endoscopic, and radiologic expertise is available; the initial and subsequent approaches should be selected based on patient characteristics, location of the collections, and degree of encapsulation. In suitable candidates, a "step-up" approach of percutaneous drainage and/or endoscopic drainage/debridement provides minimally invasive alternatives to open surgery that can be equally effective [43] and may be associated with reduced mortality [44].

●The PANTER study (PAncreatitis, Necrosectomy versus sTEp up appRoach), a randomized trial of percutaneous catheter drainage in 88 patients, found that 35 percent of patients were treated successfully with percutaneous catheter drainage alone, while the remainder required percutaneous drainage followed by video-assisted retroperitoneal debridement (VARD) [45,46]. Compared with open pancreatic debridement, preoperative drainage followed by VARD significantly decreased the rate of new-onset multiple organ failure (12 versus 40 percent), incisional hernias (7 versus 24 percent), and new-onset diabetes (16 versus 38 percent) but did not significantly affect mortality.

●Another multicenter Dutch trial compared endoscopic catheter drainage followed by endoscopic necrosectomy (if necessary) with percutaneous catheter drainage followed by VARD (if necessary) [47]. Ninety-eight patients with infected pancreatic necrosis were randomly assigned after four weeks since the onset of symptoms to ensure that they had at least partial encapsulation of the necrotic collection. Forty-three and 51 percent of patients in the endoscopic and VARD groups, respectively, only required catheter drainage. Compared with surgery, endoscopic treatment resulted in similar mortality plus major morbidity rate at six months (43 versus 45 percent) but lower incidence of cardiovascular organ failure (6 versus 19 percent), fewer pancreatic fistulas (5 versus 32 percent), and a shorter hospital stay (by 16 days). Approximately one-third of patients treated endoscopically required additional percutaneous catheter drainage or VARD.

●A network meta-analysis of seven studies including 400 patients with infected pancreatic necrosis found that the step-up approach with endoscopic debridement had the highest probability of being the safest approach (SUCRA 87.1 percent), followed by step-up approach with delayed minimally invasive surgical debridement (SUCRA 59.5 percent); delayed surgical debridement, early surgical debridement, and peritoneal lavage had the lowest probability of being safe (SUCRA values 27.6, 31.4, and 44.4 percent, respectively) [28].

Percutaneous CT-guided catheter drainage — Temporary percutaneous drainage can be used to decompress retroperitoneal fluid collections and allow stabilization of patients with sepsis prior to formal operative debridement [48,49]. Computed tomography (CT) guidance is used to establish percutaneous access into pancreatic fluid collections using the most direct transperitoneal route available, thereby avoiding intervening bowel and solid organs. The number and size of catheters placed is dictated by the size and location of the space containing the necrosis, the viscosity of the fluid aspirated, and the amount of particulate debris. The procedure is performed with local anesthesia.

After placement, the catheters undergo vigorous manual irrigation with isotonic saline every several days, combined with contrast CT scans to follow the removal of necrotic debris, assess changes in the cavity dimension, and ensure catheter lumen patency. Over time, small-diameter drains are upsized to larger-bore catheters (24 to 28 French) for removal of necrotic debris. CT-guided catheter drainage requires a dedicated interventional radiologist who will perform sequential interventions as necessary [38,50,51]. A drawback to this approach is that all mechanical debridement and tissue evacuation must be performed through limited-diameter catheters, which require frequent replacement and meticulous maintenance.

Although percutaneous catheter drainage was used as a bridging technique for patients who are too unstable to undergo surgical debridement, approximately one-third to one-half of patients can be managed with percutaneous drainage alone [51-53].

One disadvantage to the percutaneous route is the risk of persistent pancreatico-cutaneous fistula. Features that predispose to pancreatico-cutaneous fistulas include communication between the pancreatic collection and the pancreatic duct or complete obstruction of the duct [54,55]. If necessary, percutaneous drainage appears more likely to be successful in patients with normal pancreatic ducts and/or those with ductal strictures but without communication between the pancreatic duct and the pancreatic collection. (See 'Pancreatic fistula' below.)

Endoscopic debridement — Endoscopic debridement is typically performed via a transgastric or transduodenal approach and is limited to patients with walled-off pancreatic necrosis [38,43,56]. (See "Endoscopic interventions for walled-off pancreatic fluid collections".)

Pancreatic debridement is accomplished through the stomach or duodenum without the need for a transabdominal incision. Under conscious sedation or anesthesia, a puncture site is identified by locating a bulge into the gastrointestinal lumen (representing the fluid collection) and/or with endoscopic ultrasound. The fluid collection is then entered, a sample of fluid is aspirated for gram stain and culture, and a cystenterostomy is created using wire-guided balloon dilators. Once the cystenterostomy is established, direct endoscopic debridement can be carried out using a combination of irrigation, snares, baskets, stone retrieval balloons, or other commercial devices [57]. Following mechanical debridement, stents are placed into the cavity. In addition, a nasocystic tube may be placed for postoperative lavage.

In the past, double pigtail plastic catheters were standard for endoscopic drainage procedures. Many centers have replaced pigtail catheters with lumen-apposing metal stents that have wider diameters to facilitate drainage [47]. The materials and techniques, however, are constantly evolving and have not been standardized.

Serial abdominal CT scans are performed every one to two weeks after the intervention to follow the resolution of necrosis. Endoscopic examinations and interventions are carried out as deemed necessary based upon radiologic imaging data and the patient's clinical response.

The endoscopic technique provides a targeted approach to focal pancreatic necrosis with a reduction in the systemic inflammatory response and avoidance of the wound complications that are associated with major laparotomy incisions [38,50]. A meta-analysis of endoscopic drainage for pancreatic necrosis reported a 69 percent success rate, 34 percent morbidity rate, and 2 percent mortality rate [56]. One-third of patients initially treated with endoscopic debridement ultimately need open surgical debridement [40,56].

SURGEON'S SAFETY CHECKLIST FOR PANCREATIC DEBRIDEMENT — The following issues should be addressed by the surgical team prior to pancreatic debridement.

●Informed consent – The indications for debridement and the planned method of debridement should be discussed with the patient. The discussion should include the potential need for multiple interventions or reoperations to drain intra-abdominal fluid collections, remove additional necrotic tissue, or control a pancreatic fistula.

Patients with biliary pancreatitis should be informed that cholecystectomy done in the setting of retroperitoneal inflammation is associated with an increased incidence of postoperative bile leak or biliary injury. Patients with involvement of the mesocolon should be informed of the potential need for colon resection and a colostomy.

●Antibiotics – Patients with pancreatic necrosis should receive preoperative antibiotics. If percutaneous computed tomography (CT)-guided fine-needle aspiration has been performed, the antibiotic choices should reflect the culture and sensitivity results. The most common organisms causing infection in necrotizing pancreatitis include Escherichia coli, Pseudomonas, Klebsiella, and Enterococcus, and the initial recommended antibiotic coverage is with a carbapenem [4,58]. (See "Combination beta-lactamase inhibitors, carbapenems, and monobactams", section on 'Carbapenems'.)

Antibiotics should be administered after the patient arrives in the operating room and before the incision is made. The efficacy of antibiotic prophylaxis decreases if administered more than one hour before surgery. (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults", section on 'Antimicrobial prophylaxis'.)

●Equipment – Appropriate drains and a jejunal feeding tube should be available; a T-tube or low-profile feeding tube is usually used for the jejunal tube. For laparoscopic surgery, video cameras, a videoscope, and laparoscopic equipment are needed. Intraoperative ultrasound equipment is very useful for localization of the retroperitoneal necrosis and the identification of major vascular anatomy.

●Deep venous thrombosis prophylaxis – For patients undergoing general anesthesia, primary prophylaxis for prevention of deep venous thrombosis should be employed (table 2). (See "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

●Imaging – CT scan images should be reviewed and be readily available in the operating room. (See 'CT scan' above.)

●Surgical timeout – A surgical timeout should be performed with the entire operating room team (anesthesiologist, surgeon, nurse, scrub technician) to assure correct patient identity, intended operation, and informed consent (table 3). A preoperative checklist is a good way to assure that all safety issues have been addressed.

SURGICAL APPROACHES TO PANCREATIC DEBRIDEMENT — Surgical pancreatic debridement can be performed with open or laparoscopic techniques [1,7]. Open debridement remains the gold standard and is usually performed with external drainage. Some surgeons prefer internal drainage with a cystgastrostomy. Laparoscopic surgery can be considered in selected patients.

Open debridement with external drainage — Open debridement under general anesthesia with closure over drains is the gold standard for pancreatic debridement. In an observational series of 102 patients, this approach resulted in operative morbidity in 72 percent and mortality in 4 percent; the mean hospital length of stay was 26 days [23]. These results are consistent with those reported from other large surgical series utilizing this technique [9,59,60].

The following steps are performed with open debridement with external drainage:

●Incision – The abdomen is opened through either an upper midline or bilateral subcostal incision. If a colostomy is anticipated, the site should be marked preoperatively.

●Entry into the retroperitoneum – The retroperitoneum is entered through the lesser sac by mobilizing the omentum off the transverse colon. Alternatively, entrance to the lesser sac can be accomplished through an avascular plane in the transverse mesocolon to the right or left of the middle colic vessels [9]. Utilizing preoperative computed tomography (CT) imaging as a guide, specific areas of pancreatic and peripancreatic necrosis and associated fluid collections are identified.

●Debridement – Once the main site of necrosis is entered, fluid is evacuated and debridement is begun by pulling the loosely organized debris away from the firm, inflamed, viable tissue using blunt dissection, finger pinching, ring forceps, and infrequent sharp dissection. Necrotic debris should be cultured for fungus as well as aerobic and anaerobic bacteria.

Viable tissue should be preserved and can be identified by its firm, indurated appearance and consistency, as well as bleeding with manipulation. Major vascular structures are characteristically well preserved, allowing careful skeletonization during the debridement.

Once the main cavity is debrided, any extension of the process is identified by gentle digital palpation from within the main cavity, exploring communicating spaces and extensions of the necrosis throughout the retroperitoneum. Debridement often extends into the fat of the mesocolon or small bowel mesentery. In both of these sites, meticulous care should be taken to avoid vascular injury, particularly to the colic, superior, or inferior mesenteric vessels.

●Cholecystectomy – For patients with biliary pancreatitis, a cholecystectomy should be performed if technically possible, dissecting the gallbladder retrograde from the fundus to the infundibulum. The need for an intraoperative cholangiogram will depend upon whether endoscopic retrograde cholangiopancreatography (ERCP) was performed prior to surgery.

●Feeding tube – Enteral access should be established through a gastrojejunal feeding tube (18 or 22 French T-tube or a low-profile feeding tube) placed via a Stamm-type gastrostomy, directing the distal jejunal feeding port past the pylorus and ligament of Treitz into the first portion of the jejunum (figure 2).

●Drain placement – Two to four large (19 French) closed suction drains are placed at the time of operation, with the number and positioning dictated by the extent of debridement and concern for the development of a postoperative pancreatic fistula.

Open debridement with internal drainage and cystgastrostomy — Open debridement with internal drainage is favored by some surgeons, when feasible [61]. This procedure is only appropriate for patients with walled-off pancreatic necrosis. The surgery is performed via a midline incision into the peritoneal cavity. (See 'Walled-off pancreatic necrosis' above.)

A longitudinal gastrotomy is made along the greater curvature, and the posterior gastric wall is exposed. A needle is used to identify the walled-off pancreatic collection posterior to the stomach. The cavity is then opened with cautery, and an endovascular stapling device is used to create a generous (8 cm) cystgastrostomy. Debridement is then performed. A nasogastric tube is placed in the cavity. A gastrostomy drainage tube (Foley catheter) is placed, and the gastrotomy is closed. The nasogastric tube is then flushed with isotonic saline every four hours for two to three days.

Open packing — Open packing with planned reoperation every 48 to 72 hours until the necrosis is adequately removed is only appropriate when early surgical intervention is required or when the necrosis is too poorly demarcated to permit complete debridement [62] (see 'Timing of debridement' above). The open packing method is effective in controlling intra-abdominal sepsis but mandates multiple laparotomies, which increases overall mortality, the length of hospital stay, and the incidence of postoperative enterocutaneous fistulas and incisional hernias [61]. Because of these concerns, open packing should be utilized sparingly and is primarily indicated for patients with large collections extending across the retroperitoneum and into the retrocolic spaces or when bleeding is difficult to control [40].

A nonadherent gauze should be placed over the exposed stomach and colon to prevent inadvertent debridement of the intestinal tract [40]. Packing is kept moist. Drains are placed at the time of final laparotomy and secondary closure.

Laparoscopic debridement — There are two laparoscopic approaches for pancreatic debridement: video-assisted retroperitoneal debridement and transperitoneal debridement [29,31,63]. Both techniques utilize laparoscopes, video cameras, and similar instrumentation, but significant differences between the two techniques exist. Most published experience is with video-assisted retroperitoneal debridement.

Video-assisted retroperitoneal debridement — The video-assisted retroperitoneal debridement approach requires preoperative percutaneous access to the retroperitoneal space, which is established via interventional radiology. Before surgery, a 12 to 14 French catheter is placed into the dominant fluid collection through a direct access site in the left upper quadrant or flank under radiologic guidance. This catheter provides an anatomic access route, which guides the subsequent operation.

The surgery is performed through an incision made directly over the drain site, which is extended directly down into the necrotic cavity. Long grasping forceps are used for debridement under direct vision. When the debridement extends into the retroperitoneum, a videoscope is inserted through the incision to allow visualization and deep mechanical debridement through the scope. Two large-bore single-lumen drains are then placed in the retroperitoneum under direct vision using the videoscope.

Continuous retroperitoneal lavage with isotonic saline or dialysis fluid is continued postoperatively at a rate of 125 mL/hour, and patients are followed for clinical progression, declining serum C-reactive protein (CRP) levels, and improvement of necrosis on contrast-enhanced CT scans. Repeated debridements are done every 7 to 10 days until the necrosis cavity is seen to be clear of debris and lined by healthy granulation tissue. At this point, irrigation is stopped and external drainage is continued until the output stops and the drains can be removed.

The advantage of video-assisted retroperitoneal debridement is minimizing the risk of peritoneal contamination. The main drawback of this approach is the limited access and visualization, which limits the amount of debris that can be retrieved and leads to multiple interventions. In addition, limited visualization precludes simultaneous cholecystectomy, intraoperative cholangiography, and feeding jejunostomy placement [56]. A meta-analysis of video-assisted retroperitoneal debridement reported a 64 percent success rate, 47 percent morbidity rate, and 14 percent mortality rate [56].

Laparoscopically assisted transperitoneal debridement — The laparoscopic transperitoneal approach to pancreatic debridement uses conventional laparoscopic intraperitoneal access followed by transmesocolic debridement, utilizing one port for the video camera and two additional working ports.

The main drawback of this approach is the potential for peritoneal contamination. In addition, reintervention is usually not possible, because of scar tissue. For these reasons, laparoscopic transperitoneal debridement is most appropriate as a single-stage procedure for patients with walled-off pancreatic necrosis [29,64].

POSTOPERATIVE MANAGEMENT — Early postoperative management after pancreatic debridement focuses on volume replacement, blood glucose control, maintenance of normothermia, and adequate pain control [65]. Patients require large volumes of fluid to maintain tissue perfusion and renal function since they have massive third-space losses. Most patients remain intubated upon leaving the operating room because of the anticipated large fluid shifts over the initial 24 to 36 hours. In the absence of preoperative pulmonary failure, most should be candidates for early ventilator weaning protocols. (See "Weaning from mechanical ventilation: Readiness testing".)

After the first 48 hours of resuscitation, early aggressive enteral feeding can be started through the operatively placed gastrojejunal feeding tube. (See "Nutrition support in critically ill patients: Enteral nutrition".)

POSTOPERATIVE COMPLICATIONS — The reported mortality rate in patients undergoing debridement for pancreatic necrosis ranges from 4 to 25 percent [4,22,23,59]. The mortality rate is related to the extent of necrosis, underlying organ failure, and infection of the necrotic tissue [1,5,36-38]. Complications after pancreatic debridement include intra-abdominal fluid collections, bleeding, pancreatic fistulas, incisional hernias, and pancreatic insufficiency.

Intra-abdominal fluid collections — The most common postoperative complication requiring intervention after debridement is a residual fluid collection [1]. These collections are frequently infected and can result from a pancreatic leak inadequately controlled by the drains placed at surgery or from a hollow viscus injury. Intra-abdominal fluid collections can be identified on computed tomography (CT) scan and are managed with percutaneous drainage [1,5,7]. Reoperation is rarely necessary.

Postoperative bleeding — Bleeding is the most common indication for early re-exploration after pancreatic debridement. Bleeding can occur early or late in the postoperative period and can lead to hemodynamic instability.

●Early postoperative bleeding is usually due to laceration or avulsion of peripancreatic arteries or veins. This complication appears to be more common after minimally invasive debridement, presumably due to the limited field of vision and lack of tactile feedback during necrotic tissue removal. Prompt reoperation and control of bleeding is indicated.

●Late postoperative bleeding is usually caused by rupture of a retroperitoneal pseudoaneurysm, either into the free peritoneal cavity or out of operatively placed drains. Patients who earlier appeared well and have the abrupt onset of tachycardia, hypotension, mental status change, and increased bloody output from their surgically placed drains should be considered to have a visceral pseudoaneurysm until proven otherwise.

The choice of therapy depends upon whether or not the patient is hemodynamically stable. In unstable patients, emergency reoperation is indicated. In patients in whom volume resuscitation leads to a period of cardiovascular stability, visceral angiography with transcatheter embolization is an option. Once control of bleeding is obtained through direct operative ligation, transcatheter embolization, or stent placement, a careful assessment of the retroperitoneum is essential. The retroperitoneum should be evaluated for possible causes of pseudoaneurysm formation, such as sepsis from an infected fluid collection or an uncontrolled pancreatic fistula, or a mechanical process, such as erosion of drains into an artery. Common areas for pseudoaneurysm formation in the setting of pancreatic necrosis are the splenic artery, gastroduodenal artery, pancreaticoduodenal arcade, and dorsal pancreatic artery (image 8 and image 9). (See "Angiographic control of nonvariceal gastrointestinal bleeding in adults", section on 'Embolization'.)

Pancreatic fistula — Pancreatic fistulas commonly occur following pancreatic debridement and are usually identified by the presence of amylase-rich fluid coming from operatively placed drains or following percutaneous drainage of postoperative intra-abdominal or retroperitoneal fluid collections.

Monitoring drain tube output for volume, color, and consistency of effluent should be performed routinely, and a high index of suspicion should be maintained for the development of a postoperative pancreatic fistula, which is defined as drain amylase concentration greater than three times the upper limit of normal for serum amylase. When pancreatic fistulas are identified at a drain site, maintaining adequate external drainage is essential. Our practice is to place additional securing sutures on the fistula drain using a local anesthetic at the bedside to prevent inadvertent dislodgement.

Pancreatic fistulas may be characterized by their anatomic relationship to the pancreatic duct as either a side or end fistula [66].

●Patients with side pancreatic fistulas retain the possibility of fistula closure, either spontaneously or with the help of a decompressive endoscopically placed pancreatic duct stent.

●Patients with an end fistula usually have a disconnected pancreatic segment. If the segment is large, it will continue to secrete amylase-rich fluid indefinitely. The offending segment usually requires removal using a distal pancreatectomy [67]. (See "Pancreatic fistulas: Management" and "Surgical resection of lesions of the body and tail of the pancreas".)

Biliary injury — Cholecystectomy is required for patients with biliary pancreatitis. However, cholecystectomy performed in the setting of retroperitoneal inflammation is associated with an increased incidence of postoperative bile leak or biliary injury. The risk of biliary injury can be reduced by dissecting the gallbladder retrograde from the fundus to the infundibulum. (See "Complications of laparoscopic cholecystectomy", section on 'Diagnosis and management of biliary injuries'.)

Hernias — Open operations for pancreatic debridement have a high rate of incisional hernia. In one study, for example, incisional hernias developed in 42 percent of 149 patients who underwent pancreatic debridement for necrotizing pancreatitis [68]. (See "Overview of abdominal wall hernias in adults", section on 'Ventral incisional hernia'.)

Pancreatic insufficiency — Depending upon the volume of pancreatic necrosis as well as any disconnected pancreatic segments, patients are at risk for both endocrine and exocrine pancreatic insufficiency. Glandular destruction from the inflammatory process results in long-term endocrine and exocrine insufficiencies in 15 to 60 percent of patients of patients who undergo pancreatic debridement, with the degree of dysfunction associated with the magnitude of pancreatic injury and overall length of follow-up [69,70]. (See "Chronic pancreatitis: Clinical manifestations and diagnosis in adults", section on 'Steatorrhea' and "Chronic pancreatitis: Clinical manifestations and diagnosis in adults", section on 'Laboratory findings'.)

Endocrine insufficiency is indicated by the need for supplemental insulin for hyperglycemia early in the postoperative course. As the patient transitions into the late postoperative period, insulin requirements are covered with a twice-a-day long-acting insulin as well as a sliding scale around meals based on carbohydrates consumed. Long-term therapy is similar to that in patients with diabetes mellitus. (See "General principles of insulin therapy in diabetes mellitus".)

Exocrine insufficiency may only become apparent when the patient begins to take a regular diet. Oral pancreatic enzyme replacement therapy is warranted. (See "Chronic pancreatitis: Management", section on 'Pancreatic enzyme replacement therapy'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Acute pancreatitis".)

SUMMARY AND RECOMMENDATIONS

●Pancreatic debridement is indicated for patients with pancreatic necrosis and progressive clinical sepsis as a complication of severe acute pancreatitis. Pancreatic and peripancreatic necrosis occurs when inflammation and vascular compromise result in the death of pancreatic parenchyma and peripancreatic fat. (See 'Introduction' above.)

●Infected pancreatic necrosis and symptomatic sterile necrosis are both accepted indications for debridement. The goal of pancreatic debridement is to excise all dead and devitalized pancreatic and peripancreatic tissue while preserving viable functioning pancreas, controlling resultant pancreatic fistulas, and limiting extraneous organ damage. For patients with biliary pancreatitis, cholecystectomy with intraoperative cholangiography is an important secondary objective of the surgery because this will prevent recurrent disease. (See 'Indications for pancreatic debridement' above.)

●The optimal timing for pancreatic debridement is three to four weeks following the onset of acute pancreatitis. Delayed debridement allows clinical stabilization of the patient, resolution of early organ failure, and a decrease in the intense inflammatory reaction in the retroperitoneum. (See 'Timing of debridement' above.)

●All patients with pancreatic necrosis undergoing debridement should have contrast-enhanced computed tomography (CT) scanning of the abdomen and pelvis to define the extent and location of necrotic areas as this will affect the surgical approach. (See 'CT scan' above.)

●In walled-off pancreatic necrosis, encapsulation of the process creates a localized mature collection analogous to a pancreatic pseudocyst. (See 'Walled-off pancreatic necrosis' above.)

●In suitable candidates, a "step-up" approach of percutaneous drainage and/or endoscopic drainage/debridement provides alternatives to surgery that can be equally effective. Percutaneous catheter drainage is primarily a bridging technique for patients who are too unstable to undergo surgical debridement, although one-third of patients can be managed with percutaneous drainage alone. Endoscopic debridement is performed via a transgastric or transduodenal approach and is limited to patients with walled-off pancreatic necrosis. (See 'Nonsurgical approaches to pancreatic debridement' above.)

●Preoperative discussion with patients and their caregivers should include the potential need for reoperations to drain intra-abdominal fluid collections, remove additional necrotic tissue, or control a pancreatic fistula. Patients with biliary pancreatitis should be informed that there is an increased risk of postoperative bile leak or biliary injury when a cholecystectomy is performed in the setting of retroperitoneal inflammation. If the CT scan shows involvement of the mesocolon, patients should be informed of the potential need for colon resection and a colostomy. (See 'Surgeon's safety checklist for pancreatic debridement' above.)

●Open surgical debridement is the gold standard for management of pancreatic necrosis. Laparoscopic debridement is primarily limited to patients with walled-off pancreatic necrosis. (See 'Surgical approaches to pancreatic debridement' above.)

●The reported mortality rate in patients undergoing debridement for pancreatic necrosis ranges from 4 to 25 percent. The mortality rate is related to the extent of necrosis, underlying organ failure, and infection of the necrotic tissue. Complications after pancreatic debridement include intra-abdominal fluid collections, bleeding, pancreatic fistulas, incisional hernias, and pancreatic insufficiency. (See 'Postoperative complications' above.)