43 Acute and Chronic Pancreatitis
Acute pancreatitis (AP) is defined as an acute inflammation of the pancreas with involvement of various adjacent tissues and organ systems, and may be due to gallstone, alcohol, and other causes. 1 Chronic pancreatitis (CP) is an irreversible inflammatory process characterized by the destruction of pancreatic parenchyma and ductal structures associated with fibrosis. 2 It is characterized by the presence of main pancreatic duct (MPD) strictures and/or stones and may lead to pain, exocrine, and endocrine pancreatic failure. Endoscopy plays an important role in the management of acute and chronic pancreatitis. Endoscopic ultrasound (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) are the two most common procedures performed in this setting. EUS is the cornerstone of diagnostic procedures, ranging from determining etiology of AP to confirming diagnosis of CP. ERCP should be considered as a therapeutic procedure only, and has been shown to be the basis of endoscopic therapy for CP, along with extracorporeal shock wave lithotripsy (ESWL). EUS-guided drainage of pancreatic collections has been applied extensively up to now for pseudocysts with mostly liquid contents, and recently developed endoscopic necrosectomy techniques have extended endoscopic management to walled-off necrosis containing solid debris. However, further studies are still required to standardize certain techniques and to investigate other alternatives. This chapter deals with diagnostic and therapeutic endoscopic procedures applied in patients with AP or CP explaining the technical modalities, and discussing indications and complications.
43.2 Diagnostic Approaches
EUS has largely surpassed ERCP with regard to diagnostic endoscopic procedures involving the pancreas, because of its relative limited invasiveness and low complication rates compared to ERCP (▶Table 43.1). 3 , 4 The most common applications include determination of AP etiology and diagnosis of CP.
43.2.2 Equipment and Techniques EUS
EUS combines endoscopic visualization with two-dimensional ultrasound and allows high-resolution imaging of the pancreatic parenchyma and ductal structures. Both linear and radial endoscopes may be used for diagnostic procedures, but image characteristics differ. However, solely a linear endoscope can be used for therapeutic procedures, including fine-needle aspiration (FNA) and drainage.
43.2.3 Guidelines and Systematic Reviews
EUS and Diagnosis of Acute Pancreatitis Etiology
EUS may help in determining etiology in patients with unexplained AP. In a prospective study of 201 patients with a single episode of unexplained AP, EUS identified a cause in 31%, including choledocholithiasis, biliary sludge, and CP. 5 Another prospective comparative study showed that the diagnostic yield of EUS was higher than that of magnetic resonance cholangiopancreatography (MRCP) in patients with unexplained AP (51 vs. 20%, p = 0.001). 6 Indeed, MRCP may fail to detect small stones (< 4 mm) or stones distally situated near the papilla of Vater. 7 Regarding patients with suspected biliary AP and choledocholithiasis and given the higher morbidity of ERCP compared to EUS, sequential EUS and ERCP were assessed in two series in an effort to better triage patients in need of treatment. EUS showed high accuracy (97–98%) for choledocholithiasis detection, similar or better to ERCP. 8 , 9 A systematic review of all seven studies assessing the EUS-based strategy showed that ERCP was avoided in 71.2% of cases. No complications were related to EUS, whereas sphincterotomy was associated with bleeding in up to 22% of patients undergoing ERCP. 10 Regarding cost-effectiveness, a Monte Carlo decision analysis reported that the EUS-first strategy was preferable for severe biliary AP, with reduced costs, fewer therapeutic ERCPs, and fewer complications. 11 Finally, pancreatic cancer should be excluded in patients above 40 years of age with unexplained AP. The American Society of Gastrointestinal Endoscopy (ASGE) guidelines suggest EUS for the evaluation of idiopathic AP for patients older than 40 years if history, physical examination, laboratory testing, and abdominal imaging with MRCP or computed tomography (CT) are unrevealing. 2
EUS and Diagnosis of Chronic Pancreatitis
EUS parenchymal and ductal features of CP are summarized in ▶Table 43.2. Each of these features was initially counted as 1 point (on a scale of 0–9) with higher scores increasing the probability of disease. Five or more features were consistent with CP, whereas absence of all features excluded CP. 12 However, uncertainty remained and a new consensus based on expert opinion assigned different weight to each feature to increase diagnostic accuracy 13 (▶Table 43.2). Nevertheless, this modified classification system failed to increase interobserver agreement for the diagnosis of CP compared to the initial scoring system. 14 This underscores the need to combine EUS findings with clinical, structural, and functional analyses and to be aware of the possible overdiagnosis of CP in case of recent AP, aging, male gender, tobacco or alcohol use, and obesity. 15
43.3 Therapeutic Approaches
43.3.1 Standard Techniques
ERCP allows therapeutic interventions of the pancreatic duct and it is the cornerstone of endoscopic therapy for pancreatic diseases. This procedure requires fluoroscopy and a fixed undercouch system to limit radiation exposure to the staff. 16 The team requires an endoscopist, an anesthesiologist, a radiology technician, and at least one nurse. The patient is in supine or prone position, for better anatomical view of the ducts. ERCP is performed with a side-viewing endoscope (duodenoscope) with a large operating channel (4.2 mm), which is introduced into the descending duodenum at a stable position en face to the papilla, as well as introduction of accessories in the bile or pancreatic duct. Necessary devices include a standard ball-tip catheter, a sphincterotome (short nose with a 20-mm wire), angulated hydrophilic-tip guidewires (0.025 and 0.035 in), balloon dilators (4–6 mm), bougies (7–10 F), Soehendra’s retrievers (8.5 and 10 F) for stricture dilation, a balloon stone extractor, a small Dormia basket, and plastic straight stents (from 3- to 12-cm length and 5 to 10 F). 17 Biliary or pancreatic duct cannulation is attempted, according to the indication of ERCP.
Pancreatic Sphincterotomy of the Major Papilla
Pancreatic duct cannulation is performed by placing the endoscope in front of the papilla and directing the ball-tip catheter or the sphincterotome, perpendicularly, toward the 1 o’clock direction. The guidewire technique or contrast injection may be used. Both techniques require extreme caution, especially in patients who do not have mild or moderate chronic pancreatitis, because of the high risk of post-ERCP pancreatitis, which is increased in case of multiple guidewire passes or high-volume injections. 18 Using the sphincterotome, a 5- to 10-mm incision is performed toward the 1 o’clock direction, with pure cutting current, to limit the possible future development of fibrosis and papillary stricture. 19 A pancreatic stent is usually inserted after pancreatic sphincterotomy to reduce the incidence of post-ERCP acute pancreatitis. 18
An alternative method to pancreatic sphincterotomy utilizes an endoscopic needle knife instead of a standard pull-type sphincterotome. In this case, the pancreatic stent is inserted beforehand. The tip of the needle knife is placed at the most proximal portion of pancreatic sphincter tissue that is overlying the stent. While using the stent as a guide to direct the cut along the plane of the pancreatic duct, the needle-knife tip is advanced over the top of the stent and down its longitudinal axis thereby “unroofing” the intraduodenal portion of the major papilla. 20
Pancreatic Sphincterotomy of the Minor Papilla
Sphincterotomy of the minor papilla might be indicated in case of pancreas divisum morphology, when pancreatic duct drainage is required. Similarly, to sphincterotomy of the major papilla, it can be performed with a standard or ultrataper pull-type sphincterotome, or with a needle-knife cut over a plastic stent. A retrospective comparative study demonstrated that overall complication as well as reintervention rates for papillary stricture were similar in those undergoing needle knife and pull-type sphincterotome minor papilla sphincterotomy. 21 The cutting wire of the sphincterotome or the needle knife is directed toward 11 o’ clock and pure cutting current is used. 20
Managing MPD Strictures
After access into the MPD and sphincterotomy, stent insertion may be performed in case of pancreatic strictures. This is achieved by first introducing the guidewire through the stricture, as far as possible, preferably with a loop at the proximal end. The second step consists of dilating, either by using a balloon, a boogie, or a Soehendra’s retriever for very tight, fibrotic strictures. 22 , 23 Polyethylene 8.5- to 10-F pancreatic stents tailored to the shape of the pancreatic duct and length of the stricture are most commonly used 23 (▶Fig. 43.1). Thinner stents (≤ 8.5 F) are related to more frequent hospitalizations for pain due to stent occlusion. 24
Extracorporeal Shock Wave Lithotripsy
ESWL allows fragmentation of radio-opaque pancreatic stones before ERCP, to facilitate their extraction. The technique of ESWL requires four components, namely a shock wave generator, a focusing system, a coupling mechanism, and a localizing unit, all of which are packed in the same apparatus. 25 Best results are obtained by the third-generation lithotripters, which are equipped with bidimensional fluoroscopic and ultrasonic targeting systems. The procedure should be performed on a slightly lateral decubitus position, under general anesthesia, with a maximum of 5,000 shocks per session delivered with increasing intensity at a rate of 90 shocks per minute. 26 Successful stone fragmentation following ESWL has been defined as stones broken into fragments less than or equal to 2 or 3 mm, or by the demonstration of a decreased stone density at X-ray, an increased stone surface, and heterogeneity of the stone, which may fill the MPD and adjacent side branches. 23 ERCP may follow during the same session (Video 43.1).
EUS-Guided Transmural Drainage
Pancreatic collection drainage is preferably performed under combined EUS and fluoroscopy guidance, unless the collection is bulging when only fluoroscopy may be used. Nevertheless, EUS-guided drainage has higher rates of technical success. 23 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 Therapeutic linear EUS endoscopes should be used. The procedure is performed with the patient under general anesthesia and endotracheal intubation, especially in case of large collections. Antibiotic prophylaxis is recommended for sterile pancreatic fluid collections Access can be gained through the stomach (cystogastrostomy), or the bulb (cystoduodenostomy). Puncture is performed by the electrosurgical needle of a 10-F cystenterostome. Then, a 0.035-in guidewire is inserted and the tract is enlarged by passing the cystenterostome into the collection, followed by the positioning of a double-pigtail stent and/or a nasocystic catheter. For the placement of multiple stents, further dilation of the transmural path is achieved by a balloon catheter. At least two double plastic pigtail stents should be inserted 29 (Video 43.2).
Endoscopic management of necrotic pancreatic collections (walled-off necrosis) containing solid debris requires a more aggressive approach. Necrosectomy includes a first step involving transmural drainage to gain access, followed by debridement of the necrotic cavity. After initial access is established, the tract is dilated up to 15 to 20 mm, followed by placement of multiple large-bore double-pigtail stents or of a single large-diameter fully covered metallic stent. 36 , 37 Debridement is achieved with a forward-viewing endoscope and various devices (nets snares, baskets), preferably with at least one double-pigtail stent or catheter left in place to maintain access. Debridement is combined with irrigation and repeated if necessary.
43.3.2 Guidelines and Systemic Reviews
Biliary Acute Pancreatitis
The role and timing of ERCP in biliary AP has been the subject of numerous trial, meta-analyses, and recommendations during the last 20 years. Concerning early ERCP, the latest study from the Cochrane Collaboration included seven randomized-controlled trials and concluded that in patients with biliary AP, there is no evidence that early routine ERCP significantly affects mortality and local or systemic complications, regardless of predicted severity. However, early ERCP with biliary sphincterotomy may be beneficial in patients with coexisting cholangitis or biliary obstruction. 38 Furthermore, a recent randomized-controlled trial showed that same-admission cholecystectomy reduced the rate of recurrent gallstone-related complications in patients with mild biliary AP, with a very low risk of cholecystectomy-related complications. This study underlines the indication of same-admission cholecystectomy in patients with mild AP instead of ERCP with biliary sphincterotomy, because ERCP with sphincterotomy may reduce the risk of recurrent biliary AP but will have no effect on other biliary events such as cholecystitis. 39 However, in patients with severe biliary AP and local complications requiring interval cholecystectomy, preoperative ERCP with biliary sphincterotomy may offer some protection against recurrent biliary-related complications 40 (▶Fig. 43.2).
Sphincter of Oddi Dysfunction
Pancreatic sphincter of Oddi (SOD) can be classified in three types: type 1 with pain, more than twofold elevated pancreatic enzymes on two occasions, and dilated MPD; type 2 with pain and either elevated enzymes or dilated MPD; and type 3 with only pain 41 . Types 1 and 2 patients may present with recurrent AP. Endoscopic approach varies according to centers; some advocate biliary and/or pancreatic sphincterotomy and others perform biliary sphincterotomy only, followed by pancreatic sphincterotomy if symptoms persist. A recent randomized trial of patients with recurrent AP demonstrated that patients with pancreatic SOD responded similarly to biliary sphincterotomy alone (51.5%) compared to combined biliary and pancreatic sphincterotomies (52.8%; p = 1) for the prevention of recurrent episodes of AP. 42 Furthermore, a multicenter, randomized, controlled trial failed to show any benefit of endoscopic therapy for SOD type 3 patients. 43