Prophylaxis of Post Endoscopic Retrograde Cholangiopancreatography Pancreatitis by an Endoscopic Pancreatic Spontaneous Dislodgement Stent

Transcription

1 CLINICAL GASTROENTEROLOGY AND HEPATOLOGY 2007;5: Prophylaxis of Post Endoscopic Retrograde Cholangiopancreatography Pancreatitis by an Endoscopic Pancreatic Spontaneous Dislodgement Stent ATSUSHI SOFUNI,* HIROYUKI MAGUCHI, TAKAO ITOI,* AKIO KATANUMA, HIROYUKI HISAI, TEITETSU NIIDO, MASAYUKI TOYOTA, TSUNESHI FUJII, # YOUJI HARADA, and TADANORI TAKADA *Department of Gastroenterology and Hepatology, Tokyo Medical University Hospital, Tokyo; Center for Gastroenterology, Teine-Keijinkai Hospital, Sapporo; Department of Gastroenterology, Japan Red Cross Date General Hospital, Date; Department of Gastroenterology, Toda Chuo General Hospital, Toda; Department of Surgery, Teikyo University Hospital, Tokyo; and # Department of Gastroenterology, Asahikawa City Hospital, Asahikawa, Japan Background & Aims: Pancreatitis after endoscopic retrograde cholangiopancreatography (ERCP) is the most common and potentially serious complication of ERCP. The frequency of post-ercp pancreatitis generally is reported to be between 1% and 9%. One cause of pancreatitis is retention of pancreatic juice resulting from papilledema after the procedure. We conducted a randomized controlled multicenter study to evaluate whether placement of a temporary pancreatic stent designed for spontaneous dislodgement prevents post-ercp pancreatitis. Methods: The subjects were 201 consecutive patients who underwent ERCP. The patients were randomized into the stent placement group (S group 98) or the nonstent placement group (ns group 103). The stent used was 5F in diameter, 3 cm in length, straight, and unflanged inside. Results: Stents were placed successfully in 96% of the S group, and spontaneous stent dislodgment was recognized in 95.7% of those. The mean duration to dislodgment was 2 days, and there were no severe complications. The overall frequency of post-ercp pancreatitis was 8.5%. The frequency of post- ERCP pancreatitis in the S and ns groups was 3.2% and 13.6%, respectively, showing a significantly lower frequency in the S group (P.019). The mean increase in amylase level in the pancreatitis patients was significantly higher in the ns group (P.014). Conclusions: The randomized controlled multicenter trial showed that placement of a pancreatic spontaneous dislodgment stent significantly reduces post-ercp pancreatitis. Postendoscopic retrograde cholangiopancreatography (ERCP) pancreatitis, the most common and potentially serious complication of ERCP, is reported to occur in 1% 40% of cases in recent large prospective studies Some investigators have reported several factors that increase the risk of post-ercp pancreatitis Although numerous mechanisms of post-ercp pancreatitis have been suggested, 1 25 one of the most likely mechanisms is impaired drainage from the pancreatic duct caused by papillary edema and/or spasm of the sphincter of Oddi after the procedure ,19,22,25 As a countermeasure, some endoscopists have inserted a nasopancreatic drainage tube into the pancreatic duct 9,10 or used a flanged pancreatic stent, not considering the possible advantages of spontaneous dislodgement ,19,20 A pancreatic spontaneous dislodgement stent (PSDS) recently has become available commercially and has been reported to be effective in preventing post-ercp pancreatitis. 1,15,17 20,25 Pancreatic duct stents (PS) are classified into those with and without flanges on the pancreatic ductal side. The former is unlikely to dislodge naturally, and endoscopic removal often is necessary. As for the latter unflanged PS, the rate of natural dislodgement within a short period is high, 1,17,25 and re-insertion of an endoscope for removal generally is unnecessary. We first conducted a preliminary single-center, randomized, controlled study to prospectively evaluate the efficacy of a temporary unflanged PS in preventing post-ercp pancreatitis. 15 Based on the encouraging results from our preliminary study, we conducted a randomized, controlled, multicenter study to evaluate whether placement of a PSDS prevents pancreatitis after ERCP-related procedures. Materials and Methods Materials This randomized, controlled, multicenter trial was executed between June and November 2005 at 6 large endoscopic units performing more than 400 ERCPs each per year. We planned to include 220 patients to allow for patients being excluded. The sample size calculations indicated that approximately 150 patients would be required in each study group to detect a decrease in the incidence of post-ercp pancreatitis from 15% to 5% (.05,.2; 2-tailed test) A total of 201 consecutive patients underwent ERCP-related procedures. The patients were randomized into a stent placement group (S group 98 patients), or a nonstent placement group (ns group 103 patients) using the envelope method (Figure 1). The study group included patients who possessed risk factors of post-ercp pancreatitis, but the following patients were planned to be excluded as follows: (1) patients who could not provide written informed consent, (2) patients deemed inappropriate for this trial (although there actually were none in the present study), (3) patients with a performance status of 4 (eg, Abbreviations used in this paper: ERCP, endoscopic retrograde cholangiopancreatography; ns group, nonstent placement group; PS, pancreatic duct stent; PSDS, pancreatic spontaneous dislodgement stent; S group, stent placement group by the AGA Institute /07/$32.00 doi: /j.cgh

2 1340 SOFUNI ET AL CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 5, No. 11 Figure 1. Trial profile. completely disabled, cannot carry out any self-care, totally confined to bed or chair), (4) patients in whom the duodenal papilla could not be accessed endoscopically, (5) patients requiring pancreatic duct drainage, (6) patients requiring endoscopic papillectomy, (7) patients with pancreatic head cancer, (8) patients with pancreas divisum case, and (9) patients in whom the ERCP procedure was not completed within 1 hour from the transoral insertion of the scope. Study Design Before endoscopy, the patient s past history was taken and a physical examination was performed. Pharyngeal anesthesia was induced with a topical anesthetic and conscious sedation by intravenous medication. We gave 100 mg of gabexate mesylate dissolved in 500 ml solution, administered by continuous intravenous infusion for 12 hours beginning immediately after ERCP procedures, according to the guidelines for initial treatment based on the acute pancreatitis guide to medical care by the Ministry of Health, Labour and Welfare Intractable Pancreatic Disease Research Group in Japan. An antibiotic also was administered by drip infusion at the same time. Except for the gabexate mesylate the administered medication was at the discretion of the endoscopist. Before cannulation, indigo carmine pigment was sprayed on the accessory papilla before ERCP-related procedures to evaluate the accessory papilla patency within 30 seconds (patent or not patent/unclear). The kind of ERCP devices used (ie, catheter, sphincterotome, and guidewire) were not limited to a specific type. About the kind of guidewire used for stent placement, we used mostly Radifocus (Terumo Co., Ltd., Tokyo, Japan) or Jagwire (Boston Scientific Japan, Tokyo, Japan). In this study, contrast agent was injected first in the ERCP procedures, as is the custom in Japan. Sphincterotomy was performed with a standard traction sphincterotome and blended electrosurgical cutting and coagulation current. We used a 5F straight polyethylene stent, 3 cm in length, unflanged on the pancreatic ductal side, and with 2 flanges on the duodenal side (GPDS-5-3; Cook Endoscopy, Inc., Winston-Salem, NC) (Figure 2), and the stent dislodgment was confirmed by daily abdominal radiographs taken every morning until confirmation of dislodgement. In the current study, the stent was planned to be removed duodenoscopically on the morning of the fourth day if it had not been dislodged by the third day. The randomization of patients was performed when the papilla was visualized via the endoscope. The group randomized to stent placement, like the ns group, first underwent ERCP and related procedures (biliary or pancreatic procedures). After those procedures, pancreatic duct cannulation, contrast injection, and guidewire insertion were performed subsequently for stent placement. The stent was passed over a guidewire under fluoroscopic guidance. In the ns group, the procedure was finished without placement of a stent. When the patient was randomized to the ns group, the procedure was finished without cannulation and injection of the pancreatic duct after the biliary procedures if it was a routine biliary case with no pancreatic duct injection. At the end of the procedures, the endoscopists recorded the results and details of the investigation items. After ERCP, patients fasted until blood tests confirmed there was no pancreatitis or other complications on the following day. All patients were hospitalized for the ERCP procedure and observation. All patients provided written informed consent before entry into the study. Institutional review boards at each institution reviewed and approved the study. Figure 2. Pancreatic stent. The stent used was a polyethylene 5F diameter, 3-cm long, straight, unflanged on the pancreatic ductal side, with 2 flanges on the duodenal side (GPDS-5-3; Cook Endoscopy, Inc.).

3 November 2007 PROPHYLAXIS OF POST ERCP BY PSDS 1341 Table 1. Characteristics of 201 Patients Definitions S group (%) ns group (%) No. of patients Unsuccessful case of stent 4 placement Mean age, y (range) 67 (24 88) 66 (26 92) (28) 29 (28) (72) 74 (72) Sex: Male/female 60/38 64/38 History of pancreatitis 8 (9) 9 (8) History of ERC-related 15 (15) 18 (17) procedures Normal bilirubin level 22 (22) 26 (25) Examination a : ERCP alone 27 (4/11) (29) 19 (4/8) (18) (ERC alone/erp alone) ES 15 (15) 13 (13) ES ENBD 3 (3) 3 (3) ES EBD 4 (4) 3 (3) non-es ENBD 20 (20) 13 (13) non-es EBD 6 (6) 5 (5) IDUS (bile duct/pancreatic 26 (22/6/2) (27) 26 (20/8/0) (26) duct/bile and pancreatic duct) a Biopsy (bile duct/pancreatic 10 (5/5/0) (10) 19 (9/10/0) (19) duct) and/or PPJ EPBD 10 (10) 11 (11) Sphincter of Oddi 1 (1) 0 (0) manometry POCS 0 (0) 2 (2) Pancreatic duct stricture 4 (2/2/0) (4) 8 (5/3/0) (8) (head/body/tall) Accessory papilla patency 32/66 35/68 (patent/not patent or not clear) Duodenal diverticulum 22 (22) 23 (23) Acinarization 1 (1) 0 (0) Intramural contrast injection 5 (5) 2 (2) Initial pancreatography 58 (59) 58 (56) Difficulty of cannulation (A/B/ 4/5/16/72 3/0/5/95 C/D) b Grade of ERCP skill (excellent/ 44/7/9/38 42/10/14/37 very good, good/adequate) b Mean procedure time mind 26.7 (1 64) 24.6 (1 76) (range) Procedure time 30 min min ERC, endoscopic retrograde cholangiography; ERP, endoscopic retrograde cholangiopancreatography; ES, endoscopic sphincterotomy; ENBD, endoscopic nasobiliary draignage; EBD, endoscopic biliary draignage; IDUS, intraductal ultrasonography; PPJ, aspiration of pure pancreatic juice; EPBD, endoscopic papillary balloon dilation; POCS, peroral cholangioscopy. a All examinations overlapped. b For criteria, see Outcomes section of text for detail. The definition of post-ercp pancreatitis was standardized by a consensus conference held in 1991 and the proposed criteria have become widely accepted. 1,22 Post-ERCP pancreatitis was defined as pancreatic pain and hyperamylasemia within 24 hours of the procedure. Pancreatic pain was defined as persistent pain in the epigastric or periumbilical region. Hyperamylasemia was defined as an increase in the serum amylase level to greater than 3 times the upper normal limit in each institution. The definition of severity was modified based on the criteria of Cotton et al. 22 Although the Cotton criteria defined the degree of severity as days of hospitalization, 2 11 we used the same number of days until eating a meal. Outcomes The primary study end points were the frequency and severity of post-ercp pancreatitis. We also evaluated hyperamylasemia, the success rate of stent placement, the duration of stent dislodgment, and complications in both groups. Then we also evaluated several risk factors as shown in Table 1. The grade of difficulty of cannulation was classified as follows: A, impossible or unsuccessful cannulation; B, cannulation difficult but possible; C, successful cannulation achieved by an experienced endoscopist; and D, easy. The degree of skill of the initial endoscopist was classified by the number of years of experience: A (excellent), more than 10 years; B (very good), less than 10 but more than 6 years; C (good), 3 6 years; and D (adequate), less than 3 years. Each endoscopist has performed Table 2. Final Diagnosis in Both Groups S group ns group Biliary diseases CBD stone Cholangitis 19 7 Mirizzi syndrome 1 1 Cholecystitis GB stone GB polyp 1 6 GB adenomyomatosis 4 3 GB carcinoma 2 1 Cholanglocarcinoma 5 6 Cholangiocellular carcinoma 3 1 Benign biliary stricture 2 5 CBD dilatation 2 1 Primary sclerosing cholangitis 0 1 Pancreatic diseases IPMN 8 10 MCN 0 1 SCN 0 1 Chronic pancreatitis 3 6 Acute pancreatitis 1 2 Pancreatic cyst 1 3 Pancreatic carcinoma 0 6 Other conditions SOD 2 0 PBM 0 1 Papilla of vater tumor 1 1 Malignant lymphoma 1 0 Liver dysfunction 1 1 Hepatocellular carcinoma 0 2 Intrahepatic stone 1 2 Cholangioduodenal fistula 1 0 Normal 1 0 NOTE. There was overlap of diagnoses in some patients. CBD, common bile duct; GB, gallbladder; IPMN, intraductal papillary mucinous neoplasm; MCN, mucinous cystic neoplasm; SCN, serous cystic neoplasm; SOD, sphincter of Oddi dysfunction; PBM, pancreatobiliary maljunction.

4 1342 SOFUNI ET AL CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 5, No. 11 Table 3. Summary of Stent Placement No. of patients 98 Success rate in stent placement a 94 (96.0%) Rate of spontaneous stent dislodgement 90 (95.7%) Rate of endoscopic removal 4 (4.3%) Duration time to dislodgement, days (range) 2.0 (1 4) Complications (n 94) Stent migration 0 (0%) Post-ERCP pancreatitis 3 (3.2%) Hyperamylasemia 31 (33%) Hemorrhage 0 (0%) Perforation 0 (0%) Infection (cholangitis, cholecystitis) 0 (0%) Others 0 (0%) Mean serum amylase level after procedures, ( ) U/L (range) a Complications in 4 unsucessful stent placement cases: 2 hyperamylasemias. more than 200 ERCP procedures per year for 2 20 years. It was recorded if the endoscopist changed during the session. Statistical Analysis The 2 test (with Yates correction) or the Fisher exact test was used to determine the significance of associations. A P value of less than.05 indicated a statistically significant difference. Univariate evaluation was first made for each potential risk factor using the 2 test. In the second step, only the significant factors (P.05) in the 2 analysis were included in the multivariate (logistic regression) analysis. Results Table 2 shows the final diagnosis on the basis of which the indications for ERCP were selected in both groups. Table 2 shows the characteristics in both groups. The mean age was 66.5 years (range, y), and the male:female ratio was 124:77. All 201 patients received ERCP and/or ERCP-related procedures in which endoscopy was performed to cannulate the bile duct, pancreatic duct, or both. Pancreatography (alone and in addition to cholangiography) was performed in 73.6% (148 of 201) and cholangiography (alone and in addition to pancreatography) also was performed in 90.5% (182 of 201). There were few ansa pancreaticus or anatomic deformity cases in this study. Moreover, we planned to exclude pancreas divisum cases from the study at the moment it was diagnosed as pancreas divisum after ERCP. In actual fact, no such case was seen in this study. No cannulation of the minor papilla was intended or performed in this group. Pancreatic Stent Placement The success rate of PS placement was 96.0% (94 of 98). The rate of spontaneous dislodgment by day 3 was 95.7% (90 of 94) and the stent had to be removed endoscopically in 4 cases (4.3%). The mean duration to dislodgment was 2 days (Table 3). No major complications caused by stent placement were seen. One patient had continuing hyperamylasemia for 4 days because the papilla of Vater opened with a diverticulum and the tip of the stent was trapped by the diverticulum. Complications in 4 unsuccessful cases consisted of hyperamylasemia in 2 cases. Pancreatitis was not seen in the cases of unsuccessful stent placement. Post Endoscopic Retrograde Cholangiopancreatography Pancreatitis The overall frequency of post-ercp pancreatitis was 8.5% (17 of 201). The frequency of post-ercp pancreatitis in the S and ns groups was 3.2% (3 of 94) and 13.6% (14 of 103), respectively, showing a significantly lower frequency of post- ERCP pancreatitis in the S group (P.019). Furthermore, the mean increase in amylase level in the pancreatitis patients was significantly higher in the ns group (1072 vs 2210 IU/L, P.014). Table 4 shows the frequency and severity of post-ercp pancreatitis in the S and ns groups. The severity in the S group was mild, moderate, and serious in 2, 1, and 0 patients, compared with 8, 4, and 0 patients in the ns group. There was no statistically significant difference in frequency of severe pancreatitis between the S and ns groups because of the limited number of patients. The frequency of hyperamylasemia cases was similar in both groups, but the mean serum amylase of hyperamylasemia was significantly higher in the ns group (767 vs 1364 IU/L, P.019). The frequency of abdominal pain was significantly higher in the ns group (5 vs 19 patients, P.005). Table 4. The Details of Post-ERCP Pancreatitis S group ns group P value No. of patients Post-ERCP pancreatitis (%) a 3 (3.2) 14 (13.6).05 (.019) Severity of post-ercp pancreatitis Mild 2 8 NS (.139) Moderate 1 6 NS (.156) Severe 0 0 NA Mean serum amylase level after procedures in pancreatitis cases (range) 1072 ( ) 2210 ( ).05 (.014) Hyperamylasemia 31 (33%) 34 (33%) NS (.996) Mean serum amylase level, IU/L (range) 767 ( ) 1364 ( ).05 (.019) Abdominal pain 5 (5.3%) 19 (18%).05 (.005) Overall mean serum amylase level after procedures (range) 373 ( ) 529 (8 4884) NS (.131) NOTE. The chi-square test (with Yates correction) or Fisher s exact test was used to determine the significance of associations. A P value of less than.05 was considered to indicate a stastically significant difference. NA, not available; NS, not significant. a The overall rate of post-ercp pancreatitis: 8.5%.

5 November 2007 PROPHYLAXIS OF POST ERCP BY PSDS 1343 Table 5. The Rate of Post-ERCP Pancreatitis in Diseases S group pancreatitis ns group pancreatitis patients (%) patients (%) Biliary diseases CBD stone 36 1 (3) 40 4 (10) Cholangitis (14) Mirlzzi syndrome 1 1 Cholecystitis (20) GB stone (9) GB polyp 1 6 GB adenomyomatosis 4 3 GB carcinoma 2 1 Cholangiocarcinoma (33) Cholangiocellular carcinoma 3 1 Benign biliary stricture (40) CBD dilatation 2 1 Primary screlosing 0 1 cholangitis Pancreatic diseases IPMN (10) MCN 0 1 SCN 0 1 Chronic pancreatitis 3 1 (33) 5 1 (20) Acute pancreatitis 1 2 Pancreatic cyst (33) Pancreatic carcinoma (14) Other diseases SOD 2 1 (50) 0 PBM 0 1 Papills of Vater tumor 1 1 Malignant lymphoma 1 0 Liver dysfunction 1 1 Hepatocellular carcinoma (50) Intrahepatic stone 1 2 Cholangioduodenal fistula 1 0 Normal 1 0 NOTE. Factors with a high frequency ( 20%) association with post- ERCP pancreatitis are underlined. CBD, common bile duct; GB, gallbladder; IPMN, intraductal papillary mucinous neoplasm; MCN, mucinous cystic neoplasm; SCN, serous cystic neoplasm; SOD, sphincter of Oddi dysfunction; PBM, pancreaticobiliary maljunction. Risk Factors of Post Endoscopic Retrograde Cholangiopancreatography Pancreatitis Table 5 shows the incidence rate of post-ercp pancreatitis in both groups. Table 6 shows various factors, including those with a high frequency of post-ercp pancreatitis, and the results of univariate analysis of patient-related and procedurerelated risk factors in both groups. Although pancreatitis caused by the high-frequency factors was reduced by PS placement, the difference was not statistically significant. Pancreatitis was related significantly only to tissue sampling by any method, and initial pancreatography in univariate analysis. Discussion This randomized controlled trial showed that placement of a PSDS was feasible, significantly reduced the rate of post-ercp pancreatitis, and prevented progression to severe pancreatitis. Furthermore, PSDS placement caused significant reduction of serum amylase levels and abdominal pain after ERCP-related procedures. In most cases, post-ercp pancreatitis generally is mild and requires only conservative treatment. However, substantial complications sometimes occur, and on occasion they are fatal. The various mechanisms of post-ercp pancreatitis include postprocedural impaired drainage of the pancreatic duct caused by papillary edema, or spasm of the sphincter of Oddi, or both ,15,22,25 Another complication is local injury of the papilla and pancreatic duct as a result of the procedure or forceful and repetitive contrast injections causing local inflammation. 1 20,26 This may lead to premature intracellular activation of proteolytic enzymes, consequently causing further damage and local inflammation as indicated by increased levels of cytokines, and possible initiation of a systemic inflammatory response with multiorgan involvement. 1,10,11,13 To date, several attempts to prevent post-ercp pancreatitis (ie, placement of a PS with internal and external flanges, or a nasopancreatic drainage tube 9,10 ) have been made. Chemoprophylaxis to reduce synthesis and secretion of proteolytic enzymes (octreotide or somatostatin) or administration of an antiproteolytic drug (gabexate mesylate) also has been attempted The effects varied and there is no consensus on whether chemoprophylaxis is useful for preventing post-ercp pancreatitis. We used gabexate mesylate in both groups in this study. Several, mainly nonprospective, randomized studies 9 12,14,18 21 have evaluated endoscopic drainage using a PS with flanges on both sides, unlike our PSDS, for preventing post-ercp pancreatitis in high-risk patients. The results suggested that the frequency of post-ercp pancreatitis decreased, and the PS provided a maintained drainage route when the papilla was blocked as a result of edema, or spasm of sphincter of Oddi, or both, after the procedure. Recently, Freeman 17 concluded that the insertion of a PS for high-risk cases reduced the frequency of post- ERCP pancreatitis by 4% 23%. In contrast, Smithline et al 12 reported that PS insertion did not confer a significant beneficial effect in patients with previous biliary sphincterotomy. All previous studies reported that the study essentially consisted of patients at high risk for post-ercp pancreatitis, and most were retrospective studies. The selection of risk factors and determination of the patients possessing those may contain per se bias. ERCP procedures also involve comparatively wideranging variables (ie, the experience of the endoscopists, difficulty of cannulation, and so forth). Therefore, in the present study, we performed placement of a PSDS in consecutive ERCP patients regardless of risk factor, based on the results of our preliminary single-center, randomized, controlled trial. 15 In that study, we evaluated prophylaxis of post-ercp pancreatitis using the same unflanged 5F PSDS in 80 consecutive patients, including those who underwent simple ERCP and those who received additional manipulation of the papilla through several stressful examinations including manometry, intraductal ultrasonography, and aspiration of pure pancreatic juice. The trial revealed that a temporary unflanged 5F PS reduced the frequency of post-ercp pancreatitis. We designed the present randomized, controlled, multicenter trial based on that study. The results of the present study showed that the insertion of a PSDS significantly reduced the frequency of post-ercp pancreatitis (3.2% vs 13.6%), and mean serum amylase levels after the procedures (1072 vs 2210 IU/L). In particular, in case of

6 1344 SOFUNI ET AL CLINICAL GASTROENTEROLOGY AND HEPATOLOGY Vol. 5, No. 11 Table 6. The Rate of Post-ERCP Pancreatitis and Analysis of Various Risk Factors Post-ERCP pancreatitis S group (%) ns group (%) Univariate P value Mean age, y (range) 60 1/27 (3.7) 6/29 (20.7) /71 (2.8) 8/74 (10.8).557 Sex Male 1/60 (1.7) 8/64 (12.5).661 Female 2/38 (5.2) 6/39 (15.4).649 History of pancreatitis 2/8 (25) 0/8 (0).947 History of ERCP-related procedures 1/15 (6.7) 1/18 (5.6).877 Normal bilirubin level 2/71 (2.8) 7/77 (9.1).375 Examination ERCP alone 1/27 (3.7) 7/19 (36.8).078 ERC alone 0/4 (0) 0/4 (10.6).831 ERP alone 0/11 (0) 2/8 (25).884 ES 0/15 (0) 1/13 (7.7).582 ES ENBD 1/3 (33.3) 1/3 (33.3).182 ES EBD 0/4 (3) 1/3 (33.3).873 non-es ENBD 1/20 (5.0) 2/13 (15.4).805 non-es EBD 0/6 (0) 1/5 (20).618 IDUS (total) 1/26 (3.8) 5/26 (19.2).519 IDUS (bile duct) 0/22 (0) 4/20 (20).909 IDUS (pancreatic duct) 1/6 (16.7) 1/6 (16.7).672 IDUS (bile and pancreatic duct) 0/2 (0) 0 (0).403 Tissue sampling by any method (biopsy/brush/ppj) (total) 1/10 (10) 5/19 (26.3).045 a Bile duct sampling 0/5 (0) 4/9 (44.4).052 Pancreatic duct sampling 1/5 (20.0) 1/10 (10).884 Bile and pancreatic duct sampling 0 (0) 0 (0) - EPBD 0/10 (0) 2/11 (18.2).788 Sphincter of Oddi manometry 0/1 (0) 0 (0).138 POCS 0 (0) 0/2 (0).403 Pancreatic duct stricture None 1/90 (1) 12/95 (12.6).561 Head 0/2 (0) 2/6 (33.3).345 Body 1/2 (50) 0/2 (0).802 Tail 0 (0) 0 (0) - Accessory papilla patency Patent 3/32 (9) 4/35 (11.4).655 Not patent or not clear 0/66 (0) 10/68 (14.7).703 Duodenal diverticulum 0/22 (0) 2/23 (8.7).526 Acinarization 0/1 (0) 0 (0).759 Intramural contrast injection 1/5 (20) 0/2 (0).704 Initial pancreatography 3/58 (5.2) 19/58 (32.8).007 a Difficulty of cannulation A 0/4 (0) 0/3 (0).908 B 0/6 (0) 0 (0).997 C 0/16 (0) 1/5 (20).845 D 3/72 (4.2) 13/95 (13.7).753 Grade of ERCP skill Excellent 1/44 (2.3) 7/42 (16.7).854 Very good 1/7 (14.3) 1/10 (10).993 Good 0/9 (0) 3/14 (21.4).754 Adequate 1/38 (2.6) 3/37 (8.1).512 Procedure time, min 30 1/54 (1.9) 8/67 (11.9) /44 (4.5) 5/36 (13.9).974 NOTE. Factors with a high frequency ( 20%) association with post-ercp pancreatitis are underlined. ERC, endoscopic retrograde cholangiography; ERP, endoscopic retrograde cholangiopancreatography; ES, endoscopic sphincterotomy; ENBD, endoscopic nasobiliary drainage; EBD, endoscopic biliary drainage; IDUS, intraductal ultrasonography; PPJ, aspiration of pure pancreatic juice; EPBD, endoscopic papillary balloon dilation; POCS, peroral cholangioscopy. a P.05.

7 November 2007 PROPHYLAXIS OF POST ERCP BY PSDS 1345 hyperamylasemia, placement of a PSDS significantly reduced the mean serum amylase level (767 vs 1364 IU/L). The rate (13.6%) of pancreatitis in the ns group was high compared with that of the S group. The overall rate of post-ercp pancreatitis was 8.5% in all patients, including those at risk. This agrees in general with previous reports (1% 9%). 1 8,14 16 Moreover, it was reported that the rate of post-ercp pancreatitis in patients with risk factors ranges from 1% to as high as 40%. Akashi et al 30 clarified that abdominal pain is the most important feature of post-ercp pancreatitis. It is often difficult to distinguish mild episodes of acute pancreatitis from abdominal discomfort associated with hyperamylasemia (seen in up to 70% of patients after ERCP, including many who are asymptomatic). The PSDS insertion significantly reduced the appearance of abdominal pain (5 vs 19 cases). Although we fortunately did not have any cases of severe pancreatitis, we speculate that PSDS insertion may have prevented severe post-ercp pancreatitis. The rate of stent placement failure was 4.0% (4 cases). The cause of all failures was inability to cannulate the pancreatic duct. Of these, one was after endoscopic papillary balloon dilation, another was after endoscopic sphincterotomy. In these 4 unsuccessful cases, the only complication was hyperamylasemia, seen in 2 cases. It is difficult to cannulate the pancreatic duct after those procedures, and the procedure of cannulation itself for insertion of PS after endoscopic papillary balloon dilation and endoscopic sphincterotomy may cause pancreatitis. Freeman et al 1,20 also reported that unsuccessful cases were at higher risk of pancreatitis. We should therefore consider adapting the method of insertion of the PS for patients with such risk factors and for those in whom cannulation is difficult, for example, using the method that involves only insertion of a guidewire before the main procedure. Moreover, it occasionally is difficult to place a stent in ansa pancreaticus or anatomic deformity cases. There were few ansa pancreaticus or anatomic deformity cases in this study and if we came across such a case we carefully used the Radifocus guidewire and generally were able to place a stent. Freeman et al 1,2 reported that the high risks of post-ercp pancreatitis were both patient-related risk factors (ie, young age, female sex, suspected sphincter of Oddi dysfunction, and so on), and procedure-related risk factors (ie, pancreatic duct injection, difficult or impossible cannulation, and precut (access) sphincterotomy, and so on). Table 6 showed the rate of post-ercp pancreatitis of patient-related and procedure-related risk factors in both groups. On univariate analysis, post-ercp pancreatitis was related significantly only to tissue sampling by any method and initial pancreatography. However, our data lacked power to discuss them or to perform a multivariate analysis of risk factors because there were few cases of post- ERCP pancreatitis. The purpose of our study was to evaluate whether a PSDS is effective for prevention of post-ercp pancreatitis, thus this study was performed in all patients needing ERCP and related procedures, except for those meeting the exclusion criteria. The number of patients at high risk was not enough to fully evaluate the predictive value of risk factors of post-ercp pancreatitis. A study of patients in the previously described highrisk groups needs to be conducted in a large-scale, multicenter, randomized trial, based on the findings of the present study. The stent designed for this trial, resulting from our experience in a preliminary study, was 5F in diameter, 3 cm in length, with a straight unflanged internal surface. Stents with various diameters (3F 7F), lengths ( cm), and with or without flanges have been used in previous studies of post-ercp pancreatitis. However, it has not been clarified what kind of stent is best. The present study showed that the presence or absence of internal flanges is an important point. An internal flange is likely to make spontaneous PS dislodgment difficult, and, in such cases, generally the PS has to be removed 7 14 days after placement by additional endoscopy, which not only may injure the pancreatic duct, but also may be an economic burden. An unflanged stent designed to pass spontaneously from the pancreatic duct may obviate the need for a second endoscopic procedure for stent retrieval. It also may reduce the overall cost of treatment and procedures, and the pancreatic duct is less likely to be injured by an internal flange when the PS dislodges spontaneously. It has been reported that 86% of 3F stents dislodged spontaneously. 25 The results of our preliminary study suggested that the unflanged duodenal pigtail-type stent dislodges spontaneously at a higher rate. 15 The spontaneous dislodgement rate was 95.7%, and the duration until dislodgement was 2.7 days on average. In the present study, we used an unflanged PS, planning to remove the PS endoscopically if it did not dislodge within 3 days. PS retention for prolonged periods of time is a significant risk factor with respect to chronic pancreatitis. 1,25,31 33 Rashdan et al 25 reported that 3F 4F stents are more effective than traditionally used stents for prevention of post-ercp pancreatitis, and that 5F 6F stents cause more significant stent-induced pancreatic duct changes than 3F 4F stents. However, 3F 4F stents require a small-caliber guidewire ( inch), and the procedure using a small-caliber guidewire is difficult and requires a high level of experience. 1,25,31,32 Furthermore, the 3F 4F stent is not available in Japan. In contrast, the inch guidewire used for the 5F PS is relatively easy to use for stent placement. In this study, therefore, we selected a 5F PS. We also considered that the straight type of PS shape on the duodenal side is an important feature facilitating placement of the stent. Both types may dislodge spontaneously into the duodenum as a result of pancreatic juice flow or friction with passing food. Although the unflanged pigtail-type may be dislodged spontaneously at a higher rate as a result of friction with passing foods and duodenal peristalsis, handling of the short duodenal pigtail stent is slightly complicated, such as sudden forward movement of the stent on release, and it requires close attention and experience. That is why we selected the straight PS with a flange on the duodenal side. In conclusion, this study clearly shows that this PSDS placement approach will have a great impact on the prevention of post-ercp pancreatitis, although the risk factors of post-ercp pancreatitis are thought to be multifactorial. A large-scale, multicenter trial is needed to clearly identify the risk factors and to decide which types of patients require insertion of a PSDS for prevention of post-ercp pancreatitis. Appendix The Japanese Pancreatic Stent-Hokkaido Kanto Study Group consists of Atsushi Sofuni, MD, and Takao Itoi, MD (Department of Gastroenterology and Hepatology, Tokyo Medical University Hospital); Hiroyuki Maguchi, MD, and Akio Katanuma, MD (Center for Gastroenterology, Teine-Keijinkai Hospital); Hiroyuki Hisai, MD (Department of Gastroenterology, Japan Red Cross Date General Hospital); Teitetsu Niido,

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Effect of a novel pancreatic stent design on short-term pancreatic injury in a canine model. Endoscopy 2006;38: Address requests for reprints to: Atsushi Sofuni, MD, PhD, Department of Gastroenterology and Hepatology, Tokyo Medical University, Nishishinjuku, Shinjyuku-ku, Tokyo, Japan. a-sofuni@amy.hi-ho.ne.jp; fax: (81) The authors are indebted to Professor J. Patrick Barron of the International Medical Communications Center of Tokyo Medical University for his review of this manuscript. The authors thank Cook Endoscopy for their support of this trial, Professor Toshio Morizane, MD, and Kanagawa Dental College, for support in statistical analysis of this study.